Sophia M. Thompson, BA
Medical Student
Eastern Virginia Medical School
Norfolk, Virginia, United States
Taylor M. Drake, MD
Resident
EVMS
Virginia Beach, Virginia, United States
Mark Caramore, MD
Assistant Professor
Macon and Joan Brock Virginia Health Sciences at Old Dominion University
Norfolk, Virginia, United States
45-year-old male presented to the clinic with a four-month history of chronic, progressively worsening pain and numbness in his lower extremities. His symptoms began with a pinching sensation in his lower back while bending forward, followed by numbness and tingling that have steadily worsened. Notably, he had been diagnosed and treated for Rocky Mountain Spotted Fever (RMSF) five months prior.
On examination, sensation was diminished bilaterally in the L3-S2 dermatomes, though muscle strength remained intact. Nerve conduction studies (NCS) revealed severe, diffuse impairment in both the upper and lower extremities. Bilateral peroneal and tibial motor studies demonstrated significantly prolonged onset latency, reduced amplitude, and temporal dispersion, with similar findings observed in the right upper extremity. The left tibial motor and lower extremity sensory nerves were non-responsive. Despite these marked nerve conduction abnormalities, electromyography (EMG) only showed concerns of active denervation in the right posterior tibialis and gastrocnemius.
Discussions:
The patient’s case presents a diagnostic challenge, as his electrodiagnostic findings were unexpected in the context of his clinical exam. The study strongly suggests a demyelinating polyneuropathy of uncertain origin. The patient has no family history of hereditary neuropathies, but given his recent history of (RMSF) and the observed NCS pattern, there is a significant possibility of mononeuritis multiplex vasculitis. Untreated, it can cause permanent nerve damage, severe functional impairment, and worsening of the underlying condition. Although the clinical presentation also resembles Chronic Inflammatory Demyelinating Polyneuropathy (CIDP), the preservation of reflexes makes CIDP less likely. Furthermore, the patient's history of unintentional weight loss adds another layer of complexity, raising suspicion for a possible paraneoplastic syndrome.
Conclusions:
In cases where an electrodiagnostic study reveals severe demyelination and axonal loss, the provider must maintain a wide differential diagnosis to ensure a comprehensive history, physical exam, and diagnostic work-up.
