The involvement of optic and auditory pathways has rarely been studied in demyelinating polyneuropathies. A cohort of patients with acquired and genetic demyelinating neuropathy has been studied.
The study has involved eight patients with hereditary neuropathy with liability to pressure palsies ( HNPP ), six with Charcot-Marie-Tooth disease type 1A ( CMT1A ), ten with chronic inflammatory demyelinating polyneuropathy ( CIDP ) and seven with antimyelin-associated glycoprotein ( MAG ) neuropathy using visual evoked potentials and brainstem auditory evoked potentials.
Optic pathway dysfunction was detected in 6/7 anti-MAG neuropathy patients, about half of those with CIDP and HNPP, but only in 1/6 patients with CMT1A.
Peripheral auditory nerve dysfunction appeared common in all groups except HNPP. Brainstem involvement was exceptional in all groups.
In conclusion, optic nerve involvement may be frequent in all demyelinating polyneuropathies, particularly anti-MAG neuropathy, except in CMT1A.
Peripheral auditory nerves may be spared in HNPP possibly due to absence of local compression. Evidence for central brainstem pathology appeared infrequent in all four studied neuropathies.
The study suggests that acquired and genetic demyelinating polyneuropathies may be associated with optic and auditory nerve involvement, which may contribute to neurological disability, and require greater awareness. ( Xagena )
Knopp M et al, Acta Neurol Scand 2014; Epub ahead of print