Myelinated nerve fibres

Published on 02/04/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

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211 Myelinated nerve fibres

Instruction

Examine this patient’s fundus.

Salient features

History

• Asymptomatic.

Examination

• White, streaky patches that extend from the disc and terminate peripherally in a feather-like pattern. It may cover the retinal vessels (Fig. 211.1).

image

Fig. 211.1 Myelinated nerve fibres.

Diagnosis

This patient has white streaky patches in a feather-like pattern (lesion); these are medullated nerve fibres (aetiology) and are benign (functional status).

Questions

What is the pathology?

Occasionally, the myelination of the optic nerve does not stop at the lamina cribrosa but extends on to nerve fibres surrounding the optic disc, terminating peripherally in a feather-like margin with fine striations from the course of the nerve fibre layer. It is a benign congenital abnormality, known as medullated or myelinated nerve fibres, caused by differential myelination. Myelinated retinal nerve fibres occur in 1% of the population and may mimic optic disc swelling or papilledema; an important differentiating feature is the absence of a feathery appearance in true optic disc swelling. The occurrence is bilateral in 17–20% of cases and is continuous with the disk in 81%. Usually, visual acuity is normal, and no particular ophthalmologic follow-up is required.

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211 Myelinated nerve fibres

Instruction

Examine this patient’s fundus.

Salient features

History

• Asymptomatic.

Examination

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