Subclinical brainstem involvement in peripheral polyneuropathies

Abstract EN

The objective of this study was to investigate the subclinical brainstem involvement in patients presenting with peripheral polyneuropathy (PN).

Patients and methods Patients with various disorders presenting with clinical manifestations of PN were evaluated by routine sensory and motor nerve conduction studies and only patients with electrophysiologically documented PN were included in this study.

Patients with a previous history of cranial nerve lesions and stroke were excluded.

Seventy-eight patients and 30 age-matched and sex-matched healthy individuals were included for the evaluation of blink reflex (BR).

BRs were obtained after bilateral electrical stimulation of the supraorbital nerve for quantitative analysis of three responses, early ipsilateral component (R1), late ipsilateral (R2i), and late contralateral (R2c).

Results R1, R2i, and R2c latencies were prolonged and of low amplitude in diabetic patients with PN.

Fifty percent of cancer patients with PN had abnormally delayed BR responses.

R1 was delayed in 58.3% of patients with chronic renal failure and it was associated with prolonged R2i and R2c latencies in 41.6% of those patients.

In 53.8% of patients with hypothyroidism, R2i and R2c latencies were prolonged whereas R1 latency was normal.

Sixty percent of patients with hereditary motor sensory neuropathy had prolonged latency of at least one component of the BR responses.

Three patients with scleroderma had markedly low amplitude but normal latency BR responses.

Conclusion Subclinical involvement of the facial, trigeminal nerves, and brainstem may occur in patients with various disorders presenting with PN, which could be identified by easy and noninvasive BR testing.