Reversible cerebral and brain stem dysfunction in n: Hexane neuropathy

Abstract

A 18-year-old male, screen printer by profession developed sensory motor polyneuropathy, change in his behavior, bilateral 6(th) and 7(th) cranial nerve palsies, down beat nystagmus and cerebellar dysarthria. He had bilaterally prolonged P100 latency; left: 137 ms; right: 144 ms. P 37 was not recordable on either side while N 20 was normal. The inter latency difference between Ipsilateral R2 and Contralateral R2 was 6.15 ms, on the left side and normal on the right side. In the follow-up, there was normalization of the blink reflex study, improvement in P100 latency [left: 114 ms; right: 120 ms.] but worsening of peripheral nerve conductions. The sequential clinical recovery was of the behavioral dysfunction, down beat nystagmus, 6(th) nerve, 7(th) nerve involvement and ataxia, in that order. Sural nerve biopsy showed loss of large diameter myelinated fibers.

Keywords: 6th and 7th nerve palsy; blink reflex; central nervous system involvement; down beat nystagmus; n- Hexane neuropathy.

Figure 1

P 100 latency of pattern evoked visual responses: At presentation; (a) Left, 137 ms, (b) Right 144 ms, After 70 days; (c) Left, 114 ms, (d) Right, 120 ms

Figure 2

Blink reflex after stimulation of left supra orbital nerve: (a) At presentation R1 was 10.55 ms, R2, 34.3 ms, Contra lateral R 2, 40.45 ms; on direct facial nerve stimulation, latency was 2.85 ms, (b) After 70 days; R1 was 11.25 ms, R2, 39.6 ms, Contra lateral R 2, 41.7 ms; on direct facial nerve stimulation, latency was 3.5 ms

Figure 3

20× Immunohistochemistry for Myelin Basic Protein of sural nerve showing near total loss of large diameter myelinated fibers with few preserved small diameter myelinated fibers