6. Spine MCQs

DISCUSSION: The patient has a single-level deficit by clinical examination but an adjacent level that may be pathologic. Hilibrand and associates, in a review of 374 patients with myeloradiculopathy treated with single-level or multilevel anterior cervical diskectomy and fusion, showed that 25% of patients had an occurrence of new radiculopathy or myelopathy at an adjacent level within 10 years after surgery. Reoperation rates were highest in those patients where the adjacent nonfused segment was C5-6 or C6-7. Those patients who had multilevel fusions had a lower incidence of adjacent segment disease. The authors recommended incorporating an adjacent level in the initial procedure in patients with myelopathy or radiculopathy when significant disease was noted. Posterior keyhole foraminotomy is an excellent procedure for single-level radiculopathy but is not effective in relieving myelopathy. Anterior cervical diskectomy without fusion has an increased incidence of hypermobility and neck pain on long-term follow-up. In a later review, these authors reported improved fusion rates and better clinical outcomes with the use of strut fusions instead of multilevel interbody grafts. REFERENCES: Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH: Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am 1999;81:519-528. Henderson CM, Hennessy RG, Shuey HM Jr, Shackelford EG: Posterior-lateral foraminotomy as an exclusive operative technique for cervical radiculopathy: A review of 846 consecutively operated cases. Neurosurgery 1983;13:504-512. Hilibrand AS, Fye MA, Emery SE, Palumbo MA, Bohlman HH: Impact of smoking on the outcome of anterior cervical arthrodesis with interbody or strut grafting. J Bone Joint Surg Am 2001;83:668-673.

DISCUSSION: The projectile entered the left shoulder and traveled to the right neck; therefore, a high incidence of suspicion must be directed to the airway, great vessels of the neck, and contents of the mediastinum. Immediate assessment of airway, breathing, and circulation takes priority, followed by examination of the neurologic status and other systems, as determined by the examination findings. REFERENCES: Subcommittee on ATLS of the American College of Surgeons Committee on Trauma 1993-1997, Spine and Spinal Cord Trauma; Advanced Trauma Life Support Student Manual, ed 6, 1997. International Standards for Neurological and Functional Classification of Spinal Cord Injury. American Spinal Injury Association and International Medical Society of Paraplegia (ASIA/IMSOP).

DISCUSSION: During the direct lateral approach, interbody fusion devices are inserted through a lateral window in the psoas muscle. To accomplish this, dilators and retractors are positioned at the posterior half of the disk space, and it must be noted that the lumbosacral plexus lies within the psoas muscle between the transverse process and vertebral body and departs distally at the medial edge of the psoas. Consequently, lateral interbody fusion poses risk for injury to the lumbosacral plexus. A cadaveric study demonstrated that the lumbosacral plexus progressively migrates from dorsal to ventral in the lumbar spine. Therefore, the plexus is most likely to be injured during an L4-L5 fusion because at this level the lumbosacral plexus is closest to the location at which dilators and retractors are placed. A 2013 retrospective study by Le and associates followed 71 patients who underwent minimally invasive fusion via a lateral interbody approach. In this study, 54.9% (39/71) had immediate postsurgical ipsilateral iliopsoas or quadriceps weakness. Of these patients, the majority had resolution by 3 months (92.3%), and all had complete resolution by 2 years.

The ligamenta flava (singular, ligamentum flavum, Latin for yellow ligament) are ligaments that connect the laminae of adjacent vertebra, all the way from the axis to the first segment of the sacrum. In T2-weighted sequencing, ligamentous structures possess a low signal intensity. The ligamentum in this patient is markedly thickened, resulting in severe spinal stenosis. The epidural space lies ventral and medial to the ligamentum flavum and should possess a high signal intensity secondary to the presence of cerebrospinal fluid. However, in the case of high-grade stenosis, there may be little if any cerebrospinal fluid present, making the epidural space and central canal difficult to identify. A lumbar synovial cyst should also have high signal intensity because of the presence of synovial fluid.(SBQ12SP.14) A 36-year-old male presents with acute onset of right buttock and leg pain following lifting a heavy object. On physical exam he has weakness to knee extension, numbness over the medial malleolus, and a decreased patellar reflex. Which of the following would most likely explain this clinical presentation.ReviewTopicLumbar arachnoiditisL4/L5 paracentral disc herniationL3/L4 far lateral (foraminal) disc herniationL4/L5 far lateral (foraminal) disc herniationL5/S1 far lateral (foraminal) disc herniationThe clinical presentation is consistent with a L4 radiculopathy. A L4/L5 far lateral (foraminal) disc herniation would compress the exiting root (L4) and cause these symptoms.The location of a prolapsed lumbar disc determines its symptoms. Central disc herniations may give rise to back pain or cauda equina syndrome. Paracentral disc herniations (90-95% of cases) affect the traversing nerve root. Far lateral disc herniations (5-10%) affect the exiting nerve root.Gregory et al. summarize physical signs in lumbar disc herniation. They state that the straight-leg-raise is the most sensitive (73-98% sensitive) test and the crossed straight-leg-raise is the most specific (88-98% specific) test for lumbar disc herniation. Other specific tests include weak ankle dorsiflexion (89% specific), absent ankle reflex (89% specific), and calf wasting (94% specific, but a late finding).Illustration A shows how a paracentral L4/L5 disc herniation affects the traversing L5 root, but a far lateral L4/L5 disc herniation affects the L4 root. Illustration B shows the dermatomal distribution of pain with root involvement from L3 to S1.Incorrect Answers:

DISCUSSION: To mobilize the common iliac vessels across the midline, the iliolumbar vein must be ligated. It has a short trunk and can be torn if mobilization is attempted without ligation. It is the only branch off the common iliacs (there are no arterial branches) prior to the terminal branches, the internal (hypogastric) and external iliacs. The middle sacral vessels run distally from the axilla of the bifurcation and are a factor when accessing the L5-S1 disk. REFERENCES: Baker JK, Reardon PR, Reardon MJ, et al: Vascular injury in anterior lumbar surgery. Spine 1993;18:2227-2230. Lewis WH: Gray’s Anatomy of the Human Body: The Veins of the Lower Extremity, Abdomen, and Pelvis, ed 20. Philadelphia, PA, Lea & Febiger, 2000.

DISCUSSION: 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.

DISCUSSION: Complications frequently occur following treatment for spinal disorders. Wound infections are among the most commonly encountered complications following any surgical intervention; however, their incidence after routine spine surgery is generally low. Postsurgical wound infection is common following large tumor resection such as sacrectomy performed for treatment of chordomas.

The CT scan reveals a right-sided lateral disk protrusion at L3-4 that has been symptomatic for more than 4 months despite appropriate nonsurgical management. Relative surgical indications include persistent radiculopathy despite an adequate trial of nonsurgical management, recurrent episodes of sciatica, persistent motor deficit with tension signs and pain, and pseudoclaudication caused by underlying stenosis. Whereas studies have shown improvement in patients with sciatica from a lumbar disk herniation treated either nonsurgically or surgically, those undergoing surgical treatment had an overall greater improvement of symptoms.

The clinical presentation is consistent with a paracentral disc herniation at L4/5 that has failed nonoperative treatment and continues to limit is his activities of daily living. A laminotomy and discectomy (microdisckectomy) with a midline approach would be the next most appropriate treatment.For lumbar disc herniation, the first line of treatment is rest, physical therapy and oral medications (NSAIDs, gabapentin, steroids). The second line of treatment is selective nerve root corticosteroid injections. The last line in treatment is laminotomy and discectomy.Pearson et al. determined which individuals (as opposed to groups) in the SPORT (Spine Patients Outcomes Research Trial) would benefit from surgery. They found that disc herniation patients improved more with surgery than without.Lurie et al. reviewed the 8 year outcomes of the SPORT. In patients with HNP on imaging and leg symptoms persisting for at least 6 weeks, surgery was superior to nonoperative treatment in relieving symptoms and improving function.Figures A and B are sagittal and axial T2-weighted MRI images showing a large L4/L5 herniated disc causing neural foramina narrowing and impinging on the right L5 root.Incorrect Answers:

DISCUSSION: The Short-form 36 is an excellent tool for measuring the patient’s perception of treatment outcome because it is a patient-generated, validated assessment of physical, social, and role function, emotional and mental health, energy/fatigue, pain, health perception, and health change. The Nurick criteria is an evaluation of physical function with gradations of ambulation and daily function. The Japanese Orthopaedic Association score gives points for function in activities of daily living but does not assess perception of general health. The Neck Disability Index assesses the impact of neck pain on daily life, and the Odom criteria are the surgeon’s evaluations of degree of radicular pain and deficit.

DISCUSSION: When markedly diminished space available for the cord (demonstrated by a posterior atlantoaxial interval of less than 10 mm) is seen, there is a poor prognosis for recovery (25% of Ranawat class IIIb patients) following surgery. A posterior atlantoaxial interval of 14 mm or less is a predictor of increased risk of paralysis, but patients with an interval between 10 mm and 14 mm have a greater chance of recovery. Space available for the cord that is at least 14 mm is not associated with an increased risk of neurologic deficit.

Congenital scoliosis has a high association with VACTERL anomalies and intraspinal anomalies (such as tethered cord, diastematomyelia, syringomyelia). Approximately 20-40% of patients with congenital scoliosis have an associated intraspinal anomaly, mandating an MRI of the entire neuroaxis to rule out these conditions before any surgical intervention or bracing.

Adults with achondroplasia frequently require surgery for symptomatic lumbar spinal stenosis. This is caused by congenitally short pedicles, thickened lamina, and a narrowing interpedicular distance in the lower lumbar spine.

Posterior atlantoaxial arthrodesis predictably relieves pain associated with arthrosis of the atlantoaxial joints. Typically, these patients have pain at the base of the occiput and in the most cephalad portion of the posterior aspect of the neck. Associated headache is common and often severe. Pain is aggravated by rotation but usually not by flexion and extension. Diagnostic blocks of the C1-C2 joint and the greater occipital nerve may be helpful to confirm the diagnosis preoperatively.

DISCUSSION: Spinal stabilization is the treatment of choice in patients with severe scoliosis who have progressive positioning, sitting balance, and/or hygiene problems despite maximal nonsurgical management. Pelvic rigidity and marked frontal plane deformity necessitate anterior and posterior procedures so as to maximize correction and fusion.

DISCUSSION: Although obesity can make brace or halo wear difficult, it has not been associated with an increased risk for nonunion.

The MRI scan shows a C7 burst fracture. A CT scan of the cervical spine will allow for optimal evaluation of this C7 burst fracture. Specifically, it will provide additional osseous detail and will assist with the detection of additional fractures, including those of the posterior elements. Additional CT imaging of the thoracic and lumbar spine is required to rule out concommitant injuries (which may be present in 10% to 15% of patients). Anteroposterior and lateral cervical spine radiographs would be a good option for further evaluation but are not included in the available choices here. Cervical spine flexion and extension radiographs should not be obtained in a patient who is known to have a relatively unstable spine and a neurologic deficit. Electromyography and nerve conduction velocity studies are best used to evaluate for cervical radiculopathy secondary to degenerative abnormalities and are usually not indicated in the acute trauma setting.

Adult patients with isthmic spondylolisthesis most commonly have neurologic symptoms due to foraminal stenosis at the level of the spondylolisthesis. In this scenario, the patient is most likely to have weakness of the L5 myotome, which would cause weakness of the extensor hallucis longus.

The images show enhancement about the left S1 root, a finding that is most consistent with perineural (epidural) fibrosis. The root itself does not enhance. A disk herniation does not enhance with gadolinium.

DISCUSSION: This patient has congenital and acquired spinal stenosis with multilevel disk protrusions that have both chronic (calcified) and acute components, resulting in multilevel cauda equina compression and acute cauda equina syndrome of more than 48 hours duration. Most studies indicate that patients who undergo decompression within 48 hours of symptom onset have a better prognosis for neurologic recovery than those who undergo decompression after 48 hours. Among patients with urinary incontinence, 1 study indicated that 43% remained incontinent at follow-up visits, but this study included a mix of early and late surgical patients. In another series of 44 patients with acute cauda equina syndrome, chronic bowel and bladder dysfunction were issues for 63% of those for whom surgery was delayed for more than 48 hours after symptom onset.