Weak in the Knees

A CLINICAL PROBLEM-SOLVING article by Walter Conwell from University of Colorado, Denver.
A 61-year-old woman presented to her primary care physician with a 4-week history of progressive leg weakness, bilateral leg pain, and difficulty walking. The weakness was symmetric, and did not fluctuate during the course of the day. The patient also reported depression, anxiety, memory problems, and intermittent headaches that had begun several months earlier. She had a dry mouth but no difficulty swallowing. Previously very active, she had become homebound over a period of several months because of the leg weakness.
On examination, she had moderate weakness in hip flexion and in knee flexion and extension bilaterally. Strength in the feet, ankles, hands, and arms was normal. Knee and ankle reflexes were normal, and plantar reflexes were flexor bilaterally. Sensation of light touch and vibratory sensation were normal throughout her body.
During the following 2 months, her symptoms progressed, and she required a walker to ambulate. Arm weakness, difficulty eating without assistance, and increasing memory problems also developed.
Nonspecific symptoms such as weakness can pose a diagnostic challenge for even the most astute clinicians. In this case which involved an uncommon disorder, the key was to carefully consider all the available information in order to identify patterns that pointed to specific diagnoses and ruled out others.