A 16-year-old boy is being evaluated for difficulty walking. On physical examination, he has thoracic scoliosis and multiple small scars on his hands. When asked about these, the boy replies, "I frequently burn my hands by accident because I can't feel the heat." Neurologic examination reveals 1+ biceps reflexes and 3+ patellar reflexes bilaterally, as well as decreased muscle strength in the bilateral upper and lower extremities. His hand muscles are atrophic, and position and vibration senses in the feet are also impaired. Which of the following is the most likely cause of this patient's problems?

Question

A 16-year-old boy is being evaluated for difficulty walking.  On physical examination, he has thoracic scoliosis and multiple small scars on his hands.  When asked about these, the boy replies, "I frequently burn my hands by accident because I can't feel the heat."  Neurologic examination reveals 1+ biceps reflexes and 3+ patellar reflexes bilaterally, as well as decreased muscle strength in the bilateral upper and lower extremities.  His hand muscles are atrophic, and position and vibration senses in the feet are also impaired.  Which of the following is the most likely cause of this patient's problems?

Quizplus · Accepted Answer

11ec160b_39e0_11dc_9249_994f97e3ad60_MD0001_00 This patient has chronic loss of upper extremity pain and temperature sensations, upper extremity weakness and hyporeflexia, lower extremity weakness and hyperreflexia, and kyphoscoliosis. These findings are consistent with syringomyelia. In syringomyelia, a central cystic dilation in the cervical spinal cord (a syrinx) slowly enlarges, characteristically causing damage to the ventral white commissure and anterior horns. The ventral white commissure is the site of decussation of second-order lateral spinothalamic tract neurons, and the ventral horns are the site of lower motor neuron cell bodies. The syrinx is most commonly situated at the C8-T1 cord levels and may extend rostrally, caudally, and centrifugally. Further expansion within the cervical cord in later stages of the disease can produce lower extremity weakness and hyperreflexia (an upper motor neuron defect) by affecting the lateral corticospinal tract and can also lead to loss of position and vibration senses in the feet due to involvement of the posterior columns. Scoliosis can occur due to paresis of paravertebral muscles. (Choice A) Amyotrophic lateral sclerosis is a progressive degenerative disease of upper and lower motor neurons only; it does not cause sensory loss. (Choice B) Guillain-Barré syndrome is a peripheral nervous system autoimmune demyelinating polyneuropathy that typically causes lower motor neuron manifestations (eg, areflexia, weakness) in a symmetric ascending pattern. (Choice C) Medulloblastoma is the most common malignant central nervous system (CNS) tumor in children, with pilocytic astrocytoma, a low-grade astrocytoma, being the most common CNS tumor overall. Medulloblastoma is a posterior fossa tumor that causes symptoms related to obstructive hydrocephalus. (Choice D) Multiple sclerosis is an autoimmune CNS demyelinating disorder that presents with episodic neurologic symptoms reflecting defects in various white matter tracts. (Choice E) Normal pressure hydrocephalus is characterized by gait ataxia and urinary incontinence. It is rare in patients age <60. Defective cerebrospinal fluid resorption by the arachnoid granulations gives rise to the secondary form of this disease. Educational objective: The combination of fixed segmental loss of upper extremity pain and temperature sensations, upper extremity lower motor neuron signs, and/or lower extremity upper motor neuron signs in the setting of scoliosis suggests syringomyelia.

A 16-Year-Old Boy Is Being Evaluated for Difficulty Walking