Case Discussion: Headaches and Loss of Vision

Introduction

This is the case history of MP, a 12 year old male who presented to hospital with a 2 week complaint of headaches, associated with complete loss of vision in his left eye.

The headaches were isolated to the left temporal region (no radiation), rated 9 out of 10 in severity and described as a pounding pain. There was no associated prodrome or aura, inclusive of nausea and vomiting. This headache was associated with left retro-orbital pain (8/10 in severity) that persisted throughout his headaches and Loss of Vision. Roughly 3 days later he was told that his affected eye was outward and upward, and once noticed that it appeared larger than the contralateral side.

His loss of vision occurred suddenly and was described as complete (no light perception in any quadrant, no appreciation of movement) with no erythema or tearing.

Review of systems and past Medical history were both unremarkable. The only significant family history is of a Grandmother who suffers from Migraines, and an Aunt with Glaucoma.

Examination findings :

Cranial Nerve examination - Funduscopy showed mild pallor of the affected Optic disc, with a healthy appearing vasculature and Macula.

Pupillary examination - Apparent RAPD of the left pupil (slowly reactive to light on direct reflex, nil consensual reflex). Normal function of CN 3,4,6 (nil diplopia).

Field examination improved from nil light perception to movement perception at 10 inches to light perception and then return of superior, inferior and peripheral fields.

Normal reflexes, tone and power, with intact coordination speech and gait.

What are your thoughts?

He was managed primarily with a 3 day course of Intravenous Methylprednisolone.

Neurology input suggested Csf studies which were largely unremarkable except for the cell count which had a Neutrophillia. Hence he was also commenced on once daily Intravenous Antibiotics as well. For further investigation, he had Visual Evoked Potentials, which were still outstanding.

Ophthalmic evaluation continued, as the initial diagnosis of retrobulbar Optic Neuritis was made on their part.

Teaching Points :

Why the VEP?

Background

Devic’s disease, also known as neuromyelinitis optica (NMO), is a severe, rare demyelinating disorder, previously considered to be a form of multiple sclerosis (MS). The aim of this study was to present the case report of 21-year-old woman with a very early diagnosis of Devic’s disease, established following electrophysiological testing.

Case Report

A 21-year-old woman was referred to Warsaw Medical University, Department of Ophthalmology, with subjective visual impairment. The patient underwent a full clinical examination, colour vision and Goldmann visual field testing, fluorescein angiography, OCT, multifocal ERG, and visual evoked potentials (VEPs).

Conclusions

Visual evoked potentials are a very useful diagnostic tool in optic nerve neuropathies. In our patient, the electrophysiological testing allowed us to establish a proper diagnosis very early, before typical clinical signs of Devic’s disease.

Why Retrobulbar Optic Neuritis?

RAPD Explained:

In a normal swinging light test (i.e. there is no RAPD) the pupils of both eyes constrict equally regardless of which eye is stimulated by the light. In an abnormal swinging-light test (i.e. there is a RAPD) there is less pupil constriction in the eye with the retinal or optic nerve disease.

Steps

• Use a bright torch which can be focussed to give a narrow, even beam of light. Perform the test in a semi-darkened room. If the room is too dark it will be difficult to observe the pupil responses, particularly in heavily pigmented eyes.

• Ask the patient to look at a distant object, and to keep looking at it. Use a Snellen chart, or a picture. This is to prevent the near-pupil response (a constriction in pupil size when moving focus from a distant to a near object). While performing the test, take care not to get in the way of the fixation target.

• Move the whole torch deliberately from side to side so that the beam of light is directed directly into each eye. Do not swing the beam from side to side around a central axis (e.g. by holding it in front of the person's nose) as this can also stimulate the near response.

• Keep the light source at the same distance from each eye to ensure that the light stimulus is equally bright in both.

• Keep the beam of light steadily on the first eye for at least 3 seconds. This allows the pupil size to stabilise. Note whether the pupil of the eye being illuminated reacts briskly and constricts fully to the light. Also note what happens to the pupil of the other eye: does it also constrict briskly?

• Move the light quickly to shine in the other eye. Again, hold the light steady for 3 seconds. Note whether the pupil being illuminated stays the same size, or whether it gets bigger. Note also what happens to the other eye.

• As there is a lot to look at, repeat the test, observing what happens to the pupils of both eyes when one and then the other eye is illuminated.

When the test is performed on someone with unilateral or asymmetrical retinal or optic nerve disease, a RAPD should be present. The following happens:

• When the light is shone into the eye with the retinal or optic nerve disease, the pupils of both eyes will constrict, but not fully. This is because of a problem with the afferent pathway.

• When the light is shone into the other, normal (less abnormal) eye, both pupils will constrict further. This is because the afferent pathway of this eye is intact, or less damaged than that of the other eye.

• When the light is shone back into the abnormal eye, both pupils will get larger, even the pupil in the normal eye.

• It doesn't matter whether you start with the eye you think has the greater problem or the healthier eye: as long as the light is switched from one eye to the other and back again the signs should become apparent.

Sometimes the RAPD is obvious, as the pupil in the (most) affected eye very obviously gets larger when that eye is illuminated. But the signs can be more subtle.

Conclusion:

Why is this a good concept? (Learning With MedLife)

Teaching high-impact content, quotes from Sir William Osler and some good Neuro Draft. What more could you ask for?