WASHINGTON, DC—Patients with zinc deficiency-induced peripheral neuropathy may present with paresthesia, gait abnormalities, sensory deficits, reduced tendon reflexes, an abnormal Romberg test, and increased CSF protein, according to a study presented at the 2018 Annual Meeting of the American Association of Neuromuscular & Electrodiagnostic Medicine.
Recognition of the features of zinc deficiency-induced peripheral neuropathy may help neurologists diagnose the disorder and manage patients, researchers said.
“Zinc, an essential trace element, plays a critical role in maintaining normal structural and functional conditions in the body,” said lead author Favio C. Bumanlag, Chief Technologist in the Department of Neurology at the Lewis Katz School of Medicine at Temple University in Philadelphia. “Peripheral nerves are susceptible to damage when zinc deficiency occurs.... Recognition of [zinc deficiency-induced peripheral neuropathy] will help physicians and technologists effectively manage patients.”
To study the clinical and electrophysiologic features of zinc deficiency-induced peripheral neuropathy, Mr. Bumanlag and Jin Luo, MD, PhD, Professor of Neurology and Pharmacology at Temple University, retrospectively reviewed charts in their neuromuscular clinic and EMG laboratory database to identify patients with peripheral neuropathy and zinc deficiency. They included charts from between January 1, 2015, and December 31, 2017, in their review. They excluded patients with abnormal copper levels.
Mr. Bumanlag and Dr. Luo obtained information about patients’ clinical presentations, past medical histories, BMI, neurologic examinations, and laboratory results. They also examined patients’ needle electromyograms and nerve conduction studies.
In all, they identified 12 patients with peripheral neuropathy and zinc deficiency. Patients had a mean age of 55.1. Six were female. Patients’ mean zinc level was 52.5 μg/dL, with a range of 37 μg/dL to 58 μg/dL (reference, 56–134 μg/dL). Mean copper level was 107.6 μg/dL, with a range of 84 μg/dL to 173 μg/dL (reference, 72–166 μg/dL). Eleven of the 12 patients had received an electrophysiologic evaluation.
Notable findings in presentation included paresthesia in 75 and gait abnormalities in 42%. One patient was obese (8%), and three patients had diarrhea (25%). Neurologic examination showed sensory deficits in 83%, reduced tendon reflexes in 67%, and an abnormal Romberg test in 67%. Four of five patients had increased CSF protein. Electrophysiologic evaluations showed features of demyelinating peripheral neuropathy (28%) and distally active denervation in the lower extremities.
“Zinc participates in more than 200 enzymatic reactions,” said the researchers. “Unfortunately, zinc deficiency-induced peripheral neuropathy is often misdiagnosed or delayed in diagnosis. Literature on zinc deficiency-induced peripheral neuropathy is sparse.”