Variability in the extent of sensory deficit after sural nerve biopsy

BACKGROUND: Sural nerve biopsy (SNBx) is associated with multiple complications such as paresthesia, pain, or numbness in the sural nerve distribution at the site of biopsy and wound infection. An accurate idea of these adverse events would be useful while taking informed consent from patients. AIMS: We conducted a prospective study to determine the extent of sensory deficits after SNBx. SETTINGS AND DESIGN: It is a prospective, hospital-based (tertiary teaching hospital) study. MATERIALS AND METHODS: All the patients who had SNBx between May 2003 and March 2004 were eligible for inclusion. However, patients with sensory impairment in sural nerve territory or abnormal sural nerve conduction studies prior to the procedure were excluded. SNBx was performed in the ankle region under local anesthesia, and a 3 cm nerve segment was excised. Touch, pain, temperature, vibration and joint position were tested after the nerve biopsy. The extent of sensory deficit was determined. Any other complications, when present were also noted. Follow-up assessment was performed at three months or later. RESULTS: Fifty patients (26 women) fulfilled the inclusion and exclusion criteria. The mean age was 37.4 (16-63) years. One-two weeks after the SNBx, 46 (92%) patients had sensory deficit along the lateral aspect of the foot at the site of the biopsy, and 48 (96%) patients had sensory impairment extending beyond the outer aspect of the fifth toe. At follow-up, sensory deficit was present in 89% patients and paresthesia in 39%. CONCLUSIONS: The majority of the patients undergoing SNBx develop persistent sensory deficits, which often extend beyond the typical sural nerve territory.