6. Spine MCQs

The patient with cauda equina syndrome should be taken to surgery urgently to provide the best chance of symptom resolution. However, many studies indicate that patients with cauda equina syndrome do not return to a completely normal status even following urgent surgery. Whereas pain is typically relieved after surgery, other deficits, especially bladder and sexual dysfunction, may persist. Particularly in light of the patient's severe saddle anesthesia, she may have a poor prognosis for recovery of normal bladder function.

DISCUSSION: Typically, posterior spinal fusion to the pelvis is recommended for patients with spinal muscular atrophy and advanced scoliosis. Examination for lower extremity muscle contractures is important because the contractures may interfere with good sitting balance. Anterior release and fusion usually are not advised. Diaphragmatic pacing is not indicated because diaphragm function usually is not affected. Patients with spinal muscular atrophy usually are not ambulatory or only marginally ambulatory at the time of scoliosis surgery; therefore, gait analysis usually is not relevant. While a muscle biopsy may have a role in the diagnosis of this disorder, it plays no subsequent role in determining life expectancy or the value of spinal surgery. REFERENCES: Daher YH, Lonstein JE, Winter RB, Bradford DS: Spinal surgery in spinal muscular atrophy. J Pediatr Orthop 1985;5:391-395. Aprin H, Bowen JR, MacEwen GD, et al: Spinal arthrodesis in patients with spinal muscle atrophy. J Bone Joint Surg Am 1982;64:1179-1187.

The patient has a stable L2 burst fracture. There is no evidence of neurologic injury or disruption of the posterior ligamentous complex. According to the Thoracolumbar Injury Classification System (TLICS), the severity score for this injury is 2 and therefore nonsurgical management is recommended. The TLICS was developed to define injury based on three clinical characteristics: injury morphology, integrity of the posterior ligamentous complex, and neurologic status of the patient. Point values are assigned to each major category based on injury severity. The sum of these points represents the TLICS severity score, which may be used to guide treatment. The injury scores are totaled to produce a management grade that is, in turn, used to guide treatment. A score of >4 suggests the need for surgical treatment because of significant instability, whereas a score of <4 suggests nonsurgical management. The severity score offers prognostic information and is helpful in medical decision making. An external orthosis provides enough support to obviate the need for bed rest and avoid associated complications (deep venous thrombosis, pulmonary embolism, pneumonia, skin ulceration). Surgical treatment, either through an anterior or posterior approach, has been shown by Wood and associates to result in increased pain and disability and is therefore not indicated in this setting. Additionally, there is no need for decompression in the setting of a neurologically intact patient.

The magnitude of the curve at the time of the peak height velocity is the most prognostic sign in relationship to surgery. More than 70% of curves that measure more than 30 degrees at this time are likely to reach surgical range.

MRI findings following SCI treated with high dose steroids have demonstrated that the steroids are associated with a lower extent of cord hemorrhage. No difference in cord edema was found. The decreased cord hemorrhage seen with use of high dose steroid adminstration in this setting has not correlated with improved clinical outcomes.

A true compression fracture is a single-column injury that does not create canal compromise. A burst fracture is a two- or three-column injury that disrupts the middle column and thereby narrows the spinal canal. This patient has a burst fracture. The mechanism of injury is usually vertical compression or flexion compression.

DISCUSSION: This patient has disk herniation at the left L5-S1 level. This will generally affect the traversing S1 nerve. The S1 dermatome is on the lateral aspect and sole of the foot. Surgical treatment generally involves a diskectomy with removal of the herniated fragment. This can be performed via a conventional open approach or minimally invasive endoscopic technique. Several recent meta-analyses have demonstrated equivalent outcomes with regard to leg pain and clinical outcomes. Although minimally invasive techniques have been associated with an increased rate of dural tear, the overall complication rate between the 2 techniques is not significantly different. Several studies have demonstrated a substantial learning curve associated with minimally invasive techniques, and the rate of complications decreases significantly with surgeon experience. When performing a diskectomy, the herniated fragment alone can be removed (sequestrectomy) or some of the disk that remains in the disk space can be removed (complete diskectomy). Studies have shown no change in surgical time, blood loss, length of stay, or surgical complications when performing a sequestrectomy (compared to a more complete diskectomy). A sequestrectomy is associated with a higher rate of recurrent disk herniation at the surgical level.

When planning surgical intervention for Scheuermann kyphosis, it is imperative that the instrumentation and fusion extend across the entirety of the deformity. Distally, this means extending across the first lordotic disk space. In this scenario, this disk is the L1-L2 disk, which means the fusion needs to extend to L2. Shorter and longer fusions are not necessary or appropriate.

Mild scoliosis is not a painful condition, but it usually presents during adolescence. Intermittent back pain is reported by 25% to 30% of adolescents whether or not scoliosis is present. Such pain is often attributed to muscle strain from tight muscles, poor posture, or heavy school backpacks. The clinician must distinguish typical pain (mild, intermittent, nonlimiting) from atypical pain. The latter requires more careful examination and imaging studies (bone scan or MRI) to determine the source of pain. The patient’s age and right thoracic curve pattern are typical for idiopathic scoliosis; therefore, imaging of the neuroaxis is not necessary to look for cord syrinx, tethering, or tumor. Brace treatment is not required for this small curve unless future progression is demonstrated.

The plain radiograph and tomogram show an abnormality of the upper cervical spine, with erosion of the dens. The MRI scan shows evidence of cord impingement. The cervical spine is frequently involved in polyarticular JRA. Stiffness and autofusion are commonly seen, but C1-2 instability can also occur secondary to synovitis and bony erosion. Basilar invagination is rare in JRA. There is no consensus regarding fusion in the asymptomatic patient. In patients with symptoms and neurologic signs, C1-2 posterior fusion is indicated.

Osteoporosis can affect all aspects of spinal stability and is the most critical factor regarding spinal implant failure. Burring of the end plates may decrease strength of the interface with the uncovering of "softer" cancellous bone. Increasing the surface contact area may help prevent subsidence but is not as important as bone quality. Stress shielding through rigid fixation may lead to construct failure.

In general, a previously healthy patient with an acute onset of nontraumatic lower back pain does not need diagnostic imaging before proceeding with therapeutic treatment. In the absence of any “red flags” during the history and physical examination, such as trauma or constitutional symptoms (ie, fevers, chills, weight loss), the appropriate treatment for acute onset lower back pain is purely symptomatic treatment including limited analgesics and early range of motion. Diagnostic imaging is not necessary unless the initial treatment is unsuccessful and symptoms are prolonged. Miller and associates suggested that the use of radiographs can lead to better patient satisfaction but not necessarily better outcomes.

DISCUSSION: Sexual dysfunction is a common condition after extensive anterior lumbar surgical dissection. Erectile dysfunction usually is nonorganic but may be related to parasympathetic injury. The parasympathetic nerves are deep in the pelvis at the level of S2-3 and S3-4 and usually are not involved in the surgical field for anterior L4-5 and L5-S1 procedures. Retrograde ejaculation is the result of injury to the sympathetic chain on the anterior surface of the major vessels crossing the L4-5 level and at the L5-S1 interspace. Erectile function and orgasm are not affected by sympathetic injury. The pudendal nerve is primarily a somatic nerve and is not located in the surgical field.

rhBMP-2 is FDA approved for use together with the lumbar tapered fusion device (LT Cage; Medtronic) in single-level ALIF from L2 to S1 levels in degenerative disc disease. rhBMP-2 is also FDA approved for use in open tibial shaft fractures stabilized with an IM nail and treated within 14 days of initial injury. Burkus et al. prospectively compared 46 patients undergoing single-level ALIF with BMP-2 vs with autograft in an industry sponsored study. They found that patients receiving BMP-2 had higher rates of fusion and improvement in pain and neurologic status at 12 and 24 months compared with autograft, and there were no adverse events.

DISCUSSION: Congenital anomalies of the spine, including failure of formation and failure of segmentation, are associated with other anomalies in other organ systems that develop at the same time. These include anomalies in the genitourinary system, cardiac anomalies, Sprengel’s deformity, radial hypoplasia, and gastrointestinal anomalies including imperforate anus and trachealesophageal fistula. Spinal dysraphism is the most common associated abnormality. Neural axis lesions may be associated with visible midline abnormalities such as a hairy patch or nevus. The child has already had a cardiac and renal work-up, and based on the findings of the hairy patch and congenital vertebral anomalies, MRI of the entire spine is prudent at this time.

A C6-7 herniated nucleus pulposus is most likely to produce a C7 radiculopathy resulting in pain at the forearm and hand, numbness of the middle finger, and weakness of the triceps and finger extensors. Alternative answers represent sequelae of symptomatic disk herniations at C3-C4 (1), C4-C5 (2), C5-C6 (3), and C7-T1 (5), respectively.(SBQ12SP.27) A 24-year-old male sustains the injury shown in Figure A. What was the most likely mechanism of injury?Review TopicHyperextensionFlexion-distractionFlexion-compressionRotationalPure axial loadFigure A shows a quadrangular fracture pattern of C5. These injuries are observed with flexion-compression loads.Quadrangular fractures of the cervical spine are considered flexion teardrop fractures. However, they present with a larger anterior lip fragment compared to the classic teardrop fracture pattern. The radiographic findings include a quadrangular-shaped fragment from the anterior one-third of the vertebral body with significant posterior vertebral subluxation, angular kyphosis, and an increased interspinous space with facet subluxation due to disruption of the posterior elements. These are unstable fractures, and almost always require anterior and posterior stabilization.Moore et al. studied the reliability of Cervical Spine Injury Severity Score to measure stability after cervical spine trauma. The classification system is based on morphologic descriptions and, secondly, on stability based on a quantifiable value. They showed that the Cervical Spine Injury Severity Score had excellent reliability with intra-observer intraclass correlation coefficients (ICC) >0.97 and inter-observer ICC >0.88.Vaccaro et al. published the subaxial cervical spine injury classification system (SLIC). This systems involves 3 main categories (injury morphology, disco-ligamentous complex, and neurologic status). The overall injury severity score is obtained by summing the scores from each category. They propose that SLIC < 4 can be treated non-operatively.Allen et al. published a classification system of cervical spine injuries which breaks injuries of the subaxial spine into six phylogenic groups based on mechanism of injury. These include: 1) flexion-compression 2) vertical-compression 3) flexion-distraction 4) extension-compression 5) extension-distraction 6) lateral flexion. Facetdislocationiscausedbyflexion-distractionforce.Figure A shows a lateral radiograph of the cervical spine demonstrating a typical flexion-compression fracture with anteriorly displaced quadrangular fragment. Illustration A shows a flexion-compression injury. Illustration B shows the mechanism of injury for a quadrangular fracture of the cervical spine. This unstable fracture pattern is characterized by anterior column failure in flexion/compression and posterior column failure in tension. Illustration C shows an illustration of the fracture morphology according to the Allen and Ferguson classification.Incorrect Answer 1:Hyperextension injuriesFlexion-distraction injuries usually result in facet dislocations.

The Hoffman sign is the most common finding, occurring in 80% of myelopathic patients, and it is more common with increasing severity of the myelopathy. The prevalence of hyperreflexia has been shown to be no different from the prevalence in individuals without myelopathy. Sustained clonus and Babinski signs have been shown to occur in only one third of the patients with myelopathy.

DISCUSSION: The patient has a cauda equina syndrome. The fact that he has decreased rectal tone and urinary retention suggests the need for urgent surgery. Patients who are left untreated will have a poor prognosis for return of function. Although most patients who have insidious onset of symptoms with urinary retention will regain normal motor function following decompression, nearly one third will continue to have abnormal voiding patterns or sexual dysfunction of varying degrees. REFERENCES: Kostuik JP, Harrington I, Alexander D, Rand W, Evans D: Cauda equina syndrome and lumbar disc herniation. J Bone Joint Surg Am 1986;68:386-391. Wisneski RJ, Garfin SR, Rothman RH, Lutz GE: Lumbar disk disease, in Herkowitz HN, Garfin SR, Balderston RA, et al (eds): The Spine, ed 4. Philadelphia, PA, WB Saunders, 1992, vol 1, pp 613-679.

The cervical medullary junction should be 135° or greater. An angle of 125° suggests compression of the cervical medullary junction. Other findings supporting surgical intervention include a cord diameter in flexion of less than 6 mm or less than 13 mm of space available for the cord.

Although thoracic disk herniations have been reported at all levels of the thoracic spine, more than two thirds are found at T9-T12, which is the more mobile lower third of the thoracic region.