Congenital-type nystagmus emerging in later life.

We describe six patients who, as teenagers or adults, developed florid nystagmus with consequent visual symptoms without any other manifestation of disease. In three patients, previous ophthalmologic examination had excluded nystagmus, and there was medically informed witness to its onset. The remainder may or may not have had a milder, unsuspected nystagmus before the development of symptoms. Ophthalmologic and neurologic investigations were negative, and follow-up of 2 to 15 years has been uneventful. Eye movement recordings showed the characteristics of the nystagmus to be indistinguishable from congenital nystagmus, which normally becomes manifest in early infancy. We conclude that a congenital-type nystagmus can emerge or enhance in later life without apparent provocation and is probably associated with a benign pathophysiology.

Motorist's vestibular disorientation syndrome.

Six patients are described who experienced difficulty in driving a motor car. Four had illusions that the car was turning, which occurred particularly on open, featureless roads or the brows of hills and caused the driver to stop. All patients had peripheral or central neurootological abnormalities, but the only finding consistent with the directionality of the symptoms was an unpleasantly increased sense of circularvection during optokinetic stimulation in the direction of the illusion. These problems occur because of a false sense of orientation arising either from inappropriate signals from disordered vestibular canal and otolith organs or from a disordered central interpretation of vestibular information, and become manifest in the absence of adequate visual stabilisation. The other two patients with lateralised vestibular disease made inappropriate steering adjustments in the direction of the imbalance of vestibular tone.

Neurological evidence for dissociation of pursuit and optokinetic systems.

Patients with neurological disease were examined for dissociations between the performance capabilities of pursuit, immediate onset passive and active optokinetic responses to determine whether these functions are subserved by separate mechanisms. We found a patient in whom pursuit was intact in the presence of severely impaired optokinetic responses and another in whom optokinetic responses were intact in the presence of severely deranged pursuit. These dissociations suggest that pursuit and immediate onset optokinetic responses are mediated, to some extent, by separate mechanisms as the results are not explicable in terms of a continuum of performance ability related to target size. Another patient, who had virtually no pursuit or passive optokinetic responses, produced high slow phase velocities of active optokinetic response, which demonstrates that the active form of optokinetic response can be more than a linear addition of pursuit and passive optokinetic responses.

Assessment of vestibulo-ocular reflexes in congenital nystagmus.

The vestibulo-ocular reflex and its suppression by fixation of a target rotating with the subject were tested in 18 subjects with congenital nystagmus using steps of constant velocity rotation and sinusoidal stimuli swept in frequency between 0.01 and 1.0 Hz. Responses to stopping stimuli were abnormal in waveform and of short duration in most subjects tested. This pattern was attributed to masking of the response by spontaneous eye movements and to adaptation. In contrast, during both oscillation in the dark and attempted suppression of the vestibulo-ocular reflex, all subjects had nystagmus that was modulated with the stimulus during all frequencies of stimulation. The phase relationship of the nystagmus to the motion stimulus was the same as in normal subjects. Estimates of the gain of the vestibulo-ocular reflex response were not meaningful because of contamination of the vestibular response by the congenital nystagmus waveforms. Modulation of amplitude and reversal of nystagmus in phase with the vestibular stimulus at all frequencies of oscillation were shown most clearly during attempted suppression of the vestibulo-ocular reflex. This finding is clinically useful because it establishes suppression as a test of the presence of vestibular function in congenital nystagmus.

Factors affecting visual loss in benign intracranial hypertension.

Visual function and optic disc appearances were studied in 68 patients conforming to established criteria of benign intracranial hypertension (BIH). The clinical, radiological, and laboratory findings of those patients whose visual field or acuity deteriorated were compared with those who did not deteriorate over an average follow-up of 4.1 years. Definite loss of visual function occurred in 49% of eyes and was severe in 6%. Patients with high grade or atrophic papilledema, or peripapillary subretinal hemorrhage, were significantly more likely to have had deterioration of visual function. Transient obscurations of vision and the presence of optico-ciliary shunts were associated with severe visual loss. Anemia, older age, and high myopia were other risk factors for visual loss. Chronic papilledema may cause progressive visual loss and, for this reason, BIH is not a benign condition; fundal changes and visual function should be carefully monitored.

Bilateral central scotomata due to intracranial tumour.

Bilateral centrocaecal scotomata have been recognised as a sign of intrinsic optic nerve disease, usually associated with hereditary optic neuropathy, and nutritional or toxic amblyopias. This report describes four patients with central scotomata due to intracranial masses, three of whom recovered after surgical intervention. The clinician should be alerted to the association in patients with headaches, other neurological signs, and central visual loss.

Critical perfusion of brain and retina.

Four patients with extensive occlusive disease of the extracranial arteries are described. All suffered attacks of visual loss due to transient retinal ischaemia and all developed the haemorrhagic changes of low-flow retinopathy. Resting cerebral blood flow was within normal limits in all patients. The attacks were provoked by falls in systemic blood pressure or, in one patient, by facial heating. The probable mechanism in this last case is thought to be diversion of blood to a dilated external carotid vascular bed. Temporary cerebral and brachial symptoms occurred but no permanent changes developed. Successful surgical reconstruction was achieved in two patients with relief of symptoms.

A comparison of phenytoin and pheneturide in patients with epilepsy: a double-blind cross-over trial.

A double-blind cross-over trial between pheneturide and phenytoin in ninety-four outpatients with epilepsy is described. There was no significant difference between the frequency of seizures in the two groups. The difficulties in comparing two anticonvulsants of similar efficacy are discussed particularly in relation to ethical problems, the selection of patients and trial design.

Auditory evoked phosphenes in optic nerve disease.

Five patients with optic neuropathy, four vascular and one demyelinating, are described who each complained of an unusual symptom. Bright flashes of light (phosphenes) occurred in the affected eyes and were evoked by sudden unexpected sounds. Movement of the eye alone did not reproduce the symptom. In all patients the phenomenon was sufficiently prominent to interfere with sleep and was the main complaint of one patient. An anticonvulsant (phenytoin) greatly reduced the frequency and intensity of the phosphene in one patient.

Vertical supranuclear gaze palsy with secondary syphilis.

A 48-year-old man presented with a vertical gaze palsy associated with secondary syphilis. It is suggested that the eye movement disorder is due to syphilitic endarteritis in the mesodiencephalic region.

Ocular changes in limited forms of Wegener's granulomatosis.

Eight patients who had limited forms of Wegener's granulomatosis are described, with details of their pathology. Ocular pathological data were available for 2 of them. The condition carries a serious ocular risk; useful vision was lost in 6 out of 16 eyes (37%). An indolent but slowly progressive marginal keratitis and scleritis was a prominent feature in 4 patients and was helpful in suggesting the diagnosis. Limited froms of Wegener's granulomatosis carry a better prognosis and response to treatment than the classical disease.

Heredopathia atactica polyneuritiformis (Refsum's disease): 1. Clinical features and dietary management.

In a patient with Refsum's disease successful dietary control of the disease has been shown to depend on adequate energy and protein intake from phytanic acid-free sources and restriction of dietary phytanic acid to a maximum of 10 mg per day, with the provision of a generous amount of the essential fatty acid, linoleic acid. The present work gives data on the phytanic-acid content of various foodstuffs and suggests dietary manipulation of the patient. Although the role that chlorophyll-bound phytol plays in Refsum's disease is uncertain, it is advisable that this is eliminated until its role is more clearly identified.

Heredopathia atactica polyneuritiformis (Refsum's disease): 2. Estimation of phytanic acid in foods.

Estimation of phytanic acid in human plasma and in a number of foodstuffs is described.

Heredopathia atactica polyneuritiformis (refsum's disease) treated by diet and plasma-exchange.

A patient with severe heredopathia atactica polyneuritiformis (Refsum's disease) has responded well to treatment by large-volume plasma-exchange. The dietary control of the disease has been shown to depend not only on a diet low in phytanic acid, but also on one high in calories, which prevents mobilisation of phytanic acid from fat stores.