6. Spine MCQs

The primary change that takes place in the aging spine is degeneration of the lumbar disks and loss of the overall lumbar lordosis. This also may be associated with osteopenic-related compression fractures. With these changes, the sagittal vertical line moves anteriorly relative to the sacrum; cervical scoliosis is uncommon and not part of the normal aging process. Overall kyphosis in the thoracic spine gradually increases, but the coronal balance remains essentially the same unless scoliosis develops.

Infantile idiopathic scoliosis occurs more commonly in boys, with a 3 to 1 male to female ratio. Neural axis abnormalities, hip dysplasia, and congenital heart disease are all associated with the condition; spontaneous correction frequently occurs. Curve progression can be predicted by the rib vertebral angle difference or the phase of the rib head. Rib overlap of the apical vertebral body or a rib vertebral angle difference of greater than 20 degrees indicates that the curve is likely to progress. Gender, family history, and age at presentation have not been found to be risk factors for progression.

Unilateral sacralization of the fifth lumbar vertebra was first described by Bertolotti in 1917. Bertolotti’s syndrome is present in 12% to 21% of the population. The altered biomechanics have been postulated to cause low back pain by placing increased stress on the adjacent cephalad disk, thus contributing to accelerated degenerative disk disease at this level. It has also been found that the neoarticulation between the enlarged transverse process and the sacrum and/or ilium may be a source of neural impingement on the exited L5 nerve root and results in radicular pain syndrome. Brault and associates reported on a case treated surgically at the Mayo Clinic, in which the pain generator was found to be the contralateral facet joint.

Studies have demonstrated that pelvic inclination can dramatically affect the interpretation of radiographs in the dysplastic hip, with 9° of increased pelvic inclination leading to the presence of crossover signs and posterior wall signs. A distance of 30 mm to 50 mm from the sacrococcygeal junction to the pubis is often used to assess the adequacy of pelvic inclination on radiographs. In this patient, the pelvic inclination is dramatically increased, leading to overestimation of acetabular retroversion.

The postoperative incidence of C5 root palsy after laminoplasty ranges from 5% to 12%. Other roots also may be affected. The palsies tend to be motor dominant, although sensory dysfunction and radicular pain are also possible. The palsy may arise during the immediate postoperative period or up to 20 days later. C5 may be preferentially involved because it is at the apex of the cervical lordosis. Recovery usually occurs over weeks to months.

The patient has respiratory distress as manifested by his difficulty in lying flat. In addition, the diaphoresis and the change in his voice indicate retropharyngeal edema or hematoma that is compressing his larynx. The only appropriate treatment is hospital admission and elective intubation. During intubation it is possible to cause laryngospasm in a patient with a hyperacute airway; therefore, the surgeon should be prepared to perform a cricothyroidotomy. Often a fiberoptically guided intubation is the only way to find the airway in the presence of retropharyngeal edema or hematoma.

Tuberculosis of the spine typically has an indolent presentation. Unlike pyogenic infections of the spine, the disk space is usually preserved. Most commonly, the thoracic and lumbar spine are affected. Laboratory studies may be nonspecific. Delayed presentation usually results in neurologic compromise and a kyphotic deformity. Treatment includes a multidrug regimen. Surgery is indicated for deformity correction or failure of medical treatment.

The MRI demonstrates a left paracentral L4/5 disc protrusion which leads to compression of the traversing (descending) left L5 nerve root. Numbness over the dorsal aspect of the foot and weakness to gluteus medius is consistent with an L5 radiculopathy. While nerve root innervation shows some variability by patient, L5 is characteristically responsible for the sensation to the dorsal aspect of the foot, ankle dorsiflexion (tibialis anterior - along with L4), great toe extension (EHL), and hip abduction (gluteus medius). Suri et al. reported on specific physical exam findings that significantly increased the likelihood of nerve root impingement at specific lumbar levels. They found: L2 was associated with decreased anterior thigh sensation. L3 was associated with a positive femoral stretch test. L4 was associated with a blunted patellar reflex, decreased medial ankle sensation or a positive crossed femoral stretch test. L5 was associated with decreased hip abductor strength.

Posterior constructs for Scheuermann’s kyphosis ideally should extend from the most superior to the most inferior aspect of the Cobb angulation. However, the most distal fusion level must be in a stable or lordotic position to avoid the development of junctional kyphosis. Lowe reported that failure to incorporate the first lordotic segment of the lumbar spine is associated with a higher risk of junctional kyphosis. The first lordotic segment of the lumbar spine is typically at least one level below the distal aspect of the curve as measured by the Cobb technique and most commonly is in the upper part of the lumbar spine.

DISCUSSION: The structure illustrated is the sympathetic chain viewed from an anterolateral view of the lower lumbar spine. It descends along the anterolateral aspect of the spine into the pelvis closely adherent to the vertebral column. The spinal nerves, including L5, can be seen exiting from the foramen. The ureters descend from the kidneys and cross anterior to the iliac vessels to the bladder.

Ankylosing spondylitis can lead to progressive autofusion of the vertebrae and significant limitation in motion. Any sudden improvement in motion should be considered a fracture until proven otherwise. These fractures are commonly missed when using plain radiographs or even CT scan because minimal or no displacement often is noted. MR imaging can be useful to identify edema at the fracture site. These fractures are typically very unstable and necessitate surgery to avoid displacement and potential neurologic injury. Some fractures associated with ankylosing spondylitis can be effectively treated with percutaneous pedicle screw fixation. However, because of the highly vascular nature of some of these fractures, they pose a risk for an epidural hematoma, potential neurologic deficit, and emergent decompression.

Gradual desiccation of the disk begins in the third decade as glycosaminoglycan levels within the nucleus begin to decline. The original water content of 88% decreases to 70% in the sixth decade and beyond. As glycosaminoglycan content decreases, there is a corresponding increase in noncollagen glycoprotein.

There is no clear evidence that disk replacement results in pain relief that is superior to fusion. Pain relief appears to be equivalent with these two procedures. No study has clearly demonstrated that normal segmental motion has been consistently restored. Preexisting facet arthropathy is considered to be a contraindication to disk replacement. Comparative long-term data demonstrating a reduced incidence of adjacent segment disease compared to fusion are not yet available.

DISCUSSIONThe radiograph of the lateral lumbosacral spine reveals an isthmic spondylolysis with a Meyerding grade 1 spondylolisthesis. The incidence of spondylolysis in the general population is around 5%, and grade 1 or 2 slips are present in the majority of children with a spondylolysis. Many cases of spondylolysis are painless and discovered incidentally, but, when painful, hyperextension of the lumbar spine may stress the area of the pars defect and exacerbate a patient’s symptoms. A diagnosis can usually be determined with a lateral radiograph of the lumbar spine. Although oblique lumbar radiographs are frequently ordered, several studies have shown that they do not increase diagnostic or prognostic accuracy. Progression of an isthmic spondylolysis, with or without a grade 1 or 2 listhesis, to a serious slip that mightnecessitate surgical intervention is rare and occurs in fewer than 5% of patients. Chance for progression diminishes with age, with patients at highest risk prior to the adolescent growth spurt. Spondylolysis may have a genetic component; an increased prevalence has been found in some families and in some ethnic groups, especially among the Native American population.

This question refers to plantar fascitis. Heel spurs are noted in approximately 50% of the cases of subcalcaneal pain syndrome. In this patient, diagnosis should rule out lumbar radiculopathy since the symptoms are bilateral.The most common site for heel pain is where the plantar fascia and intrinsic muscles arise from the medial calcaneal tuberosity on the anteromedial aspect of the heel.First line treatment is NSAID’s, Physical therapy involving heel cord stretching and an orthosis. Second line therapy after these treatments are unsuccessful involve steroid injection and plaster immobilization. Surgical intervention should be the very last choice in the options given.

DISCUSSION: This patient has symptoms consistent with neurogenic claudication secondary to lumbar spinal stenosis and degenerative spondylolisthesis. Her symptoms are chronic and she has undergone an appropriate course of nonsurgical care. Nevertheless, her symptoms are worsening and surgical intervention is a reasonable consideration. Studies have shown that patients with lumbar spinal stenosis with associated degenerative spondylolisthesis benefit most from decompression of the neural elements that are stenotic and subsequent fusion across the degenerative slip. Anterior lumbar interbody fusion likely will not address stenosis at the level of the slip and may not result in adequate neurologic decompression. Partial laminotomy and diskectomy likely will not provide adequate neural decompression because these procedures would only address unilateral compression and this patient has bilateral issues. Lumbar laminectomy without fusion could be performed but has been associated with results inferior to lumbar laminectomy with fusion when addressing stenosis with spondylolisthesis. RECOMMENDED READINGS: Weinstein JN, Lurie JD, Tosteson TD, Zhao W, Blood EA, Tosteson AN, Birkmeyer N, Herkowitz H, Longley M, Lenke L, Emery S, Hu SS. Surgical compared with nonoperative treatment for lumbar degenerative spondylolisthesis. four-year results in the Spine Patient Outcomes Research Trial (SPORT) randomized and observational cohorts. J Bone Joint Surg Am. 2009 Jun;91(6):1295-304. Herkowitz HN, Kurz LT. Degenerative lumbar spondylolisthesis with spinal stenosis. A prospective study comparing decompression with decompression and intertransverse process arthrodesis. J Bone Joint Surg Am. 1991 Jul;73(6):802-8. Lombardi JS, Wiltse LL, Reynolds J, Widell EH, Spencer C 3rd. Treatment of degenerative spondylolisthesis. Spine (Phila Pa 1976). 1985 Nov;10(9):821-7.

Risk factors associated with low back pain include poor physical fitness, smoking, a history of repetitive bending or stooping on the job, or whole body vibration exposure. Some radiographic factors such as stenosis, spondyloarthropathy, severe deformity, or instability are also associated with low back pain. Gender, weight, transitional anatomy, or facet trophism are not associated with low back pain.

The MRI scans show Modic changes in the L4-L5 vertebral bodies due to spondylosis. There is no increased fluid signal or enhancement in the L4-L5 disk to suggest infection or any other pathologic process. Therefore, the patient’s pain should be treated with a course of physical therapy and rehabilitation. There is no infection; therefore, IV antibiotics and debridement are not indicated. Similarly, apseudomeningocele is not present. A revision diskectomy is useful for recurrent radiculopathy but would not be helpful for degenerative low back pain.(SBQ12SP.29) A 17-year-old female is undergoing posterior instrumented fusion from T5-T12 for adolescent idiopathic scoliosis. At the time of the correction maneuver, the neurophysiologist notifies you of a 60% decrease in somatosensory evoked potential (SSEP) amplitude throughout bilateral lower extremities. Which of the following is an acceptable approach to manage this finding?Review TopicImmediate wake-up test with examination for clonusDrop the mean arterial pressure (MAP) to ~60mmHgDiscontinue instrumentation and optimize MAP to 85mmHg or greaterImmediate infusion of intravenous corticosteroidsModification of the anesthesia plan to include inhalational agents only followed by repeated SSEP testingThe patient has a significant drop in SSEP amplitudes at the completion of the corrective maneuver. The most appropriate response is to raise the MAP to 85 mmHg or greater, discontinue the instrumentation, re-evaluate the SSEPs, and if there is no improvement, to consider reversing the reduction of the deformity.Intra-operative neurophysiologic monitoring is an effective method to monitor insults to the spinal cord and its exiting roots during spinal instrumentation. The common measurements include SSEPs, which monitor sensory potentials transmitted through the dorsal column system, and motor-evoked potentials (MEPs), which monitor motor response to a trans-cranial stimulus. Decreases in amplitude and latency of the circuits are recorded, however diminished signal amplitudes are more sensitive for neurologic injury, and decreases of of >50-60% being highly concerning. The wake-up test involves reversal of anesthesia so that an intra-operative neurologic examination can be performed.Devlin et al. reviewed the basic science and practice of neurophysiologic monitoring in spine surgery. They proposed an algorithmic approach to managing intraoperative alerts which include discontinuation of inhalational anesthetics, increasing the MAP to >90 mmHg, discontinuing instrumentation, and performing a wake-up test if neurologic signals fail to normalize.Herdmann et al. reviewed the practice of neurophysiologic monitoring and the effects of anesthesia upon signal transduction. They report that anesthesia affecting a neuron's intrinsic excitability can alter the results of monitoring. Inhalational anesthetics and decreased MAPs can be responsible for decreased amplitudes.Vitale et. al. developed a consensus-based intraoperative checklist for management of lost neuromonitoring signals. In this checklist, the first steps across the surgical and anesthetic teams should include: stop the case and announce signal losses to the room, optimize the mean arterial pressure, discuss the status of anesthetic agents, and discuss reversible surgical actions just prior to signal loss.Incorrect

The L5 nerve root is especially vulnerable and prone to injury after the reduction of spondylolisthesis in patients with mid-and high-grade isthmic spondylolisthesis. The genitofemoral nerve is more commonly injured during anterior retroperitoneal approaches to the lumbar spine. Injury to the cauda equina often leads to bowel and bladder dysfunction and lower extremity weakness and is uncommon after reduction maneuvers.

The patient has a stable fracture that can be initially treated with bed rest, followed by bracing and quick mobilization. The outcome is good and surgery is not required. These fractures can be treated nonsurgically if there is less than 50% compression, 15 degrees of angulation, and intact posterior structures.