1. Answer A. (MN-113) Disk herniations in the thoracic spine are far less common than in the lumbar or cervical spine. The stabilizing force of the rib cage limits motion in thoracic spine and therefore disk herniations. Moreover, in contrast to the cervical and lumbar spine, the thoracic spine is designed for stability rather than motion.

2. Answer D. (MN-113) The symptoms describe motor and sensory dysfunction with the S1 nerve root (Table 15.2.1). The S1 root is typically compressed from disk disease in the L5-S1 disk space. In the lumbar spine, most disc degeneration occurs at the L4-L5 and L5-S1 levels. More than 80% of lumbar disc syndromes affect the L5 or S1 nerve.

3. Answer C. (MN-113) Paramedian lumbar disc herniations generally impinge on nerve roots that exit the spinal canal, at a level just below the site of disc herniation. For example, a paramedian herniated disc at the L4-L5 level compresses the L5 nerve root, which exits the spinal canal through the L5-S1 intervertebral foramen.

4. Answer E. (MN-113) The symptoms describe motor and sensory dysfunction with the C8 nerve root, which courses through the C7-T1 intervertebral foramen (Table 15.2.1). This patient is at risk of cervical myelopathy. Cervical stenosis from degenerative disc disease can lead to disabling loss of neurologic function without significant pain and/or focal weakness. Important elements of the patient history and physical include issues with balance and/or fine motor control using their hands, as subtle deficits can imply significant and progressive pathology.

5. Answer B. (MN-113) The patient has a disk herniation at the level of C4-5 impacting his right C5 nerve root, which results in deltoid and biceps weakness. Pain and sensory loss may be found over the shoulder and anterior arm along with diminished biceps reflex. Disk herniation at the level of C5-6 impinges the C6 root causing pain and sensory loss in the radial forearm and biceps weakness (without deltoid weakness); C6-7 disk herniation causes C7 impingement with pain and sensory loss in the thumb and middle fingers with triceps and writs extensor weakness; and C7-T1 disk herniation impinges the C8 root and causes pain and sensory loss in the index, fourth, and fifth fingers with weakness in intrinsic hand muscles. C3-C4 disk herniation impinges the C4 root and may cause vague symptoms of pain in the neck and numbness in a C4 dermatomal distribution about the neck but not typically with obvious weakness (Table 15.2.1).

6. Answer B. (MN-114) This patient presents with clinical symptoms suggestive of cervical spondylotic myelopathy (CSM). Imaging studies are required to confirm all diagnoses of CSM. and the gold standard for this is an MRI of the cervical spine. Plain radiographs may offer information about the spinal alignment and may be needed for preoperative decision making but do not provide the detail seen in MRI. CT myelography is a reasonable, although invasive, alternative for patients who are unable to undergo an MRI. Noncontrast CT scans may offer additional information to that obtained from an MRI such as the presence of calcified posteriorly longitudinal ligaments or intervertebral discs, but they are not the study of choice. EMG and NCS would not demonstrate cervical stenosis but may identify cervical radiculopathy, which commonly co-occurs with cervical stenosis due to related structural changes in the spine. See Table 15.6.1 for clinical diagnostic features of cervical myelopathy and Figure 15.6.1 for a demonstration of changes typical of cervical stenosis.