6. Spine MCQs

This patient has developed a C5 palsy, a well-recognized complication of cervical decompression, especially posterior laminectomy and fusion. It occurs in up to 5-10% of cases. The prevailing theory is that the decompression allows the spinal cord to drift posteriorly (the 'bowstring' effect), causing traction and tethering of the relatively short C5 nerve roots. It presents as deltoid and/or biceps weakness, typically without sensory loss or long-tract signs, and can occur immediately or a few days postoperatively.

Symptomatic anterior atlantoaxial subluxation with neurological signs (myelopathy) and a posterior atlantodental interval (PADI) of less than 14 mm is a strong indication for surgical stabilization to prevent catastrophic spinal cord injury. For reducible AAS without vertical subluxation (basilar invagination) or lateral mass destruction, a posterior C1-C2 instrumented fusion is the standard treatment. Odontoid screw fixation is used for acute type II odontoid fractures, not RA. Occipitocervical fusion is reserved for cases with vertical subluxation/basilar invagination.

The clinical presentation is classic for a C6 radiculopathy. The C6 nerve root innervates the extensor carpi radialis longus and brevis (wrist extension) and the biceps and brachioradialis muscles (elbow flexion/pronation). The brachioradialis reflex is mediated by C6. Sensory distribution of C6 covers the lateral forearm, thumb, and index finger. C5 compression would present with deltoid/biceps weakness and a diminished biceps reflex. C7 compression causes triceps and wrist flexion weakness, a diminished triceps reflex, and middle finger numbness.

In the setting of a postoperative cerebrospinal fluid (CSF) leak following an intraoperative dural tear that was primarily repaired, initial management of a small, uninfected wound leak often includes over-sewing the wound edge, strict flat bed rest, and avoidance of increased intrathecal pressure (Valsalva). If conservative measures fail, a subarachnoid drain or re-operation may be considered. Placing a wound VAC is strictly contraindicated as the negative pressure will continuously pull CSF, preventing closure of the dural defect.

The patient has classic signs of degenerative cervical myelopathy (DCM), including hand clumsiness, gait instability, and upper motor neuron signs (Hoffmann sign, hyperreflexia). Imaging confirming stenosis with cord signal change corresponds to his clinical presentation. The most appropriate treatment for progressive or symptomatic DCM is surgical decompression (via an anterior, posterior, or combined approach) to halt the progression of neurologic decline. Nonoperative treatment is inadequate for progressive myelopathy.

The inverted brachioradialis reflex occurs when tapping the brachioradialis tendon produces finger flexion (or absent radial reflex) rather than the normal response. It is highly specific for cervical myelopathy at the C5-C6 level. The Hoffmann sign, while highly sensitive for upper motor neuron pathology, lacks specificity and can be observed in up to 3% of asymptomatic individuals.

In the setting of cervical spondylotic myelopathy, T1-weighted hypointense signal within the spinal cord (often referred to as a 'black cord') indicates cystic myelomalacia and necrosis. This finding represents permanent structural damage and correlates strongly with poor postoperative neurologic recovery. While T2-weighted hyperintensity is a sensitive marker for cord edema and gliosis, it is not as highly specific for irreversible injury as T1 hypointensity.

Circumferential fusion is the preferred choice for patients undergoing revision surgery following failed posterolateral fusions for isthmic spondylolisthesis as well as for those patients having primary surgery for high-grade isthmic spondylolisthesis.

Central cord syndrome is characterized by greater neurologic involvement of the upper extremities than the lower extremities. This is typically seen in older patients with cervical spondylosis without associated bony injury or joint subluxation. The prognosis for recovery is fair. Patients with Brown-Sequard syndrome have an ipsilateral motor deficit and contralateral loss of pain and temperature. Prognosis for recovery depends on the mechanism of injury, which is often of a penetrating nature. Anterior cord syndrome results from anterior compression such as occurs with a burst or teardrop fracture of the vertebral body; patients have bilateral motor loss, pain, and temperature loss with preservation of proprioception and vibratory sensation (posterior column function). The prognosis for recovery is generally poor. Posterior cord syndrome is rare and is associated with loss of posterior column function (proprioception and vibration). Northrup BE: Evaluation and early treatment of acute injuries to the spine and spinal cord, in Clark CR (ed): The Cervical Spine, ed 3. Philadelphia, PA, Lippincott-Raven, 1998, pp 541-549.

In a study of 427 patients undergoing cervical spine surgery, 12 patients demonstrated substantial or complete loss of amplitude of the tceMEPs. Ten of those patients had complete reversal of the loss following prompt intraoperative intervention. SSEP monitoring failed to identify any changes in one of the two patients that awoke with a new motor deficit. SSEP changes lagged behind the tceMEP changes in patients in which major changes were detected by both modalities. TceMEP monitoring was 100% sensitive and 100% specific. SSEP monitoring was only 25% sensitive and 100% specific.

Surgery is indicated for congenital kyphosis once the deformity reaches a certain size or if significant progression is documented. In a young patient with a relatively small deformity, the treatment of choice is isolated in situ posterior fusion and postoperative immobilization. If an adequate posterior fusion can be obtained, an epiphyseodesis effect can be generated, allowing the remaining anterior growth to cause some correction. Because there is no evidence of neurologic compression and the deformity is less than 50 degrees, anterior surgery is not indicated. There is no role for bracing in the management of congenital kyphosis. Winter RB: Congenital Deformities of the Spine. New York, NY, Thieme-Stratton, 1983, pp 229-261.

Although the spinal canal has been penetrated, the lateral masses are intact bilaterally with only partial destruction of the vertebral body and penetration of the lamina on one side, thus the cervical spine is not unstable and surgical stabilization is not indicated. Dural repair is not indicated since there is no external cerebrospinal fluid leakage. Surgical treatment should be based on the need to treat extraspinal pathology only. Bono CM, Heary RF: Gunshot wounds to the spine. Spine J 2004;4:230-240.

The patient has a displaced burst fracture. Fusion with instrumentation has shown better results than casting alone. Posterior fusion with instrumentation, with sagittal plane correction, yields the best results. Decompression occurs indirectly with correction of the kyphosis. Anterior decompression is unnecessary. Lalonde F, Letts M, Yang JP, et al: An analysis of burst fractures of the spine in adolescents. Am J Orthop 2001;30:115-120. Clark P, Letts M: Trauma to the thoracic and lumbar spine in the adolescent. Can J Surg 2001;44:337-345.

Because hydrosyringomyelia, with or without an Arnold-Chiari malformation, is now being recognized as the etiology of many infantile and juvenile idiopathic scolioses, management should consist of a neurosurgical consultation. Observation with follow-up radiographs is not an option in curves of this magnitude. A technitium Tc 99m bone scan is unnecessary because the etiology of the curve has been identified. Although spinal fusion may be needed in the future, it should not be undertaken before the neurosurgical problem has been addressed. Zadeh HG, Sakka SA, Powell MP, Mehta MH: Absent superficial abdominal reflexes in children with scoliosis: An early indicator of syringomyelia. J Bone Joint Surg Br 1995;77:762-767. Schwend RM, Hennrikus W, Hall JE, Emans JB: Childhood scoliosis: Clinical indications for magnetic resonance imaging. J Bone Joint Surg Am 1995;77:46-53.

Based on the radiographic findings of marked disruption of the posterior ligamentous complex with a relatively small anterior bony fracture, the patient has a classic Chance-type ligamentous flexion-distraction injury. The pathology is mostly in soft tissues with limited healing potential. The treatment of choice is posterior reconstruction of the tension band with a short segment fusion with instrumentation. Casting or bracing may result in a painful kyphosis with ligamentous insufficiency. The anterior bony column is mostly intact, so anterior reconstruction is not necessary. Carl AL: Adult spine trauma, in DeWald RL (ed): Spinal Deformities: A Comprehensive Text. New York, NY, Thieme, 2003, pp 406-423.

The patient has a burst fracture with probable unilateral entrapment of the cauda equina within the elements of the fractured lamina. A dural tear is likely in this scenario as well. It is recommended that this type of burst fracture be treated surgically with laminectomy, freeing of the entrapped nerve roots, and dural repair followed by stabilization of the fracture by either a posterior or combined approach. The degree of kyphosis and the extent of anterior canal compromise does not warrant corpectomy in this patient. Therefore, after completing the laminectomy and dural repair, posterior fusion and instrumentation should be sufficient to stabilize the fracture. Cammisa FP Jr, Eismont FJ, Green BA: Dural laceration occurring with burst fractures and associated laminar fractures. J Bone Joint Surg Am 1989;71:1044-1052.

This is a classic bilateral facet dislocation. When there is no evidence of a disk herniation, treatment should include careful skeletal traction, closed reduction, and posterior fusion. There is no role for anterior procedures. These fractures are unstable and require surgical intervention. Herkowitz HN, Garfin SR, Eismont FJ: Rothman-Simone The Spine, ed 5. Philadelphia, PA, Saunders Elsevier, 2006, pp 1120-1128.

The string passes under the ligamentum flavum as it runs from the posterior aspect of the vertebra above to the inferior aspect of the vertebra below in the sagittal midline. This is an important structure in diskectomy and in posterior approaches to the thoracolumbar spine and neural elements. It is rarely visualized in its entirety because typical exposures provide only a limited view.

The L5 nerve root lies directly over the superior and anterior alae. If the screw is directed approximately 20 degrees laterally and bicortical purchase is achieved, there is the risk of injuring the L5 nerve root. If the screw is directed medially into the body of S1, there is little risk of injury. The same root is at risk during placement of an iliosacral screw. Ebraheim NA, et al: Lumbosacral nerve and dorsal screw placement. Orthopedics 2000;23:245-247. Ebraheim NA, Mermer M, Xu R, Yeasting RA: Radiological evaluation of S1 dorsal screw placement. J Spinal Disord 1996;9:527-535.

The patient has chronic neck pain that is affecting his career as a professional soccer player. Although he had signs and symptoms of a right C6 radiculopathy, neck pain is his only current symptom. Therefore, procedures to address the relief of radiculopathy (keyhole foraminotomy and transforaminal epidural steroid injection) are likely to be ineffective. Although Watkins and others have described continuing nonsurgical management for symptomatic herniated disks and return to play only when asymptomatic, the patient has not found relief with these modalities. A single-level cervical fusion (either postoperative or congenital) generally is not considered a contraindication for return to play in collision or contact sports. Therefore, anterior cervical fusion at C5-6 offers the best long-term option for return to play. Watkins RG: Cervical spine injuries in athletes, in Clark CR (ed): The Cervical Spine, ed 3. Philadelphia, PA, Lippincott Raven, 1998, pp 373-386. Watkins RG: Neck injuries in football players. Clin Sports Med 1986;5:215-246. Morganti C, Sweeney CA, Albanese SA, et al: Return to play after cervical spine injury. Spine 2001;26:1131-1136.