IONM in Spinal Surgery - Revision history

Wdoyon: /* Others */

2022-01-28T01:51:47Z

Others

← Older revision		Revision as of 20:51, 27 January 2022
Line 59:		Line 59:
	==Others==		==Others==

	'''1. Interbody cages and bone grafts.''' For spinal decompressions involving a discectomy, the surgeon will remove a part or all of the intervertebral disc. If so, it is necessary to fill the empty disc space between the vertebral ~~body~~ with either a bone graft (e.g., autograft, allograft) or an interbody cage to ~~restore~~ the height of the spine. These devices are cylindrical or square-shaped and often threaded for increased stability. The interbody cage or bone graft is inserted by distracting the space between the discs. Some interbody cages are expandable, which allows for a more optimal fit.		'''1. Interbody cages and bone grafts.''' For spinal decompressions involving a discectomy, the surgeon will remove a part or all of the intervertebral disc. If so, it is necessary to fill the empty disc space between the two vertebral bodies with either a bone graft (e.g., autograft, allograft) or an interbody cage to maintain the height of the spine. These devices are cylindrical or square-shaped and often threaded for increased stability. The interbody cage or bone graft is inserted by distracting the space between the discs. Some interbody cages are expandable, which allows for a more optimal fit.

	'''2. Ondontoid (dens) fracture'''		'''2. Ondontoid (dens) fracture'''

Wdoyon: /* Others */

2022-01-28T00:18:34Z

Others

← Older revision		Revision as of 19:18, 27 January 2022
Line 59:		Line 59:
	==Others==		==Others==

	'''1. Interbody cages and bone grafts.''' For ~~different reasons~~, ~~spinal surgeries may require~~ the ~~removal of~~ part or all of the intervertebral disc. If so, it is necessary to fill the empty disc space with either a bone graft (e.g., autograft, allograft) or an interbody cage to restore the height of the spine. These devices are cylindrical or square-shaped and often threaded for increased stability. The interbody cage or bone graft is inserted by distracting the space between the discs. Some interbody cages are expandable, which allows for a more optimal fit.		'''1. Interbody cages and bone grafts.''' For spinal decompressions involving a discectomy, the surgeon will remove a part or all of the intervertebral disc. If so, it is necessary to fill the empty disc space between the vertebral body with either a bone graft (e.g., autograft, allograft) or an interbody cage to restore the height of the spine. These devices are cylindrical or square-shaped and often threaded for increased stability. The interbody cage or bone graft is inserted by distracting the space between the discs. Some interbody cages are expandable, which allows for a more optimal fit.

	'''2. Ondontoid (dens) fracture'''		'''2. Ondontoid (dens) fracture'''

Wdoyon: /* Lumbosacral spine surgery */

2022-01-27T20:01:32Z

Lumbosacral spine surgery

← Older revision		Revision as of 15:01, 27 January 2022
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	The lumbar plexus is at risk for nerve injury during a fusion. At the upper lumbar levels, the nerves of the lumbar plexus are in most cases posterior to the surgical site. But the risk for injury to the lumbar plexus becomes greater if the surgical approach is below the L3 level. IONM of lower lumbar and sacral regions involves the monitoring of spinal nerve root function, primarily with EMG recordings and SSEPs. Ascending and descending spinal cord function is monitored with SSEPs and MEPs, respectively. SSEPs are particularly important because the surgical approach for most lower lumbar surgeries is posterior, which has a greater potential to damage spinal nerve roots that enter the dorsal horn of the spinal column. For upper lumbar cases (L1-2), MEPs along with SSEPs are essential for monitoring spinal cord function.		The lumbar plexus is at risk for nerve injury during a fusion. At the upper lumbar levels, the nerves of the lumbar plexus are in most cases posterior to the surgical site. But the risk for injury to the lumbar plexus becomes greater if the surgical approach is below the L3 level. IONM of lower lumbar and sacral regions involves the monitoring of spinal nerve root function, primarily with EMG recordings and SSEPs. Ascending and descending spinal cord function is monitored with SSEPs and MEPs, respectively. SSEPs are particularly important because the surgical approach for most lower lumbar surgeries is posterior, which has a greater potential to damage spinal nerve roots that enter the dorsal horn of the spinal column. For upper lumbar cases (L1-2), MEPs along with SSEPs are essential for monitoring spinal cord function.

	'''Pedicle screw testing'''. After insertion of the pedicle screws, triggered EMG is used to determine whether there is a medial breach of the pedicle bone. Pedicle screws are tested by applying direct electrical current (0-50 mA cathodal stimulation) to each screw. The current return is placed in tissue on the contralateral side of the spine, which makes the current run through the spinal nerves between the screw to the anode. A screw that is well positioned in the pedicle bone will be well insulated by the bone tissue and have high stimulus thresholds. If the screw penetrates the bone, the applied current may activate the nearby nerve roots, resulting in compound muscle action potentials from muscles innervated by motor nerves at the level of the screw. CMAPs that are triggered by stimulus thresholds less than 10 mA in intensity are worrisome and may indicate a pedicle breach, which may cause irritation or injury to the nerve tissue. However, stimulus thresholds can vary from person to person. Individuals with osteoporosis may have lower stimulus thresholds because of the poor bone density. Also, the current can take different paths through the tissue that depend on the surgical environment. A wet surgical field may result in current shunting, which could increase the threshold needed to activate the nerve roots. Current shunting is also an issue for minimally invasive surgeries in which the screws are inserted into the pedicles percutaneously. Here, the screws are inserted through the skin and soft tissue with the aid of fluoroscopy. When the pedicle screws are tested, the current is shunted to the surrounding tissue, which typically results in higher stimulus thresholds.		'''Pedicle screw testing'''. After insertion of the pedicle screws, triggered EMG is used to determine whether there is a medial breach of the pedicle bone. Pedicle screws are tested by applying direct electrical current (0-50 mA cathodal stimulation) to each screw. The current return is placed in tissue on the contralateral side of the spine, which makes the current run through the spinal nerves between the screw and the anode. A screw that is well positioned in the pedicle bone will be well insulated by the bone tissue and have high stimulus thresholds. If the screw penetrates the bone, the applied current may activate the nearby nerve roots, resulting in compound muscle action potentials from muscles innervated by motor nerves at the level of the screw. CMAPs that are triggered by stimulus thresholds less than 10 mA in intensity are worrisome and may indicate a pedicle breach, which may cause irritation or injury to the nerve tissue. However, stimulus thresholds can vary from person to person. Individuals with osteoporosis may have lower stimulus thresholds because of the poor bone density. Also, the current can take different paths through the tissue that depend on the surgical environment. A wet surgical field may result in current shunting, which could increase the threshold needed to activate the nerve roots. Current shunting is also an issue for minimally invasive surgeries in which the screws are inserted into the pedicles percutaneously. Here, the screws are inserted through the skin and soft tissue with the aid of fluoroscopy. When the pedicle screws are tested, the current is shunted to the surrounding tissue, which typically results in higher stimulus thresholds.

	'''Lateral lumbar interbody fusions'''. This procedure is considered minimally invasive. In contrast to posterior lumbar fusion, the incision for a lateral lumbar fusion approaches the lumbar spine from a far lateral approach that passes through the psoas muscles. The main advantages of this technique is that injury to the posterior spinal ligaments is avoided and that larger cages can be inserted for greater stability of the interbody device. However, there is a higher risk of injury to the lumbar plexus using this approach due to direct injury or prolonged use of retractors. While nerve injuries tend to be temporary, there is a risk for permanent motor and sensory deficits due to injury of the femoral nerve. IONM strategies for monitoring of LLIFs include a combination of EMG, transcranial MEPs and SSEPs of the saphenous nerve. The saphenous nerve is the largest terminal cutaneous branch of the femoral nerve.		'''Lateral lumbar interbody fusions'''. This procedure is considered minimally invasive. In contrast to posterior lumbar fusion, the incision for a lateral lumbar fusion approaches the lumbar spine from a far lateral approach that passes through the psoas muscles. The main advantages of this technique is that injury to the posterior spinal ligaments is avoided and that larger cages can be inserted for greater stability of the interbody device. However, there is a higher risk of injury to the lumbar plexus using this approach due to direct injury or prolonged use of retractors. While nerve injuries tend to be temporary, there is a risk for permanent motor and sensory deficits due to injury of the femoral nerve. IONM strategies for monitoring of LLIFs include a combination of EMG, transcranial MEPs and SSEPs of the saphenous nerve. The saphenous nerve is the largest terminal cutaneous branch of the femoral nerve.

Wdoyon: /* Lumbosacral spine surgery */

2022-01-27T20:00:21Z

Lumbosacral spine surgery

← Older revision		Revision as of 15:00, 27 January 2022
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	==Lumbosacral spine surgery==		==Lumbosacral spine surgery==
	'''Posterior lumbosacral interbody fusions'''. Lumbosacral fusions are performed to stabilize the spine and relieve pressure on the exiting nerve roots. The lumbosacral spine includes the L1-L5 levels as well as the sacrum (S1-S5 are five fused segments). Compression of the exiting nerve roots, or the spinal cord at the L1-2 level, can cause symptoms like pain, numbness and weakness in the legs. A posterior lumbar fusion involves the connection of two or more vertebrae by inserting screws into the pedicle bones and fastening them together with rod instrumentation. Surgeons will use different size screws depending on the spinal level on which they are working, the size and morphology of the patient's vertebral bones, etc. The fixation of screws into the lumbar spinal column requires the use of rods to join them together. A single rod is used to connect all the screws on each side of the spinal column and tightened into place. Therefore, there are two sets of rods, one for each side of the spine.		'''Posterior lumbosacral interbody fusions'''. Lumbosacral fusions are usually performed to stabilize the spine and relieve pressure on the exiting nerve roots. The lumbosacral spine includes the L1-L5 levels as well as the sacrum (S1-S5 are five fused segments). Compression of the exiting nerve roots, or the spinal cord at the L1-2 level, can cause symptoms like pain, numbness and weakness in the legs. A posterior lumbar fusion involves the connection of two or more vertebrae by inserting screws into the pedicle bones and fastening them together with rod instrumentation. Surgeons will use different size screws depending on the spinal level on which they are working, the size and morphology of the patient's vertebral bones, etc. The fixation of screws into the lumbar spinal column requires the use of rods to join them together. A single rod is used to connect all the screws on each side of the spinal column and tightened into place. Therefore, there are two sets of rods, one for each side of the spine.

	Problems of the lumbar spine that require a fusion include degenerative disc disease, disc herniation, spondylolisthesis, spondylosis, vertebral fractures, spinal tumors, lordosis and scoliosis.		Problems of the lumbar spine that require a fusion include degenerative disc disease, disc herniation, spondylolisthesis, spondylosis, vertebral fractures, spinal tumors, lordosis and scoliosis.

	The lumbar plexus is at risk for nerve injury during a fusion. At the upper lumbar levels, the nerves of the lumbar plexus are in most cases posterior to the surgical site. But the risk for injury to the lumbar plexus becomes greater if the surgical ~~site~~ is below the L3 level. IONM of lower lumbar and sacral regions involves the monitoring of spinal nerve root function, primarily with EMG recordings. Ascending and descending spinal cord function is ~~also~~ monitored with SSEPs and MEPs, respectively. SSEPs are particularly important because the surgical approach for most lower lumbar surgeries is posterior, which has a greater potential to damage spinal nerve roots that enter the dorsal horn of the spinal column. For upper lumbar cases (L1-2), MEPs along with SSEPs are essential for monitoring spinal cord function.		The lumbar plexus is at risk for nerve injury during a fusion. At the upper lumbar levels, the nerves of the lumbar plexus are in most cases posterior to the surgical site. But the risk for injury to the lumbar plexus becomes greater if the surgical approach is below the L3 level. IONM of lower lumbar and sacral regions involves the monitoring of spinal nerve root function, primarily with EMG recordings and SSEPs. Ascending and descending spinal cord function is monitored with SSEPs and MEPs, respectively. SSEPs are particularly important because the surgical approach for most lower lumbar surgeries is posterior, which has a greater potential to damage spinal nerve roots that enter the dorsal horn of the spinal column. For upper lumbar cases (L1-2), MEPs along with SSEPs are essential for monitoring spinal cord function.

	'''Pedicle screw testing'''. After insertion of the pedicle screws, triggered EMG is used to determine whether there is a medial breach of the pedicle bone. Pedicle screws are tested by applying direct electrical current (0-50 mA cathodal stimulation) to each screw. The current return is placed in tissue on the contralateral side of the spine, which makes the current run through the spinal nerves between the screw to the anode. A screw that is well positioned in the pedicle bone will be well insulated by the bone tissue and have high stimulus thresholds. If the screw penetrates the bone, the applied current may activate the nearby nerve roots, resulting in compound muscle action potentials from muscles innervated by motor nerves at the level of the screw. CMAPs that are triggered by stimulus thresholds less than 10 mA in intensity are worrisome and may indicate a pedicle breach, which may cause irritation or injury to the nerve tissue. However, stimulus thresholds can vary from person to person. Individuals with osteoporosis may have lower stimulus thresholds because of the poor bone density. Also, the current can take different paths through the tissue that depend on the surgical environment. A wet surgical field may result in current shunting, which could increase the threshold needed to activate the nerve roots. Current shunting is also an issue for minimally invasive surgeries in which the screws are inserted into the pedicles percutaneously. Here, the screws are inserted through the skin and soft tissue with the aid of fluoroscopy. When the pedicle screws are tested, the current is shunted to the surrounding tissue, which typically results in higher stimulus thresholds.		'''Pedicle screw testing'''. After insertion of the pedicle screws, triggered EMG is used to determine whether there is a medial breach of the pedicle bone. Pedicle screws are tested by applying direct electrical current (0-50 mA cathodal stimulation) to each screw. The current return is placed in tissue on the contralateral side of the spine, which makes the current run through the spinal nerves between the screw to the anode. A screw that is well positioned in the pedicle bone will be well insulated by the bone tissue and have high stimulus thresholds. If the screw penetrates the bone, the applied current may activate the nearby nerve roots, resulting in compound muscle action potentials from muscles innervated by motor nerves at the level of the screw. CMAPs that are triggered by stimulus thresholds less than 10 mA in intensity are worrisome and may indicate a pedicle breach, which may cause irritation or injury to the nerve tissue. However, stimulus thresholds can vary from person to person. Individuals with osteoporosis may have lower stimulus thresholds because of the poor bone density. Also, the current can take different paths through the tissue that depend on the surgical environment. A wet surgical field may result in current shunting, which could increase the threshold needed to activate the nerve roots. Current shunting is also an issue for minimally invasive surgeries in which the screws are inserted into the pedicles percutaneously. Here, the screws are inserted through the skin and soft tissue with the aid of fluoroscopy. When the pedicle screws are tested, the current is shunted to the surrounding tissue, which typically results in higher stimulus thresholds.

Wdoyon: /* Lumbosacral spine surgery */

2022-01-27T19:38:22Z

Lumbosacral spine surgery

← Older revision		Revision as of 14:38, 27 January 2022
Line 27:		Line 27:

	==Lumbosacral spine surgery==		==Lumbosacral spine surgery==
	'''Posterior ~~lumbar-sacral~~ interbody fusions'''. ~~Posterior lumbosacral~~ fusions are ~~common surgeries~~ and ~~can include~~ the L1-~~5 lumbar~~ levels as well as the ~~S1 sacral level S1~~ (S1-S5 are five fused segments). ~~Lumbosacral fusions are performed to relieve pressure on~~ the nerve roots or ~~to stabilize~~ the ~~spine~~, ~~which~~ can cause symptoms like pain, numbness and weakness in the legs. A posterior lumbar fusion involves the connection of two or more vertebrae by inserting screws into the pedicle bones and fastening them together with rod instrumentation. Surgeons will use different size screws depending on the spinal level on which they are working, the size and morphology of the patient's vertebral bones, etc. The fixation of screws into the lumbar spinal column requires the use of rods to join them together. A single rod is used to connect all the screws on each side of the spinal column and tightened into place. Therefore, there are two sets of rods, one for each side of the spine.		'''Posterior lumbosacral interbody fusions'''. Lumbosacral fusions are performed to stabilize the spine and relieve pressure on the exiting nerve roots. The lumbosacral spine includes the L1-L5 levels as well as the sacrum (S1-S5 are five fused segments). Compression of the exiting nerve roots, or the spinal cord at the L1-2 level, can cause symptoms like pain, numbness and weakness in the legs. A posterior lumbar fusion involves the connection of two or more vertebrae by inserting screws into the pedicle bones and fastening them together with rod instrumentation. Surgeons will use different size screws depending on the spinal level on which they are working, the size and morphology of the patient's vertebral bones, etc. The fixation of screws into the lumbar spinal column requires the use of rods to join them together. A single rod is used to connect all the screws on each side of the spinal column and tightened into place. Therefore, there are two sets of rods, one for each side of the spine.

	~~Spinal problems~~ that require a fusion include degenerative disc disease, disc herniation, spondylolisthesis, spondylosis, vertebral fractures, spinal tumors, and scoliosis.		Problems of the lumbar spine that require a fusion include degenerative disc disease, disc herniation, spondylolisthesis, spondylosis, vertebral fractures, spinal tumors, lordosis and scoliosis.

	IONM of lower lumbar and sacral regions ~~(L3 and below)~~ involves the monitoring of spinal nerve root function, primarily with EMG recordings. Ascending and descending spinal cord function is also monitored with SSEPs and MEPs, respectively. SSEPs are particularly important because the surgical approach for most lower lumbar surgeries is posterior, which has a greater potential to damage spinal nerve roots that enter the dorsal horn of the spinal column. For upper lumbar cases (L1-2), MEPs along with SSEPs are essential for monitoring spinal cord function.		The lumbar plexus is at risk for nerve injury during a fusion. At the upper lumbar levels, the nerves of the lumbar plexus are in most cases posterior to the surgical site. But the risk for injury to the lumbar plexus becomes greater if the surgical site is below the L3 level. IONM of lower lumbar and sacral regions involves the monitoring of spinal nerve root function, primarily with EMG recordings. Ascending and descending spinal cord function is also monitored with SSEPs and MEPs, respectively. SSEPs are particularly important because the surgical approach for most lower lumbar surgeries is posterior, which has a greater potential to damage spinal nerve roots that enter the dorsal horn of the spinal column. For upper lumbar cases (L1-2), MEPs along with SSEPs are essential for monitoring spinal cord function.

	'''Pedicle screw testing'''. After insertion of the pedicle screws, triggered EMG is used to determine whether there is a medial breach of the pedicle bone. Pedicle screws are tested by applying direct electrical current (0-50 mA cathodal stimulation) to each screw. The current return is placed in tissue on the contralateral side of the spine, which makes the current run through the spinal nerves between the screw to the anode. A screw that is well positioned in the pedicle bone will be well insulated by the bone tissue and have high stimulus thresholds. If the screw penetrates the bone, the applied current may activate the nearby nerve roots, resulting in compound muscle action potentials from muscles innervated by motor nerves at the level of the screw. CMAPs that are triggered by stimulus thresholds less than 10 mA in intensity are worrisome and may indicate a pedicle breach, which may cause irritation or injury to the nerve tissue. However, stimulus thresholds can vary from person to person. Individuals with osteoporosis may have lower stimulus thresholds because of the poor bone density. Also, the current can take different paths through the tissue that depend on the surgical environment. A wet surgical field may result in current shunting, which could increase the threshold needed to activate the nerve roots. Current shunting is also an issue for minimally invasive surgeries in which the screws are inserted into the pedicles percutaneously. Here, the screws are inserted through the skin and soft tissue with the aid of fluoroscopy. When the pedicle screws are tested, the current is shunted to the surrounding tissue, which typically results in higher stimulus thresholds.		'''Pedicle screw testing'''. After insertion of the pedicle screws, triggered EMG is used to determine whether there is a medial breach of the pedicle bone. Pedicle screws are tested by applying direct electrical current (0-50 mA cathodal stimulation) to each screw. The current return is placed in tissue on the contralateral side of the spine, which makes the current run through the spinal nerves between the screw to the anode. A screw that is well positioned in the pedicle bone will be well insulated by the bone tissue and have high stimulus thresholds. If the screw penetrates the bone, the applied current may activate the nearby nerve roots, resulting in compound muscle action potentials from muscles innervated by motor nerves at the level of the screw. CMAPs that are triggered by stimulus thresholds less than 10 mA in intensity are worrisome and may indicate a pedicle breach, which may cause irritation or injury to the nerve tissue. However, stimulus thresholds can vary from person to person. Individuals with osteoporosis may have lower stimulus thresholds because of the poor bone density. Also, the current can take different paths through the tissue that depend on the surgical environment. A wet surgical field may result in current shunting, which could increase the threshold needed to activate the nerve roots. Current shunting is also an issue for minimally invasive surgeries in which the screws are inserted into the pedicles percutaneously. Here, the screws are inserted through the skin and soft tissue with the aid of fluoroscopy. When the pedicle screws are tested, the current is shunted to the surrounding tissue, which typically results in higher stimulus thresholds.

	'''Lateral lumbar interbody fusions'''. This procedure is considered minimally invasive. In contrast to posterior lumbar fusion, the incision for a lateral lumbar fusion approaches the lumbar spine from a far lateral approach that passes through the psoas muscles. The main advantages of this technique is that injury to the posterior spinal ligaments is avoided and that larger cages can be inserted for greater stability of the interbody device. However, there is a higher risk of injury to the lumbar plexus using this approach. While nerve injuries tend to be temporary, there is a risk for permanent motor and sensory deficits due to injury of the femoral nerve. IONM strategies for monitoring of LLIFs include a combination of EMG, transcranial MEPs and SSEPs of the saphenous nerve. The saphenous nerve is the largest terminal cutaneous branch of the femoral nerve.		'''Lateral lumbar interbody fusions'''. This procedure is considered minimally invasive. In contrast to posterior lumbar fusion, the incision for a lateral lumbar fusion approaches the lumbar spine from a far lateral approach that passes through the psoas muscles. The main advantages of this technique is that injury to the posterior spinal ligaments is avoided and that larger cages can be inserted for greater stability of the interbody device. However, there is a higher risk of injury to the lumbar plexus using this approach due to direct injury or prolonged use of retractors. While nerve injuries tend to be temporary, there is a risk for permanent motor and sensory deficits due to injury of the femoral nerve. IONM strategies for monitoring of LLIFs include a combination of EMG, transcranial MEPs and SSEPs of the saphenous nerve. The saphenous nerve is the largest terminal cutaneous branch of the femoral nerve.

	==Cervical spine surgery==		==Cervical spine surgery==

Wdoyon: /* Thoracic spinal surgery */

2022-01-21T03:51:58Z

Thoracic spinal surgery

← Older revision		Revision as of 22:51, 20 January 2022
Line 47:		Line 47:
	Insertion of pedicle screw in the thoracic spine remains technically challenging due to the smaller size and more complex morphology of the thoracic pedicle bone compared to the lumbar pedicle bone. The Roy-Camille method is the most commonly used technique for inserting pedicle screws into the thoracic spine, but there remains a high incidence of pedicle bone breach. Screw placement with a partial laminectomy may reduce the incidence of pedicle bone breach [Spine 1998;23(9):1065-8].		Insertion of pedicle screw in the thoracic spine remains technically challenging due to the smaller size and more complex morphology of the thoracic pedicle bone compared to the lumbar pedicle bone. The Roy-Camille method is the most commonly used technique for inserting pedicle screws into the thoracic spine, but there remains a high incidence of pedicle bone breach. Screw placement with a partial laminectomy may reduce the incidence of pedicle bone breach [Spine 1998;23(9):1065-8].

	For IONM of thoracic spinal surgeries, such as an instrumented fusion or a laminectomy, we monitor spinal cord and nerve roots function, similar to upper lumbar surgeries. For thoracic fusions, the pedicle screws are not always tested with electrical stimulation because of the smaller size of the pedicle bone in the thoracic spine. The stimulus thresholds tend to be lower compared to those in the lumbar spine, making it difficult to determine a criterion for a pedicle breach. However, we are most concerned about a medial breach due to the proximity to the spinal cord. Although the thresholds for thoracic pedicle screws are lower in general, it may be necessary to increase the stimulation intensity to see a spinal cord response, using protocols that are similar to those used to generate MEPs. One study found that triggered EMG was more effective at detecting medial breaches at the T10-12 level compared to the T2-9 level (Samdani et al., Eur Spine J. 2011 Jun; 20(6): 869–874).		For IONM of thoracic spinal surgeries, such as an instrumented fusion or a laminectomy, we monitor spinal cord and nerve roots function, similar to upper lumbar surgeries. For thoracic fusions, the pedicle screws are not always tested with electrical stimulation because of the smaller size of the pedicle bone in the thoracic spine. The stimulus thresholds tend to be lower compared to those in the lumbar spine, making it difficult to determine a criterion for a pedicle breach. However, we are most concerned about a medial breach due to the proximity to the spinal cord. Although the thresholds for thoracic pedicle screws are lower in general, it may be necessary to increase the stimulation intensity to see a spinal cord response, using pulse-train protocols that are similar to those used to generate MEPs. One study found that pedicle screw testing with triggered EMG was more effective at detecting medial breaches at the T10-12 level compared to the T2-9 level (Samdani et al., Eur Spine J. 2011 Jun; 20(6): 869–874). Alternatively, another approach to direct pedicle screw testing has shown that pulse-train stimulation inside of the pedicle track with electromyography from lower limb muscles was very effective at detecting medial breaches from misplaced screws (Calancie et al., J Neurosurg Spine 20:675–691, 2014).

	==Scoliosis surgery==		==Scoliosis surgery==

Wdoyon: /* Thoracic spinal surgery */

2022-01-21T03:37:10Z

Thoracic spinal surgery

← Older revision		Revision as of 22:37, 20 January 2022
Line 47:		Line 47:
	Insertion of pedicle screw in the thoracic spine remains technically challenging due to the smaller size and more complex morphology of the thoracic pedicle bone compared to the lumbar pedicle bone. The Roy-Camille method is the most commonly used technique for inserting pedicle screws into the thoracic spine, but there remains a high incidence of pedicle bone breach. Screw placement with a partial laminectomy may reduce the incidence of pedicle bone breach [Spine 1998;23(9):1065-8].		Insertion of pedicle screw in the thoracic spine remains technically challenging due to the smaller size and more complex morphology of the thoracic pedicle bone compared to the lumbar pedicle bone. The Roy-Camille method is the most commonly used technique for inserting pedicle screws into the thoracic spine, but there remains a high incidence of pedicle bone breach. Screw placement with a partial laminectomy may reduce the incidence of pedicle bone breach [Spine 1998;23(9):1065-8].

	For IONM of thoracic spinal surgeries, such as an instrumented fusion or a laminectomy, we monitor spinal cord and nerve roots function, similar to upper lumbar surgeries. For thoracic fusions, the pedicle screws are not always tested with electrical stimulation because of the smaller size of the pedicle bone in the thoracic spine. The stimulus thresholds tend to be lower compared to those in the lumbar spine, making it difficult to determine a criterion for a pedicle breach. However, we are most concerned about a medial breach due to the proximity to the spinal cord. Although the thresholds for thoracic pedicle screws are lower in general, it may be necessary to increase the stimulation intensity to see a spinal cord response, using protocols that are similar to those used to generate MEPs.		For IONM of thoracic spinal surgeries, such as an instrumented fusion or a laminectomy, we monitor spinal cord and nerve roots function, similar to upper lumbar surgeries. For thoracic fusions, the pedicle screws are not always tested with electrical stimulation because of the smaller size of the pedicle bone in the thoracic spine. The stimulus thresholds tend to be lower compared to those in the lumbar spine, making it difficult to determine a criterion for a pedicle breach. However, we are most concerned about a medial breach due to the proximity to the spinal cord. Although the thresholds for thoracic pedicle screws are lower in general, it may be necessary to increase the stimulation intensity to see a spinal cord response, using protocols that are similar to those used to generate MEPs. One study found that triggered EMG was more effective at detecting medial breaches at the T10-12 level compared to the T2-9 level (Samdani et al., Eur Spine J. 2011 Jun; 20(6): 869–874).

	==Scoliosis surgery==		==Scoliosis surgery==

Wdoyon: /* Thoracic spinal surgery */

2022-01-21T03:28:23Z

Thoracic spinal surgery

← Older revision		Revision as of 22:28, 20 January 2022
Line 47:		Line 47:
	Insertion of pedicle screw in the thoracic spine remains technically challenging due to the smaller size and more complex morphology of the thoracic pedicle bone compared to the lumbar pedicle bone. The Roy-Camille method is the most commonly used technique for inserting pedicle screws into the thoracic spine, but there remains a high incidence of pedicle bone breach. Screw placement with a partial laminectomy may reduce the incidence of pedicle bone breach [Spine 1998;23(9):1065-8].		Insertion of pedicle screw in the thoracic spine remains technically challenging due to the smaller size and more complex morphology of the thoracic pedicle bone compared to the lumbar pedicle bone. The Roy-Camille method is the most commonly used technique for inserting pedicle screws into the thoracic spine, but there remains a high incidence of pedicle bone breach. Screw placement with a partial laminectomy may reduce the incidence of pedicle bone breach [Spine 1998;23(9):1065-8].

	IONM of ~~the~~ thoracic ~~procedures~~, such as ~~fusions and laminectomies for placement of~~ spinal cord ~~stimulators~~, is similar to upper lumbar surgeries ~~with regard to monitoring of spinal cord and nerve root function~~. For thoracic fusions, the pedicle screws are not always tested with electrical stimulation because of the smaller size of the pedicle bone in the thoracic spine. The stimulus thresholds tend to be ~~much~~ lower compared to those in the lumbar spine, making it difficult to determine a criterion for a pedicle breach.		For IONM of thoracic spinal surgeries, such as an instrumented fusion or a laminectomy, we monitor spinal cord and nerve roots function, similar to upper lumbar surgeries. For thoracic fusions, the pedicle screws are not always tested with electrical stimulation because of the smaller size of the pedicle bone in the thoracic spine. The stimulus thresholds tend to be lower compared to those in the lumbar spine, making it difficult to determine a criterion for a pedicle breach. However, we are most concerned about a medial breach due to the proximity to the spinal cord. Although the thresholds for thoracic pedicle screws are lower in general, it may be necessary to increase the stimulation intensity to see a spinal cord response, using protocols that are similar to those used to generate MEPs.

	==Scoliosis surgery==		==Scoliosis surgery==

Wdoyon: /* Lumbosacral spine surgery */

2022-01-14T03:52:56Z

Lumbosacral spine surgery

← Older revision		Revision as of 22:52, 13 January 2022
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	==Lumbosacral spine surgery==		==Lumbosacral spine surgery==
	""Posterior lumbar-sacral interbody fusions"". Posterior lumbosacral fusions are common surgeries and can include the L1-5 lumbar levels as well as the S1 sacral level S1 (S1-S5 are five fused segments). Lumbosacral fusions are performed to relieve pressure on the nerve roots or to stabilize the spine, which can cause symptoms like pain, numbness and weakness in the legs. A posterior lumbar fusion involves the connection of two or more vertebrae by inserting screws into the pedicle bones and fastening them together with rod instrumentation. Surgeons will use different size screws depending on the spinal level on which they are working, the size and morphology of the patient's vertebral bones, etc. The fixation of screws into the lumbar spinal column requires the use of rods to join them together. A single rod is used to connect all the screws on each side of the spinal column and tightened into place. Therefore, there are two sets of rods, one for each side of the spine.		'''Posterior lumbar-sacral interbody fusions'''. Posterior lumbosacral fusions are common surgeries and can include the L1-5 lumbar levels as well as the S1 sacral level S1 (S1-S5 are five fused segments). Lumbosacral fusions are performed to relieve pressure on the nerve roots or to stabilize the spine, which can cause symptoms like pain, numbness and weakness in the legs. A posterior lumbar fusion involves the connection of two or more vertebrae by inserting screws into the pedicle bones and fastening them together with rod instrumentation. Surgeons will use different size screws depending on the spinal level on which they are working, the size and morphology of the patient's vertebral bones, etc. The fixation of screws into the lumbar spinal column requires the use of rods to join them together. A single rod is used to connect all the screws on each side of the spinal column and tightened into place. Therefore, there are two sets of rods, one for each side of the spine.

	Spinal problems that require a fusion include degenerative disc disease, disc herniation, spondylolisthesis, spondylosis, vertebral fractures, spinal tumors, and scoliosis.		Spinal problems that require a fusion include degenerative disc disease, disc herniation, spondylolisthesis, spondylosis, vertebral fractures, spinal tumors, and scoliosis.
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	'''Pedicle screw testing'''. After insertion of the pedicle screws, triggered EMG is used to determine whether there is a medial breach of the pedicle bone. Pedicle screws are tested by applying direct electrical current (0-50 mA cathodal stimulation) to each screw. The current return is placed in tissue on the contralateral side of the spine, which makes the current run through the spinal nerves between the screw to the anode. A screw that is well positioned in the pedicle bone will be well insulated by the bone tissue and have high stimulus thresholds. If the screw penetrates the bone, the applied current may activate the nearby nerve roots, resulting in compound muscle action potentials from muscles innervated by motor nerves at the level of the screw. CMAPs that are triggered by stimulus thresholds less than 10 mA in intensity are worrisome and may indicate a pedicle breach, which may cause irritation or injury to the nerve tissue. However, stimulus thresholds can vary from person to person. Individuals with osteoporosis may have lower stimulus thresholds because of the poor bone density. Also, the current can take different paths through the tissue that depend on the surgical environment. A wet surgical field may result in current shunting, which could increase the threshold needed to activate the nerve roots. Current shunting is also an issue for minimally invasive surgeries in which the screws are inserted into the pedicles percutaneously. Here, the screws are inserted through the skin and soft tissue with the aid of fluoroscopy. When the pedicle screws are tested, the current is shunted to the surrounding tissue, which typically results in higher stimulus thresholds.		'''Pedicle screw testing'''. After insertion of the pedicle screws, triggered EMG is used to determine whether there is a medial breach of the pedicle bone. Pedicle screws are tested by applying direct electrical current (0-50 mA cathodal stimulation) to each screw. The current return is placed in tissue on the contralateral side of the spine, which makes the current run through the spinal nerves between the screw to the anode. A screw that is well positioned in the pedicle bone will be well insulated by the bone tissue and have high stimulus thresholds. If the screw penetrates the bone, the applied current may activate the nearby nerve roots, resulting in compound muscle action potentials from muscles innervated by motor nerves at the level of the screw. CMAPs that are triggered by stimulus thresholds less than 10 mA in intensity are worrisome and may indicate a pedicle breach, which may cause irritation or injury to the nerve tissue. However, stimulus thresholds can vary from person to person. Individuals with osteoporosis may have lower stimulus thresholds because of the poor bone density. Also, the current can take different paths through the tissue that depend on the surgical environment. A wet surgical field may result in current shunting, which could increase the threshold needed to activate the nerve roots. Current shunting is also an issue for minimally invasive surgeries in which the screws are inserted into the pedicles percutaneously. Here, the screws are inserted through the skin and soft tissue with the aid of fluoroscopy. When the pedicle screws are tested, the current is shunted to the surrounding tissue, which typically results in higher stimulus thresholds.

	""Lateral lumbar interbody fusions"". This procedure is considered minimally invasive. In contrast to posterior lumbar fusion, the incision for a lateral lumbar fusion approaches the lumbar spine from a far lateral approach that passes through the psoas muscles. The main advantages of this technique is that injury to the posterior spinal ligaments is avoided and that larger cages can be inserted for greater stability of the interbody device. However, there is a higher risk of injury to the lumbar plexus using this approach. While nerve injuries tend to be temporary, there is a risk for permanent motor and sensory deficits due to injury of the femoral nerve. IONM strategies for monitoring of LLIFs include a combination of EMG, transcranial MEPs and SSEPs of the saphenous nerve. The saphenous nerve is the largest terminal cutaneous branch of the femoral nerve.		'''Lateral lumbar interbody fusions'''. This procedure is considered minimally invasive. In contrast to posterior lumbar fusion, the incision for a lateral lumbar fusion approaches the lumbar spine from a far lateral approach that passes through the psoas muscles. The main advantages of this technique is that injury to the posterior spinal ligaments is avoided and that larger cages can be inserted for greater stability of the interbody device. However, there is a higher risk of injury to the lumbar plexus using this approach. While nerve injuries tend to be temporary, there is a risk for permanent motor and sensory deficits due to injury of the femoral nerve. IONM strategies for monitoring of LLIFs include a combination of EMG, transcranial MEPs and SSEPs of the saphenous nerve. The saphenous nerve is the largest terminal cutaneous branch of the femoral nerve.

	==Cervical spine surgery==		==Cervical spine surgery==

Wdoyon: /* Lumbosacral spine surgery */

2022-01-14T03:51:56Z

Lumbosacral spine surgery

← Older revision		Revision as of 22:51, 13 January 2022
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	==Lumbosacral spine surgery==		==Lumbosacral spine surgery==
	~~Lumbosacral spinal~~ fusions are common surgeries and can include L1-5 lumbar levels as well as the S1 sacral level S1 (S1-S5 are five fused segments). Lumbosacral fusions are performed to relieve pressure on the nerve roots or to stabilize the spine, which can cause symptoms like pain, numbness and weakness in the legs. A posterior lumbar fusion involves the connection of two or more vertebrae by inserting screws into the pedicle bones and fastening them together with rod instrumentation. Surgeons will use different size screws depending on the spinal level on which they are working, the size and morphology of the patient's vertebral bones, etc. The fixation of screws into the lumbar spinal column requires the use of rods to join them together. A single rod is used to connect all the screws on each side of the spinal column and tightened into place. Therefore, there are two sets of rods, one for each side of the spine.		""Posterior lumbar-sacral interbody fusions"". Posterior lumbosacral fusions are common surgeries and can include the L1-5 lumbar levels as well as the S1 sacral level S1 (S1-S5 are five fused segments). Lumbosacral fusions are performed to relieve pressure on the nerve roots or to stabilize the spine, which can cause symptoms like pain, numbness and weakness in the legs. A posterior lumbar fusion involves the connection of two or more vertebrae by inserting screws into the pedicle bones and fastening them together with rod instrumentation. Surgeons will use different size screws depending on the spinal level on which they are working, the size and morphology of the patient's vertebral bones, etc. The fixation of screws into the lumbar spinal column requires the use of rods to join them together. A single rod is used to connect all the screws on each side of the spinal column and tightened into place. Therefore, there are two sets of rods, one for each side of the spine.

	Spinal problems that require a fusion include degenerative disc disease, disc herniation, spondylolisthesis, spondylosis, vertebral fractures, spinal tumors, and scoliosis.		Spinal problems that require a fusion include degenerative disc disease, disc herniation, spondylolisthesis, spondylosis, vertebral fractures, spinal tumors, and scoliosis.
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	IONM of lower lumbar and sacral regions (L3 and below) involves the monitoring of spinal nerve root function, primarily with EMG recordings. Ascending and descending spinal cord function is also monitored with SSEPs and MEPs, respectively. SSEPs are particularly important because the surgical approach for most lower lumbar surgeries is posterior, which has a greater potential to damage spinal nerve roots that enter the dorsal horn of the spinal column. For upper lumbar cases (L1-2), MEPs along with SSEPs are essential for monitoring spinal cord function.		IONM of lower lumbar and sacral regions (L3 and below) involves the monitoring of spinal nerve root function, primarily with EMG recordings. Ascending and descending spinal cord function is also monitored with SSEPs and MEPs, respectively. SSEPs are particularly important because the surgical approach for most lower lumbar surgeries is posterior, which has a greater potential to damage spinal nerve roots that enter the dorsal horn of the spinal column. For upper lumbar cases (L1-2), MEPs along with SSEPs are essential for monitoring spinal cord function.

	'''Pedicle screw testing'''. After insertion of the pedicle screws, triggered EMG is used to determine whether there is a medial breach of the pedicle bone. Pedicle screws are tested by applying direct electrical current (0-50 mA cathodal stimulation) to each screw. The current return is placed in tissue on the contralateral side of the spine, which makes the current run through the spinal nerves between the screw to the anode. A screw that is well positioned in the pedicle bone will be well insulated by the bone tissue and have high stimulus thresholds. If the screw penetrates the bone, the applied current may activate the nearby nerve roots, resulting in compound muscle action potentials from muscles innervated by motor nerves at the level of the screw. CMAPs that are triggered by stimulus thresholds less than 10 mA in intensity are worrisome and may indicate a pedicle breach, which may cause irritation or injury to the nerve tissue. However, stimulus thresholds can vary from person to person. Individuals with osteoporosis may have lower stimulus thresholds because of the poor bone density. Also, the current can take different paths through the tissue that depend on the surgical environment. A wet surgical field may result in current shunting, which could increase the threshold needed to activate the nerve roots. Current shunting is also an issue for minimally invasive surgeries in which the screws are inserted into the pedicles ~~by a percutaneous approach~~. Here, the screws are inserted through the skin and soft tissue with the aid of fluoroscopy. When the pedicle screws are tested, the current is shunted to the surrounding tissue, which typically results in higher stimulus thresholds.		'''Pedicle screw testing'''. After insertion of the pedicle screws, triggered EMG is used to determine whether there is a medial breach of the pedicle bone. Pedicle screws are tested by applying direct electrical current (0-50 mA cathodal stimulation) to each screw. The current return is placed in tissue on the contralateral side of the spine, which makes the current run through the spinal nerves between the screw to the anode. A screw that is well positioned in the pedicle bone will be well insulated by the bone tissue and have high stimulus thresholds. If the screw penetrates the bone, the applied current may activate the nearby nerve roots, resulting in compound muscle action potentials from muscles innervated by motor nerves at the level of the screw. CMAPs that are triggered by stimulus thresholds less than 10 mA in intensity are worrisome and may indicate a pedicle breach, which may cause irritation or injury to the nerve tissue. However, stimulus thresholds can vary from person to person. Individuals with osteoporosis may have lower stimulus thresholds because of the poor bone density. Also, the current can take different paths through the tissue that depend on the surgical environment. A wet surgical field may result in current shunting, which could increase the threshold needed to activate the nerve roots. Current shunting is also an issue for minimally invasive surgeries in which the screws are inserted into the pedicles percutaneously. Here, the screws are inserted through the skin and soft tissue with the aid of fluoroscopy. When the pedicle screws are tested, the current is shunted to the surrounding tissue, which typically results in higher stimulus thresholds.

			""Lateral lumbar interbody fusions"". This procedure is considered minimally invasive. In contrast to posterior lumbar fusion, the incision for a lateral lumbar fusion approaches the lumbar spine from a far lateral approach that passes through the psoas muscles. The main advantages of this technique is that injury to the posterior spinal ligaments is avoided and that larger cages can be inserted for greater stability of the interbody device. However, there is a higher risk of injury to the lumbar plexus using this approach. While nerve injuries tend to be temporary, there is a risk for permanent motor and sensory deficits due to injury of the femoral nerve. IONM strategies for monitoring of LLIFs include a combination of EMG, transcranial MEPs and SSEPs of the saphenous nerve. The saphenous nerve is the largest terminal cutaneous branch of the femoral nerve.

	==Cervical spine surgery==		==Cervical spine surgery==