Foot drop secondary to rhabdomyolysis: improved foot dorsiflexion and gait after neurolysis and distal nerve transfer-a case series and literature review

Abstract

Rhabdomyolysis is a triad syndrome of myalgia, muscle weakness and myoglobinuria due to muscle necrosis. Trauma, exertions, strenuous exercise, infections, metabolic and electrolyte disorders, drug overdoses, toxins and genetic defects are the most common causes of rhabdomyolysis. The etiologies of foot drop are diverse. A few cases of rhabdomyolysis-associated foot drop are reported in the literature. We present five patients with foot drop secondary to rhabdomyolysis; two underwent neurolysis and distal nerve transfer (superficial peroneal nerve to the deep peroneal nerve) surgeries and follow-up evaluations. We found five-foot drop patients secondary to rhabdomyolysis among the 1022-foot drop patients who consulted our clinic since 2004, representing a 0.5% incidence. In two patients, rhabdomyolysis was caused by drug overdose and abuse. In the other three patients, the causes were an assault with a hip injury, a prolonged hospitalization due to multiple illnesses, and an unknown cause with compartment syndrome. Pre-operatively, a 35-year-old male patient had aspiration pneumonia, rhabdomyolysis and foot drop resulting from prolonged ICU hospitalization and a medically induced coma due to a drug overdose. The second patient (a 48-year-old male) had no history of trauma but had a sudden onset of right foot drop after compartment syndrome following the insidious onset of rhabdomyolysis. Both patients had difficulty dorsiflexing their involved foot and walked with a steppage gait before surgery. In addition, the 48-year-old patient had foot slapping while walking. However, both patients had strong plantar flexion (5/5). After 14 and 17 months of surgery, both patients had improved foot dorsiflexion to an MRC grade of 4/5 with an improved gait cycle and walked with no or minimal slapping, respectively. Distal motor nerve transfers in the lower limb facilitate faster recovery and less surgical dissection because of the shorter regeneration distance from the donor axons to the targeted motor end plates through residual neural network connections and descending motor signals.