The nystagmus blockage syndrome. Congenital nystagmus, manifest latent nystagmus, or both?

We have carefully studied, by quantitative oculography, a patient with the nystagmus blockage syndrome (NBS), and two patients with a similar disorder of eye movements that might be mistaken clinically for NBS. Our recordings revealed two distinctly different abnormalities present in a single patient with NBS. Our NBS patient exhibited congenital nystagmus (CN) waveforms when viewing at distance; the CN did not damp with convergence on a near target. When the patient allowed one eye to become esotropic, however, the nystagmus damped considerably and abruptly changed from CN to manifest latent nystagmus (MLN). This peculiar transition from CN to MLN has not been described previously. The appearance of MLN in a case with ongoing CN suggests that two different mechanisms may underlie NBS, since the only other case documented with eye movement recordings showed no transition to MLN. Because the diagnosis of NBS usually is made on evidence of clinical signs alone, it is probable that these two types have been combined indiscriminately and presented as one syndrome. In addition, our discovery of two mechanisms discernable only by quantitative recording suggests that NBS has been diagnosed inappropriately in patients with clinically similar but oculographically different eye signs. Further quantitative studies are required to fully define NBS and to determine if these are the only two mechanisms found in this syndrome.

Wernicke's encephalopathy: a predictable complication of hyperemesis gravidarum

Wernicke's encephalopathy occurred during prolonged intravenous feeding in two patients with hyperemesis gravidarum. Delay in diagnosis caused a protracted illness and persisting neurologic deficits in both patients. Because of its association with chronic alcoholism, the possibility of Wernicke's encephalopathy may not be considered early enough, if at all, in other situations; it is too frequently not discovered until postmortem examination. The disease may complicate other neurologic disorders due to nutritional deficiency, but can be prevented by the timely administration of parenteral thiamine.

Downbeat nystagmus with a pseudocycloid waveform: improvement with base-out prisms

Downbeat nystagmus in primary position and oscillopsia resulted from nutritional deficiency during prolonged intravenous therapy of a patient with hyperemesis gravidarum. Wide bandwidth infrared oculography demonstrated a pseudocycloid nystagmus waveform with an increasing-velocity exponential slow phase. Because the oscillopsia decreased and the nystagmus was damped with convergence, visual acuity improved with the addition of base-out prisms to each spectacle lens.

Treatment of human spasticity with delta 9-tetrahydrocannabinol

Spasticity is a common neurologic condition in patients with multiple sclerosis, stroke, cerebral palsy or an injured spinal cord. Animal studies suggest that THC has an inhibitory effect on polysynaptic reflexes. Some spastic patients claim improvement after inhaling cannabis. We tested muscle tone, reflexes, strength and performed EMGs before and after double-blinded oral administration of either 10 or 5 mg THC or placebo. The blinded examiner correctly identified the trials in which the patients received THC in seven of nine cases. For the group, 10 mg THC significantly reduced spasticity by clinical measurement (P less than 0.01). Quadriceps EMG interference pattern was reduced in those four patients with primarily extensor spasticity. THC was administered to eight other patients with spasticity and other CNS lesions. Responses varied, but benefit was seen in three of three patients with "tonic spasms." No benefit was noted in patients with cerebellar disease.

Ischemic optic neuropathy as a possible early complication of vascular hypertension

Eighteen patients with idiopathic optic neuropathy lacked symptoms and signs of cardiovascular and cerebrovascular disease, especially when compared to three groups of patients with sudden visual loss caused by retinal infarction, transient ischemia, and cerebral infarction. Many patients in the latter groups had hypertension, carotid bruits, heart disease, transient ischemic attack, and stroke. But among the patients with ischemic optic neuropathy, hypertension was the only evidence of cardiovascular disease, affecting 44% of the patients. We argue that, in many cases, ischemic optic neuropathy represents a direct and early complication of hypertension arterial disease affecting small arterioles supplying the anterior part of the optic nerve. The pathologic process may thus be similar or identical to lacunar infarction of the brain.

Electrical correlates of normal binocular vision

Several characteristics of the visual stimulus determine the waveform of the visually evoked potential (VEP). Many of them must be controlled for the most efficient application of this technique as a clinical diagnostic test. We describe a simple system that demonstrates the effects of the VEP of adding structure to the stimulus, varying the size and clarity of its pattern elements, and presenting an image to the eye opposite the stimulated eye. We identify wave components of the VEP generated by a flashed pattern that reliably reflect each of these changes in stimulus properties.

Papillophlebitis: benign retinopathy resembling papilledema or papillitis

Three young adult patients are described to illustrate an uncommon syndrome, papillophlebitis. This entity, characterized by mild but protracted monocular visual impairment, edema of the optic disc, retinal venous engorgement, and perivenous retinal hemorrhages, resembles atherosclerotic occlusion of the central retinal vein in older patients. In younger individuals it is benign and self limited, but may be incorrectly diagnosed as optic neuritis or papilledema. These alternatives can usually be excluded if tests of visual function do not indicate an optic nerve conduction defect and if the clinical presentation and examination of the opposite ocular fundus do not disclose evidence of increased intracranial pressure. Because resolution usually occurs spontaneously, immediate neuroroentgenographic tests may be inappropriate. Effective treatment has not been established; local instillation of corticosteroids may hasten recovery.

The visually evoked potential in Huntington disease

The visually evoked potential was abnormal in 17 of 18 patients with Huntington disease. Both early and late wave components were affected, and the averaged amplitude for the patients was reduced in comparison with 50 normal control subjects. Despite striking attenuation and disorganization of the complex, latency of initial wave components was normal. The abnormality was not present in patients with a variety of other nonfocal cerebral disorders nor in 13 children of patients with Huntington disease.

Perioptic meningiomas. Syndrome of long-standing visual loss, pale disk edema, and optociliary veins

Three patients had a syndrome of progressive or long-standing visual loss, pale disk edema, and optociliary veins, indicating that a spheno-orbital meningioma had invaded the anterior perioptic meninges. To diagnose this syndrome, one must distinguish "disk edema" from "papilledema"; although both result from increased pressure within the perioptic subarachnoid space, disk edema is caused by a variety of lesions just behind the globe, whereas papilledema is caused by remote lesions that raise intracranial pressure. Optociliary veins reflect the slowness of progression of both processes. This ophthalmoscopic diagnosis carries important implications, namely, that the tumor grows very slowly and that surgical treatment will not improve vision. Therefore, excision may not be the treatment of choice.