Peripheral nerve biopsy remains an essential tool in diagnosing complex neuropathies, yet its diagnostic yield can be inconsistent. A study by Kopanidis et al. evaluates the pre-biopsy clinical parameters that may enhance biopsy selection and improve diagnostic outcomes in neuropathies with high indications for nerve biopsy, including vasculitis, neurolymphomatosis, amyloidosis, and sarcoidosis. The study retrospectively examined 64 patients who underwent nerve biopsy in Oxford, England. Patients were divided into a diagnostic group (including vasculitis, granulomatous, and infiltrative neuropathies) comprising 32.8% of cases, and a non-specific group with inconclusive results (46.9%).
Several key clinical parameters were associated with a higher likelihood of obtaining a diagnostic biopsy result, including shorter disease duration (mean disease duration of 10 months in the diagnostic group vs 38 months in the non-specific group) and stepwise progression (81% vs 20%). Mononeuritis multiplex was significantly more common in the diagnostic group (57.1% vs 10%), as was asymmetry in presentation (90.5% vs 60%). Neuropathic pain was more prevalent in the diagnostic group (85.7% vs 56.7%). Laboratory findings such as elevated white cell count (47.6% vs 16.7%) and positive p-ANCA (19.1% vs 0%) correlated with positive biopsy findings.
Peripheral nerve imaging (MRI/US) abnormalities were detected in 77.8% of patients in the diagnostic group, suggesting that pre-biopsy imaging could serve as a useful adjunct to patient selection. Of note, ultrasound plays an important role in detecting nerve enlargement, focal thickening, and inflammatory changes, aiding in the selection of the most appropriate nerve for biopsy.
Nerve conduction studies in the diagnostic group revealed exclusively axonal features in the majority of patients, while others exhibited additional demyelinating features alongside axonal polyneuropathy. However, the study suggests that neurophysiology (including nerve conduction studies and electromyography) does not significantly differentiate between diagnostic and non-specific biopsy groups, limiting its role in guiding biopsy site selection.
The article provides quality improvement measures to enhance the clinical utility of nerve biopsy combining clinical, laboratory, and imaging data for better biopsy outcomes and including electron microscopy for deeper insights.
Key Points:
- Prioritize cases with stepwise disease progression, shorter duration, and mononeuritis multiplex for nerve biopsy.
- Multidisciplinary assessment is advised, including imagining techniques followed by input from a neurologist, pathologist, imaging expert, and surgeon .
- Clinical neurophysiology has limited value in distinguishing appropriate candidates for nerve biopsy.
References:
- Kopanidis P, Baskozos G, Byrne E, et al. Utilising clinical parameters to improve the selection of nerve biopsy candidates. Intern Med J. 2023;53(12):2224-2230. doi:10.1111/imj.16099
- Nathani D, Spies J, Barnett MH, et al. Nerve biopsy: Current indications and decision tools. Muscle Nerve. 2021;64(2):125-139. doi:10.1002/mus.27201
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