Biomechanical alterations likely play a primary role in causing adjacent segment disease. Radiographically apparent, asymptomatic adjacent segment disease is common but does not correlate with functional outcomes. Potentially modifiable risk factors for the development of adjacent segment disease include fusion without instrumentation, protecting the facet joint of the adjacent segment during placement of pedicle screws,fusion length, and sagittal balance. Surgical management, when indicated, consists of decompression of neural elements and extension of fusion. Outcomes after surgery, however, are modest.

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Lower-extremity pain and paresthesia have multiple origins. Early recognition of the symptoms of peripheral nerve entrapment leads to timely treatment and avoids the cost of unnecessary studies. The authors report on a case of superficial peroneal nerve syndrome resulting from nerve herniation through a fascial defect, which was responsive to surgical treatment. This 22-year-old man presented with pain and paresthesias over the lateral aspect of the right calf and the dorsum of the foot without motor weakness. Exercise led to the formation of a tender bulge approximately 12 cm above the lateral malleolus. Percussion of this site worsened his symptoms. Radiography and electromyography studies were nondiagnostic. The patient underwent surgical decompression that involved division of the fascia overlying the nerve and neurolysis of the superficial peroneal nerve. The operation resulted in symptom-free relief. Superficial peroneal nerve syndrome is an entrapment neuropathy that results from mechanical compression of the nerve at or near the point where the nerve pierces the fascia to travel within the subcutaneous tissue. Surgical decompression of the mechanical entrapment usually provides relief from pain and paresthesia.

Prolonged blindness secondary to tumor-related optic nerve compression may be reversible up to 1 week from onset in children presenting with no light perception.