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Biomedical subjects

B T Troost

Publications and source records attributed to B T Troost.

At least 55 records · Page 3Linked to original sources
PubMed1981

Measurement of visual acuity in latent nystagmus.

A method is described for rapid and accurate assessment of visual acuity in patients with latent (occlusion) nystagmus. By using the duochrome slide of the American Optical Project-O-Chart and the green filter of the Worth red-green glasses, monocular visual acuity may be readily measured in patients with nystagmus brought out by monocular cover. The results obtained in seven patients are compared with standard opaque occlusion and occlusion with a +5.00 diopter lens.

Humans↗
PubMed1981

Variability and development of a normative data base for saccadic eye movements.

The duration, peak velocity, and acceleration of the saccadic eye movements of 13 normal subjects are plotted as functions of saccadic magnitude. The apparent peak velocity of a saccadic eye movement is sensitive to the algorithms used to calculate the velocity. The velocity channel filter should have zero phase shift and a cutoff frequency between 60 and 100 Hz in order to limit noise but pass all the signal information. Some subjects fatigue rapidly; their parameters fall outside the normal range of values.

Adult↗
PubMed1980

Upbeat nystagmus and internuclear ophthalmoplegia with brainstem glioma.

We describe the unusual association of two ocular motor abnormalities: upbeat nystagmus and internuclear ophthalmoplegia in a young woman originally believed to have demyelinating disease. Quantitative eye movement recordings documented a unidirectional defect in upward visual pursuit with preservation of the vertical vestibulo-ocular reflexes. The ocular oscillation was characterized as a type of "pursuit defect" nystagmus. An enhancing lesion of the upper brainstem seen on computerized tomography was primarily localized to the midbrain on pneumoencephalography. Biosy of the lesion disclosed a malignant glial tumor. The patient's course initally progressed but became stable following radiotherapy and chemotherapy during the next eight months. We believe the association of upbeat nystagmus and internuclear ophthalmoglegia should prompt a detailed search for a structural lesion.

Adolescent↗
PubMed1980

Intermittent downbeat nystagmus and oscillopsia reversed by suboccipital craniectomy.

We describe an unusual case of vertical oscillopsia and primary position downbeat nystagmus associated with an adult Arnold-Chiari malformation. A unique aspect of the ocular motor abnormality was the intermittent nature of the nystagmus, which displayed no relationship to head position, emotion, or the Valsalva maneuver. Conventional computed tomography with posterior fossa views was normal, but metrizamide cisternography demonstrated an extramedullary mass originally believed to be a meningioma. There was a dramatic diminution of the visual complaints and downbeat nystagmus after suboccipital craniectomy for an Arnold-Chiari malformation. Nystagmus characteristics were documented by serial quantitative eye movement recordings.

Adult↗
PubMed1980

Palinopsia: cerebral localization with computed tomography.

We report three patients whose vivid visual experiences were initially attributed to psychiatric or metabolic derangements, in the absence of obvious neurologic findings. Each depicted repetitive visual images of previously viewed objects or scenes, not necessarily confined to the region of homonymous visual deficit. Each patient had a large occipital lobe lesion, well demonstrated by computed tomography. An important diagnostic clue was documentation that the portrayed images had actually been viewed recently and therefore represented visual transpositions in time or space.

Afterimage↗
PubMed1980

Dependence of optokinetic nystagmus characteristics upon recording techniques.

The presence of infrared recording spectacles in the visual field is shown, under certain conditions, to influence human eye movement responses to optokinetic stimulation. Electrooculographic recording of optokinetic nystagmus (OKN) of the "follow" and "stare" type were made in four normal subjects, both with and without infrared spectacles. The ratio of slow phase velocity to target velocity was computed. This measure showed that wearing the spectacles produced no statistically significant change for "follow" but a significant decrement for "stare" OKN. The latter finding suggests that the advantage of more accurate eye movement recording offered by infrared spectacles should be weighed against a possible response decrement most probably caused by a stabilized image in the visual periphery.

Adolescent↗
PubMed1979

Sudden monocular visual loss in pseudotumor cerebri.

We describe a patient with papilledema due to benign intracranial hypertension who had sudden, painless monocular visual loss. Fear of further visual deterioration prompted vigorous therapeutic efforts to reduce intracranial pressure. Subsequent neuro-ophthalmologic evaluation disclosed that the visual loss was due to a subretinal neovascular membrane. Vision continued to improve after medical therapy was discontinued, and was accompanied by complete resolution of papilledema and headache. In any patient with minimal papilledema, sudden visual deterioration should initiate a search for other causes rather than zealous therapeutic efforts to reduce intracranial pressure.

Blindness↗
PubMed1979

Resolution of classic migraine after removal of an occipital lobe AVM.

A patient had a thirteen-year history of symptoms clinically indistinguishable from classic migraine: a slowly progressive visual fortification spectrum lasting 40 minutes, followed by a five- to six-hour throbbing unilateral headache with nausea and vomiting. After unsuccessful migraine therapy, investigation revealed a large occipital lobe arteriovenous malformation (AVM). Surgical removal of the AVM resulted in immediate and total resolution of all symptoms.

Adult↗
PubMed1979

Functional paralysis of horizontal gaze.

A 52-year-old steelworker displayed a consistent defect in leftward voluntary gaze across the midline. Both fast (saccadic) and slow (pursuit) eye movements were affected. Neuro-ophthalmologic evaluation revealed no additional neurologic or ophthalmologic deficit. Pupilary miosis occurred during leftward gaze attempt, indicating that the gaze palsy was due to spasm of the near reflex. Special maneuvers during clinical eye movement testing disclosed full ability to make normal horizontal fast and slow eye movements despite the apparent defect in "voluntary" leftward gaze.

Eye Movements↗
PubMed1977

The ocular motor defects in progressive supranuclear palsy.

The results of quantitative infrared horizontal eye movement recordings in 8 patients with progressive supranuclear palsy are presented. Some of the patients had total paralysis of vertical movements, but none had completely lost the ability to perform horizontal eye movements. All patients had a defect in ocular fixation previously undescribed in this condition: the universal presence of square-wave jerks. Analysis of refixation saccades demonstrated hypometria, slow velocity/amplitude relationships, and profound prolongation of duration. The pursuit abnormality, characterized clinically by "cogwheel" eye movements, represented the inability to match eye velocity to target velocity. The ratio of peak eye velocity to peak target velocity (pursuit gain) was 0.2 to 0.5. Defects in the vestibuloocular reflex included inability to increase the gain of the reflex (ratio of peak eye velocity to head velocity) during viewing of a visible, stationary target and failure to suppress the reflex when viewing a target rotating with the head.

Aged↗
PubMed1976

Dacrystic epilepsy.

We observed a 69 year old patient who had spontaneous paroxysmal attacks of weeping with lacrimation, contorted facies, and (usually) head-turning to the right. These episodes were followed by confusion and amnesia. During a pentylenetetrazol-evoked attack the EEG showed a right temporal delta rhythm. Atrophy, particularly of the right temporal regions, was noted on pneumoencephalography. We propose the term "dacrystic epilepsy" for this rare type of seizure disorder.

Aged↗
PubMed1975

Occipital lobe arteriovenous malformations. Clinical and radiologic features in 26 cases with comments on differentiation from migraine.

The differentiation of migraine headache, preceded by visual aura, from cerebral arteriovenous malformation (AVM) is often regarded as difficult. A study of 26 patients with occipital lobe AVM revealed two distinct syndromes in 18 patients--occipital epilepsy and occipital apoplexy. Occipital epilepsy is characterized either by elementary visual phenomena, such as brief flashes of light, or by dimming of a homonymous field. Occipital apoplexy results from hemorrhage and hematoma formation within the occipital lobe and is characterized by sudden headache and homonymous visual field loss. We conclude that patients harboring occipital AVMs may, indeed, have visual phenomena and headache that should not be confused with migraine because either a history of generalized seizure or bruits on examination will probably be present.

Adolescent↗