Pediatric Nerve Biopsy Diagnostic and Treatment Utility in Tertiary Care Referral.

Background: Pediatric neuropathies are both unique and similar to their adult counterparts, with genetic varieties thought to be more common. The objective of this work was to assess the utility of nerve biopsy in children at a tertiary referral center in light of availability of current genetic testing.

Methods: We retrospectively reviewed the clinical, nerve biopsy, and genetic testing findings of 316 pediatric (age ≤18 years) patients.

Results: Median age at diagnosis was 9.8 years (4 days to 18 years). Nerve biopsy was nontargeted in 198 (182 whole sural, seven superficial peroneal, and nine other), targeted in 21 (14 fascicular sciatic and seven brachial plexus), and unknown in 97 cases. Prebiopsy localizations and diagnoses were diverse, most commonly with length-dependent localizations (n = 150). Median follow-up was 6 months (0 to 480 months). A distinctive histopathologic diagnosis was made in 106 cases (33%), including inflammatory or immune (n = 30), neoplastic (n = 19), hereditary (n = 41), vasculitis (n = 10), and other (n = 6). Nerve biopsy confirmed the suspected diagnosis in 91 (29%) individuals and changed or refined the initial diagnosis in 182 (58%). Treatment modifications as a result of biopsy occurred in 80 (25%) cases; 59 (19% of the entire cohort) with clinical improvements noted, most commonly by immunotherapy (n = 30). Low diagnostic yield occurred in "hypotonic infants" without nerve conduction abnormalities. Pain at the biopsy site beyond 1 month was rare (n = 3; 1%). Forty-four patients underwent genetic testing. Among demyelinating varieties, mutations were identified in five of 11 (46%) cases compared with only six of 33 (18%) cases of axonal varieties.

Conclusion: Pediatric nerve biopsy provides diagnostic information that frequently alters treatment recommendations. Furthermore, it leads to clinical improvements, especially in inflammatory immune neuropathies. For suspected inherited varieties, genetic testing has the highest diagnostic yield in demyelinating phenotypes.