Spinal Stenosis - Versionshistorie

Admin: /* Classification */

2017-08-29T17:49:45Z

Classification

← Ældre version		Versionen fra 29. aug. 2017, 19:49
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	=Classification=		=Classification=
	Stenosis can be anatomically classified as central, lateral recess, and foraminal on the basis of the location of neural compression. With aging, central canal stenosis occurs as degenerative changes progress. As the axial height of the disc and facet joints decreases, the disc bulges into the spinal canal. The central canal is further narrowed by posterior impingement from enlarged facets and the hypertrophied ligamentum flavum (Fig. 62-4 ) . Hypertrophy of the soft tissues is responsible for 40% of spinal stenosis. With extension, the hypertrophied ligamentum buckles centrally into the canal and worsens the central stenosis. This explains why patients with stenosis typically report worsening of their symptoms in extension.		Stenosis can be anatomically classified as central, lateral recess, and foraminal on the basis of the location of neural compression. With aging, central canal stenosis occurs as degenerative changes progress. As the axial height of the disc and facet joints decreases, the disc bulges into the spinal canal. The central canal is further narrowed by posterior impingement from enlarged facets and the hypertrophied ligamentum flavum (Fig. 62-4). Hypertrophy of the soft tissues is responsible for 40% of spinal stenosis. With extension, the hypertrophied ligamentum buckles centrally into the canal and worsens the central stenosis. This explains why patients with stenosis typically report worsening of their symptoms in extension.

	[[Fil:F62-4.jpg]]		[[Fil:F62-4.jpg]]
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	Spinal stenosis can also be classified on the basis of the etiology, which can be congenital, acquired, or both. Congenital stenosis is present as a normal variant in the population and is part of certain conditions such as dwarfism. In these conditions, patients have short pedicles that are closer together than the normal lumbar spine. In congenital stenosis, few degenerative changes are sufficient to cause neural compression and symptoms. As one would expect, congenital stenosis becomes symptomatic much earlier in life and patients usually become symptomatic in the fourth decade. Acquired stenosis can be caused by trauma, neoplasms, and infection, along with other causes listed in Box 62-1.		Spinal stenosis can also be classified on the basis of the etiology, which can be congenital, acquired, or both. Congenital stenosis is present as a normal variant in the population and is part of certain conditions such as dwarfism. In these conditions, patients have short pedicles that are closer together than the normal lumbar spine. In congenital stenosis, few degenerative changes are sufficient to cause neural compression and symptoms. As one would expect, congenital stenosis becomes symptomatic much earlier in life and patients usually become symptomatic in the fourth decade. Acquired stenosis can be caused by trauma, neoplasms, and infection, along with other causes listed in Box 62-1.

	BOX 62-1 Classification of spinal stenosis		'''BOX 62-1 Classification of spinal stenosis'''
	#Congenital/developmental		#Congenital/developmental
	##Idiopathic		##Idiopathic

Admin: /* Electromyography, Nerve Condition Studies, and Somatosensory Evoked Potentials */

2017-08-29T17:42:32Z

Electromyography, Nerve Condition Studies, and Somatosensory Evoked Potentials

← Ældre version		Versionen fra 29. aug. 2017, 19:42
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	=Electromyography, Nerve Condition Studies, and Somatosensory Evoked Potentials=		=Electromyography, Nerve Condition Studies, and Somatosensory Evoked Potentials=
	Electromyography (EMG), nerve conduction studies (NCSs), and somatosensory evoked potentials (SSEPs) are not part of the routine workup of patients with spinal stenosis. EMG identifies the effect of nerve function through recording the electrical activity of muscle at rest and with stimulation. EMG identifies lower motor neuron dysfunction and does not evaluate any sensory dysfunction. Electromyographic changes have been documented in up to 80% of patients with spinal stenosis.~~84,91-94~~ EMG can be useful in differentiating chronic changes from active ongoing denervation. However, it should be kept in mind that there is a significant incidence of false-negative electromyograms in patients with spinal stenosis. This can be attributed to the fact that EMG does not measure sensory dysfunction and thus does not catch the more common abnormality in patients with neurogenic claudication. EMG also does not help differentiate symptomatic from asymptomatic patients.		Electromyography (EMG), nerve conduction studies (NCSs), and somatosensory evoked potentials (SSEPs) are not part of the routine workup of patients with spinal stenosis. EMG identifies the effect of nerve function through recording the electrical activity of muscle at rest and with stimulation. EMG identifies lower motor neuron dysfunction and does not evaluate any sensory dysfunction. Electromyographic changes have been documented in up to 80% of patients with spinal stenosis. EMG can be useful in differentiating chronic changes from active ongoing denervation. However, it should be kept in mind that there is a significant incidence of false-negative electromyograms in patients with spinal stenosis. This can be attributed to the fact that EMG does not measure sensory dysfunction and thus does not catch the more common abnormality in patients with neurogenic claudication. EMG also does not help differentiate symptomatic from asymptomatic patients.

	NCS measures the speed with which impulses travel down an axon. NCS is useful in differentiating changes that are occurring from neuropathy versus radiculopathy. SSEPs measure the electrical transmission of sensory stimulation starting from the peripheral nerves and going through the spinal cord and brain. A lesion in the peripheral nerve will prolong the latency response, whereas lesions of the root and cord will cause changes in the waveform. SSEP is more sensitive and specific compared with an EMG, although there continue to be false negatives and false positives.		NCS measures the speed with which impulses travel down an axon. NCS is useful in differentiating changes that are occurring from neuropathy versus radiculopathy. SSEPs measure the electrical transmission of sensory stimulation starting from the peripheral nerves and going through the spinal cord and brain. A lesion in the peripheral nerve will prolong the latency response, whereas lesions of the root and cord will cause changes in the waveform. SSEP is more sensitive and specific compared with an EMG, although there continue to be false negatives and false positives.

Admin: /* Magnetic Resonance Imaging */

2017-08-29T17:40:40Z

Magnetic Resonance Imaging

← Ældre version		Versionen fra 29. aug. 2017, 19:40
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	=Magnetic Resonance Imaging=		=Magnetic Resonance Imaging=
	MRI is the diagnostic modality of choice in patients with stenosis. It is noninvasive and provides images in axial, coronal, and sagittal planes. MRI offers details of both the bony and soft tissue anatomy. It provides improved visualization of the soft tissue elements of the spine (Figs. 62-9 and 62-10 g ) . The degree of compression of the neural elements and the offending pathology are both easily visualized. The central canal, lateral recess, and neural foramen can all be visualized along with the degree of stenosis that is present in each of these regions. Facet arthropathy, ligamentum hypertrophy, disc bulges or herniations, and other compressive pathology such as synovial cysts are easily identified on MRI (Fig. 62-11 i7 ) . Foraminal stenosis is best visualized on T1-weighted sagittal images in which the nerve root and dorsal root ganglion are contrasted with the surrounding fat.		MRI is the diagnostic modality of choice in patients with stenosis. It is noninvasive and provides images in axial, coronal, and sagittal planes. MRI offers details of both the bony and soft tissue anatomy. It provides improved visualization of the soft tissue elements of the spine (Figs. 62-9 and 62-10). The degree of compression of the neural elements and the offending pathology are both easily visualized. The central canal, lateral recess, and neural foramen can all be visualized along with the degree of stenosis that is present in each of these regions. Facet arthropathy, ligamentum hypertrophy, disc bulges or herniations, and other compressive pathology such as synovial cysts are easily identified on MRI (Fig. 62-11). Foraminal stenosis is best visualized on T1-weighted sagittal images in which the nerve root and dorsal root ganglion are contrasted with the surrounding fat.

	~~FIGURE 62~~-~~11 T2-weighted sagittal (A) and axial (B) magnetic resonance imaging of a patient with a right L5-S1 synovial cyst cau..~~.		[[Fil:F62-9.jpg]]

	~~Overall, the diagnostic accuracy of MRI is similar to that of the CT~~-~~myelogram and does not have the drawbacks of ionizing radiation and contrast injection in the CSF~~.72-75 The reliability of MRI interpretation has also been investigated, and there appears to be significant inter-reader variability in assessing some anatomic locations.76-79 The measurement of thecal sac area, as well as the ratings of the degree of central and foraminal stenosis, show good reliability.80 The reading of the degree of lateral recess stenosis, on the other hand, shows significant variability. Although some have noted correlation between the degree of stenosis and outcomes of treatments, others have not been able to identify any such relationship.81-84		[[Fil:F62-10.jpg]]

	It has been theorized that supine MRIs may understate the degree of stenosis because the patients may not be in the position of the worst compression during the study. Attempts have been made to demonstrate pathology in MRI scans that is obvious only under dynamic conditions.~~85-89~~ MRIs in flexion, extension, axial loading, and upright positions have been investigated without any conclusive evidence regarding their utility. It is unclear what the results of invasive treatments will be for those patients whose stenosis can only be detected under dynamic conditions. What the existing studies do point out is that the static images on the current MRIs should be supplemented with the dynamic information available from clinical presentation, as well as flexion and extension radiographs. One study noted that supine MRIs performed with the lumbar spine extended (by having the hips and knees extended) demonstrated more thecal sac compression than the images obtained in the flexed position.90 This suggests that position of the lower extremities during the MRI should be ascertained as a routine part of the patient's history.		[[Fil:F62-11.jpg]]

			Overall, the diagnostic accuracy of MRI is similar to that of the CT-myelogram and does not have the drawbacks of ionizing radiation and contrast injection in the CSF. The reliability of MRI interpretation has also been investigated, and there appears to be significant inter-reader variability in assessing some anatomic locations. The measurement of thecal sac area, as well as the ratings of the degree of central and foraminal stenosis, show good reliability. The reading of the degree of lateral recess stenosis, on the other hand, shows significant variability. Although some have noted correlation between the degree of stenosis and outcomes of treatments, others have not been able to identify any such relationship.

			It has been theorized that supine MRIs may understate the degree of stenosis because the patients may not be in the position of the worst compression during the study. Attempts have been made to demonstrate pathology in MRI scans that is obvious only under dynamic conditions. MRIs in flexion, extension, axial loading, and upright positions have been investigated without any conclusive evidence regarding their utility. It is unclear what the results of invasive treatments will be for those patients whose stenosis can only be detected under dynamic conditions. What the existing studies do point out is that the static images on the current MRIs should be supplemented with the dynamic information available from clinical presentation, as well as flexion and extension radiographs. One study noted that supine MRIs performed with the lumbar spine extended (by having the hips and knees extended) demonstrated more thecal sac compression than the images obtained in the flexed position. This suggests that position of the lower extremities during the MRI should be ascertained as a routine part of the patient's history.

	=Electromyography, Nerve Condition Studies, and Somatosensory Evoked Potentials=		=Electromyography, Nerve Condition Studies, and Somatosensory Evoked Potentials=

Admin: /* Computed Tomography with and Without Myelography */

2017-08-29T17:25:33Z

Computed Tomography with and Without Myelography

← Ældre version		Versionen fra 29. aug. 2017, 19:25
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	[[Fil:F62-6.jpg]]		[[Fil:F62-6.jpg]]

	Diagnostic utility of the CT scan can be improved by combining it with myelography.~~69'7°~~ The dye injected in the cerebrospinal fluid (CSF) during a myelogram provides good contrast between the thecal sac and the surrounding soft tissue and bony pathology. Preoperative complete contrast block on a CT-myelogram has been correlated with an improved surgical outcome.' The invasiveness of the myelogram and the radiation associated with the CT are the two biggest drawbacks of this diagnostic modality. Given these limitations, patients who are unable to have an MRI, who have scoliosis, or who have previous spinal instrumentation are the most likely to undergo this study (Figs. 62-7 and 62-8 g ). In cases where MRI findings are unclear, a CT or a CT-myelogram should be considered to gain further information about the pathology.		Diagnostic utility of the CT scan can be improved by combining it with myelography. The dye injected in the cerebrospinal fluid (CSF) during a myelogram provides good contrast between the thecal sac and the surrounding soft tissue and bony pathology. Preoperative complete contrast block on a CT-myelogram has been correlated with an improved surgical outcome.' The invasiveness of the myelogram and the radiation associated with the CT are the two biggest drawbacks of this diagnostic modality. Given these limitations, patients who are unable to have an MRI, who have scoliosis, or who have previous spinal instrumentation are the most likely to undergo this study (Figs. 62-7 and 62-8). In cases where MRI findings are unclear, a CT or a CT-myelogram should be considered to gain further information about the pathology.

	[[Fil:F62-7.jpg]]		[[Fil:F62-7.jpg]]

Admin: /* Computed Tomography with and Without Myelography */

2017-08-29T17:24:48Z

Computed Tomography with and Without Myelography

← Ældre version		Versionen fra 29. aug. 2017, 19:24
Linje 120:		Linje 120:
	Diagnostic utility of the CT scan can be improved by combining it with myelography.69'7° The dye injected in the cerebrospinal fluid (CSF) during a myelogram provides good contrast between the thecal sac and the surrounding soft tissue and bony pathology. Preoperative complete contrast block on a CT-myelogram has been correlated with an improved surgical outcome.' The invasiveness of the myelogram and the radiation associated with the CT are the two biggest drawbacks of this diagnostic modality. Given these limitations, patients who are unable to have an MRI, who have scoliosis, or who have previous spinal instrumentation are the most likely to undergo this study (Figs. 62-7 and 62-8 g ). In cases where MRI findings are unclear, a CT or a CT-myelogram should be considered to gain further information about the pathology.		Diagnostic utility of the CT scan can be improved by combining it with myelography.69'7° The dye injected in the cerebrospinal fluid (CSF) during a myelogram provides good contrast between the thecal sac and the surrounding soft tissue and bony pathology. Preoperative complete contrast block on a CT-myelogram has been correlated with an improved surgical outcome.' The invasiveness of the myelogram and the radiation associated with the CT are the two biggest drawbacks of this diagnostic modality. Given these limitations, patients who are unable to have an MRI, who have scoliosis, or who have previous spinal instrumentation are the most likely to undergo this study (Figs. 62-7 and 62-8 g ). In cases where MRI findings are unclear, a CT or a CT-myelogram should be considered to gain further information about the pathology.

	~~FIGURE 62~~-7 ~~g Myelogram of a patient with neurogenic claudication who had a history of a previous lumbar instrumented fusion. T..~~.		[[Fil:F62-7.jpg]]

	~~FIGURE 62~~-8 ~~Postmyelogram computed tomography through the adjacent-level stenosis of the patient in Figure 62-7 0~~.		[[Fil:F62-8.jpg]]

	=Magnetic Resonance Imaging=		=Magnetic Resonance Imaging=

Admin: /* Computed Tomography with and Without Myelography */

2017-08-28T19:55:55Z

Computed Tomography with and Without Myelography

← Ældre version		Versionen fra 28. aug. 2017, 21:55
Linje 116:		Linje 116:
	Prior to the common availability of magnetic resonance imaging (MRI), a computed tomography (CT) scan was the study of choice for visualizing pathologic anatomy in the axial plane. Because a significant portion of the stenosis comes from soft tissue pathology, visualization of the soft tissues is the top priority in axial imaging. A CT scan is a poor modality for detailed analysis of the soft tissue pathology (Fig. 62-6 g ). A meta-analysis demonstrated that the sensitivity of a CT scan in detecting spinal stenosis ranges from 70% to 100%.		Prior to the common availability of magnetic resonance imaging (MRI), a computed tomography (CT) scan was the study of choice for visualizing pathologic anatomy in the axial plane. Because a significant portion of the stenosis comes from soft tissue pathology, visualization of the soft tissues is the top priority in axial imaging. A CT scan is a poor modality for detailed analysis of the soft tissue pathology (Fig. 62-6 g ). A meta-analysis demonstrated that the sensitivity of a CT scan in detecting spinal stenosis ranges from 70% to 100%.

	~~FIGURE 62~~-6 ~~0 Soft tissue window of a computed tomography scan through the L4-5 level demonstrating stenos's. Please note the ..~~.		[[Fil:F62-6.jpg]]

	Diagnostic utility of the CT scan can be improved by combining it with myelography.69'7° The dye injected in the cerebrospinal fluid (CSF) during a myelogram provides good contrast between the thecal sac and the surrounding soft tissue and bony pathology. Preoperative complete contrast block on a CT-myelogram has been correlated with an improved surgical outcome.' The invasiveness of the myelogram and the radiation associated with the CT are the two biggest drawbacks of this diagnostic modality. Given these limitations, patients who are unable to have an MRI, who have scoliosis, or who have previous spinal instrumentation are the most likely to undergo this study (Figs. 62-7 and 62-8 g ). In cases where MRI findings are unclear, a CT or a CT-myelogram should be considered to gain further information about the pathology.		Diagnostic utility of the CT scan can be improved by combining it with myelography.69'7° The dye injected in the cerebrospinal fluid (CSF) during a myelogram provides good contrast between the thecal sac and the surrounding soft tissue and bony pathology. Preoperative complete contrast block on a CT-myelogram has been correlated with an improved surgical outcome.' The invasiveness of the myelogram and the radiation associated with the CT are the two biggest drawbacks of this diagnostic modality. Given these limitations, patients who are unable to have an MRI, who have scoliosis, or who have previous spinal instrumentation are the most likely to undergo this study (Figs. 62-7 and 62-8 g ). In cases where MRI findings are unclear, a CT or a CT-myelogram should be considered to gain further information about the pathology.

Admin: /* Computed Tomography with and Without Myelography */

2017-08-28T19:53:45Z

Computed Tomography with and Without Myelography

← Ældre version		Versionen fra 28. aug. 2017, 21:53
Linje 114:		Linje 114:

	==Computed Tomography with and Without Myelography==		==Computed Tomography with and Without Myelography==
	Prior to the common availability of magnetic resonance imaging (MRI), a computed tomography (CT) scan was the study of choice for visualizing pathologic anatomy in the axial plane. Because a significant portion of the stenosis comes from soft tissue pathology, visualization of the soft tissues is the top priority in axial imaging. A CT scan is a poor modality for detailed analysis of the soft tissue pathology (Fig. 62-6 g ). A meta-analysis demonstrated that the sensitivity of a CT scan in detecting spinal stenosis ranges from ~~700/0~~ to 100%.60		Prior to the common availability of magnetic resonance imaging (MRI), a computed tomography (CT) scan was the study of choice for visualizing pathologic anatomy in the axial plane. Because a significant portion of the stenosis comes from soft tissue pathology, visualization of the soft tissues is the top priority in axial imaging. A CT scan is a poor modality for detailed analysis of the soft tissue pathology (Fig. 62-6 g ). A meta-analysis demonstrated that the sensitivity of a CT scan in detecting spinal stenosis ranges from 70% to 100%.

	FIGURE 62-6 0 Soft tissue window of a computed tomography scan through the L4-5 level demonstrating stenos's. Please note the ...		FIGURE 62-6 0 Soft tissue window of a computed tomography scan through the L4-5 level demonstrating stenos's. Please note the ...
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	FIGURE 62-7 g Myelogram of a patient with neurogenic claudication who had a history of a previous lumbar instrumented fusion. T...		FIGURE 62-7 g Myelogram of a patient with neurogenic claudication who had a history of a previous lumbar instrumented fusion. T...

	FIGURE 62-8 Postmyelogram computed tomography through the adjacent-level stenosis of the patient in Figure 62-7 0.		FIGURE 62-8 Postmyelogram computed tomography through the adjacent-level stenosis of the patient in Figure 62-7 0.

	=Magnetic Resonance Imaging=		=Magnetic Resonance Imaging=

Admin: /* Radiography */

2017-08-28T19:53:07Z

Radiography

← Ældre version		Versionen fra 28. aug. 2017, 21:53
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	The diagnostic testing of patients with spinal stenosis often starts with plain radiographs. In addition to the anteroposterior and lateral radiographs, flexion and extension lateral views should be considered. Most patients suspected of stenosis are elderly and thus likely demonstrate a variety of spondylotic changes on the radiographs. Particular attention should be paid to diagnosing scoliosis and spondylolisthesis in addition to any dynamic instability that can be detected on the flexion-extension views. If scoliosis is noted, long cassette scoliosis films would be helpful in evaluating the full extent of the deformity in both the coronal and sagittal planes. Narrowing of the neural foramen and inferred narrowing of the spinal canal from the location and extent of degenerated structures should be evaluated. Ossification of ligamentous structures, ankylosis of the spine, erosion of the disc space, or any abnormal appearance of the bony structures should be assessed (Fig. 62-5 0 ). It should be kept in mind that even severe degenerative changes can be seen in asymptomatic patients.		The diagnostic testing of patients with spinal stenosis often starts with plain radiographs. In addition to the anteroposterior and lateral radiographs, flexion and extension lateral views should be considered. Most patients suspected of stenosis are elderly and thus likely demonstrate a variety of spondylotic changes on the radiographs. Particular attention should be paid to diagnosing scoliosis and spondylolisthesis in addition to any dynamic instability that can be detected on the flexion-extension views. If scoliosis is noted, long cassette scoliosis films would be helpful in evaluating the full extent of the deformity in both the coronal and sagittal planes. Narrowing of the neural foramen and inferred narrowing of the spinal canal from the location and extent of degenerated structures should be evaluated. Ossification of ligamentous structures, ankylosis of the spine, erosion of the disc space, or any abnormal appearance of the bony structures should be assessed (Fig. 62-5 0 ). It should be kept in mind that even severe degenerative changes can be seen in asymptomatic patients.

	~~FIGURE 62~~-5 ~~E1 Anteroposterior (AP) (A) and lateral (B) radiograph of a patient with progressively worsening right lumbar radiculop..~~.		[[Fil:F62-5.jpg]]

	==Computed Tomography with and Without Myelography==		==Computed Tomography with and Without Myelography==

Admin: /* Classification */

2017-08-28T19:49:56Z

Classification

← Ældre version		Versionen fra 28. aug. 2017, 21:49
Linje 36:		Linje 36:
	Stenosis can be anatomically classified as central, lateral recess, and foraminal on the basis of the location of neural compression. With aging, central canal stenosis occurs as degenerative changes progress. As the axial height of the disc and facet joints decreases, the disc bulges into the spinal canal. The central canal is further narrowed by posterior impingement from enlarged facets and the hypertrophied ligamentum flavum (Fig. 62-4 ) . Hypertrophy of the soft tissues is responsible for 40% of spinal stenosis. With extension, the hypertrophied ligamentum buckles centrally into the canal and worsens the central stenosis. This explains why patients with stenosis typically report worsening of their symptoms in extension.		Stenosis can be anatomically classified as central, lateral recess, and foraminal on the basis of the location of neural compression. With aging, central canal stenosis occurs as degenerative changes progress. As the axial height of the disc and facet joints decreases, the disc bulges into the spinal canal. The central canal is further narrowed by posterior impingement from enlarged facets and the hypertrophied ligamentum flavum (Fig. 62-4 ) . Hypertrophy of the soft tissues is responsible for 40% of spinal stenosis. With extension, the hypertrophied ligamentum buckles centrally into the canal and worsens the central stenosis. This explains why patients with stenosis typically report worsening of their symptoms in extension.

	~~FIGURE 62~~-4 ~~Axial view cross section at the L4-5 disc level showing advanced degenerative changes. Cauda equina (CE) compress..~~.		[[Fil:F62-4.jpg]]

	Lateral recess stenosis typically results from posterior disc protrusion in combination with some superior articular facet hypertrophy. Lateral recess stenosis can present with lumbar radiculopathy, and incidence of lateral recess stenosis ranges from 8% to 11%. These patients present with pain or neurologic symptoms in a dermatomal distribution on the basis of the nerve that is compressed in the lateral recess.		Lateral recess stenosis typically results from posterior disc protrusion in combination with some superior articular facet hypertrophy. Lateral recess stenosis can present with lumbar radiculopathy, and incidence of lateral recess stenosis ranges from 8% to 11%. These patients present with pain or neurologic symptoms in a dermatomal distribution on the basis of the nerve that is compressed in the lateral recess.
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	##Traumatic		##Traumatic
	#Combined		#Combined
	Any combination of congenital/developmental or acquired stenosis		Any combination of congenital/developmental or acquired stenosis

	=Deformity and Instability=		=Deformity and Instability=

Admin: /* Intervertebral Foramen */

2017-08-28T19:40:23Z

Intervertebral Foramen

← Ældre version		Versionen fra 28. aug. 2017, 21:40
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	The anterior boundary of the intervertebral foramen is made up of the posterior wall of the vertebral body and the disc. The posterior boundary is made up of the lateral aspect of the facet joint and the ligamentum flavum. Superior and inferior boundaries are formed by the pedicles of the vertebral bodies corresponding to that segment. The foramen is typically larger than the ganglion and the nerve that it contains. The additional space is occupied by fat and loose areolar tissue that can accommodate for motion. With degeneration, hypertrophy of the facets can cause posterior compression of the neural elements (Fig. 62-2) . Anterior compression of the neural elements usually arises from endplate osteophytes or foraminal disc herniations. Decrease in disc height with degeneration can cause a decrease in the foraminal height and neural compression. This type of vertical or up-down foraminal stenosis is important to recognize because a posterior decompression alone may not significantly improve the vertical compression and may result in persistent symptoms after surgery.		The anterior boundary of the intervertebral foramen is made up of the posterior wall of the vertebral body and the disc. The posterior boundary is made up of the lateral aspect of the facet joint and the ligamentum flavum. Superior and inferior boundaries are formed by the pedicles of the vertebral bodies corresponding to that segment. The foramen is typically larger than the ganglion and the nerve that it contains. The additional space is occupied by fat and loose areolar tissue that can accommodate for motion. With degeneration, hypertrophy of the facets can cause posterior compression of the neural elements (Fig. 62-2) . Anterior compression of the neural elements usually arises from endplate osteophytes or foraminal disc herniations. Decrease in disc height with degeneration can cause a decrease in the foraminal height and neural compression. This type of vertical or up-down foraminal stenosis is important to recognize because a posterior decompression alone may not significantly improve the vertical compression and may result in persistent symptoms after surgery.

	~~FIGURE 62-2 Sagittal cross section demonstrating disc desiccation (D), endplate sclerosis (S), osteophyte formation (0), hypertro.~~
	[[Fil:F62-2.jpg]]		[[Fil:F62-2.jpg]]