Posterior scleritis--an unusual manifestation of Cogan's syndrome.

Cogan's syndrome is characterized by a non-luetic interstitial keratitis associated with vertigo, tinnitus and profound deafness. Evidence of a systemic vasculitis is found in up to 50% of patients. Atypical forms of Cogan's syndrome have been described in which the ocular inflammatory disease may be more severe. We describe a case of atypical Cogan's syndrome in association with bilateral posterior scleritis. Serial B-scan ultrasound measurements of posterior scleral thickness were found to be useful in assessing disease activity, in combination with clinical findings. Combination therapy with prednisolone and cyclosporin controlled the ocular disease but the deafness was irreversible. The length of follow-up of this case highlights the frequent relapses and difficult management problems which may be faced. This multisystem disease requires the close co-operation of ophthalmologist, physician and otorhinolaryngologist. Aggressive therapeutic intervention with high-dose combined immunosuppressive agents may be necessary to control severe ocular inflammatory disease.

Optic neuritis. Differential losses of luminance and chromatic function near a scotoma.

Visual sensitivity to achromatic and chromatic stimulus flashes was determined at sites just inside, on the boundary and just outside scotomata in 11 patients with recovered optic neuritis. The colour of the flashes and the size of the steady background on which they appeared were such that detection was more likely to be mediated by either the large-diameter, magnocellular fibres or the small-diameter, parvocellular fibres of the anterior visual pathway. The spacing of the test sites ranged from 0.5 degrees to 4 degrees visual angle, depending on the shape and location of the scotomata. The greatest differences in sensitivity were between sites just inside and just outside the scotoma and in response to achromatic stimuli more likely to involve the magnocellular fibres. This effect may be due to the size of magnocellular fibres or to their relatively smaller numbers.

Sensory loss in syringomyelia: not necessarily dissociated.

The pattern of sensory loss was assessed in 210 cases of syringomyelia. Dissociated sensory loss occurred in 49% of cases, indicating that its occurrence is not a necessary finding for the diagnosis of syringomyelia. Syringomyelia should be considered in the differential diagnosis of all cases of spinal cord disease.

Abnormalities of visual function in hereditary motor and sensory neuropathy.

Visual function was studied in a group of 15 patients with hereditary motor and sensory neuropathy (HMSN). Psychophysical measures of luminance and chromatic threshold and temporal contrast sensitivity were undertaken, together with visual evoked potentials (VEPs), visual fields and clinical neuro-ophthalmological examination. A patchy loss of visual function was found in individual cases of HMSN. In the group analysis there was evidence of a selective loss of luminance threshold and temporal contrast sensitivity at low temporal frequencies; the VEP P100 latency was not significantly prolonged. The losses of visual function in HMSN were discussed and compared with visual losses in multiple sclerosis, which had been detected using identical experimental techniques.

Visual loss in multiple sclerosis and its relation to previous optic neuritis, disease duration and clinical classification.

Visual function was investigated in a group of 58 clinically classified cases of multiple sclerosis (MS). Psychophysical measures of luminance and chromatic threshold sensitivity and temporal contrast sensitivity were undertaken, together with visual evoked potentials and Bjerrum screen perimetry. The patient group was divided on the basis of optic neuritis (ON), clinical disease duration and clinical classification. A comparison of the results of all visual measures suggested a nonuniform loss of function in the patient group without ON and a more consistent loss of function in the group with ON. The various measures were equally efficient in detecting abnormal function, albeit from different areas of the central visual field. Clinical disease duration was not a significant independent factor in predicting visual dysfunction. In contrast, a comparison of clinical classification categories revealed significantly fewer abnormalities of visual function in the suspected MS category (31%) than in the ON, early probably and clinically definite categories (75-100%), a result which indicated the importance of clinical classification as a predictor of visual dysfunction.

Optic neuritis: variations in temporal modulation sensitivity with retinal eccentricity.

Temporal modulation sensitivity functions were measured centrally and at eccentricities of 2.5 degrees, 5 degrees and 10 degrees in the temporal visual field of 12 patients with recovered optic neuritis and in a group of matched normal controls. A circular, spatially uniform stimulus of 1 degree angular subtense was presented with sinusoidal modulation at 5, 8, 14 and 23 Hz. The general pattern of results in patients was a loss of sensitivity relative to normal controls at all temporal frequencies at 0 degree and 2.5 degrees eccentricity, with rather greater losses occurring at the medium-to-lower temporal frequencies. At 5 degrees eccentricity, the losses were confined to medium temporal frequencies only, and at 10 degrees eccentricity there was no significant loss at any temporal frequency. These findings may be explained by a greater vulnerability of optic nerve fibers of small diameters to the effects of demyelinating disease.

Fibrinolytic activity after subarachnoid haemorrhage and the effect of tranexamic acid.

Seventy-four patients with recent subarachnoid haemorrhage were randomly allocated to placebo or tranexamic acid treatment. Fibrinolytic activity in the blood and cerebrospinal fluid was assessed before treatment, one week later and two weeks later. The natural history of fibrinolysis following subarachnoid haemorrhage was obtained from analysis of the placebo group. Following subarachnoid haemorrhage, fibrin degradation products and plasminogen activity in the cerebrospinal fluid were elevated. Subsequently, fibrin degradation products in the cerebrospinal fluid fell progressively over the following 2 weeks. Changes in cerebrospinal fluid plasminogen activity correlated with those of blood plasminogen activity. Complications such as rebleeding, hydrocephalus or cerebral thrombosis could not be predicted from analysis of fibrinolytic activity. Tranexamic acid treatment resulted in a reduction in cerebrospinal fluid and blood plasminogen activity. The relevance of fibrinolysis in cerebrospinal fluid and blood to the management of subarachnoid haemorrhage is discussed.

Paradoxical effects of temperature in multiple sclerosis.

Six cases of multiple sclerosis are reported in which cold produced a temporary exacerbation of symptoms and signs of the disease. Also, in one case investigated in detail by psychophysical methods, heating produced a paradoxical deterioration in vision and simultaneous improvement in sensory and motor function. The effect of temperature in multiple sclerosis is discussed and a physiological explanation for the paradoxical response to heating is suggested.

Familial subependymomas.

A family of eleven siblings is presented, five of whom developed a brain tumour. Three siblings had a subependymoma, one had an ependymoma and in one case the tumour was unverified histologically. The significance of familial brain tumours is discussed.