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Aristotelis S. Filippidis, M. Yashar Kalani, Nicholas Theodore and Harold L. Rekate

Object

The definition of tethered cord syndrome (TCS) relies mainly on radiological criteria and clinical picture. The presence of a thickened filum terminale and a low-lying conus medullaris in symptomatic patients is indicative of TCS. The radiological definition of TCS does not take into account cases that involve a normal-lying conus medullaris exhibiting symptoms of the disease.

Methods

The authors performed a MEDLINE search using the terms “tethered cord” and “pathophysiology.” The search returned a total of 134 studies. The studies were further filtered to identify mostly basic research studies in animal models or studies related to the biomechanics of the filum terminale and spinal cord.

Results

Spinal cord traction and the loss of filum terminale elasticity are the triggers that start a cascade of events occurring at the metabolic and vascular levels leading to symptoms of the disease. Traction on the caudal cord results in decreased blood flow causing metabolic derangements that culminate in motor, sensory, and urinary neurological deficits. The untethering operation restores blood flow and reverses the clinical picture in most symptomatic cases.

Conclusions

Although classically defined as a disease of a low-lying conus medullaris, the pathophysiology of TCS is much more complex and is dependent on a structural abnormality, with concomitant altered metabolic and vascular sequelae. Given the complex mechanisms underlying TCS, it is not surprising that the radiological criteria do not adequately address all presentations of the disease.

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Seref Dogan, Sam Safavi-Abbasi, Nicholas Theodore, Eric Horn, Harold L. Rekate and Volker K. H. Sonntag

Object

In this study the authors evaluated the mechanisms and patterns of injury and the factors affecting management and outcome of pediatric subaxial cervical spine injuries (C3–7).

Methods

Fifty-one pediatric patients (38 boys and 13 girls; mean age 12.4 years, range 10 months–16 years) with subaxial cervical spine injuries were reviewed retrospectively. Motor vehicle accidents (MVAs) were the most common cause of injury. Overall, 12% presented with a dislocation, 63% with a fracture, 19% with a fracture–dislocation, and 6% with a ligamentous injury. The most frequently injured level was C6–7 (33%); C3–4 (6%) was least frequently involved. Sixty-four percent of patients were neurologically intact, 16% had incomplete spinal cord injuries (SCIs), 14% had complete SCIs, and three patients (6%) died after admission and before assessment. Treatment was conservative in 64%: seven (13%) wore a halo vest and 26 (51%) wore a rigid cervical orthosis. Surgery was performed in the other 18 patients (36%), with the breakdown as follows: 15 (30%) underwent an anterior approach, two (4%) had posterior approaches, and one (2%) had a combined approach. Postoperatively, four patients (8%) who had a neurological deficit improved. The overall mortality rate was 8%; all deaths were related to MVAs. There were no surgery-related deaths or complications.

Conclusions

Subaxial cervical spine injuries are common in children 9 to 16 years of age, and occur principally between C-5 and C-7. Multilevel injury is more common in children 8 years of age and older than in younger children and infants. Most patients with subaxial cervical spine injuries can be treated conservatively. Both anterior and posterior approaches are safe and effective.

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Skeletal dysplasia involving the subaxial cervical spine

Report of two cases and review of the literature

Gregory P. Lekovic, Nitin R. Mariwalla, Eric M. Horn, Steven Chang, Harold L. Rekate and Nicholas Theodore

✓ Because skeletal dysplasias are primary disorders of bone, they have not been commonly understood as neurosurgical diseases. Nevertheless, neurosurgical complications are commonly encountered in many cases of dysplasia syndromes. The authors present two cases of skeletal dysplasia that caused overt instability of the cervical spine. One patient with a diagnosis of Gorham disease of the cervical spine was treated with prolonged fixation in a halo brace after an initial attempt at instrumentation with a posterior occiput–C4 fusion. The other patient, who at birth was identified to have camptomelic dysplasia, has been treated conservatively from the outset. Although these two patients presented with different disorders—in one patient adequate mature bone never formed and in the other patient progressive bone loss became apparent after a seemingly normal initial development—these cases demonstrate unequivocally that surgical options for fusion are ultimately limited by the quality of the underlying bone. In patients in whom the bone itself is inadequate for use as a substrate for fusion, there are currently limited treatment options. Future improvements in our understanding of chondrogenesis and ossification may lead to the design of superior methods of encouraging fusion in these patients; however, at the present time, long-term maintenance in a halo brace may, in fact, be the only treatment.