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Biomedical subjects

N J David

Publications and source records attributed to N J David.

At least 19 recordsLinked to original sources
PubMed2001

Innervation of the sternocleidomastoid and trapezius muscles by the accessory nucleus.

Images moving over the retina at velocities as low as a few degrees per second, in movements as head turning, can degrade visual acuity. Visual acuity requires that even minute motion of the head be compensated for, primarily via optokinetic and vestibular reflexes. Whereas we have a good understanding of some the neuronal networks involved in these reflexes, other components of this network, such as the innervation of the paired muscles that turn and tilt the head, are not as well understood. The involvement of the sternomastoid, cleidomastoid, or trapezius muscles with lesions of the cervicomedullary junction is often not in conformity with the prevailing neuroanatomic descriptions of their innervation by the accessory nuclei. We discuss evidence that: 1) the XI nucleus has a rostral and a caudal portion; 2) analogous to the VII nerve, the rostral portion receives projections from both cerebral hemispheres, whereas the caudal portion is innervated preferentially by the contralateral hemisphere; 3) the caudal XI nucleus innervates the ipsilateral cleidomastoid and trapezius with a predominantly crossed corticonuclear innervation; and 4) The rostral XI nucleus innervates both sternomastoids. Each rostral portion receives projections from both cerebral hemispheres. These anatomic features explain the seemingly discrepant findings in patients with cervicomedullary lesions.

Accessory Nerve↗
PubMed1999

Bilateral infarction in the territory of the anterior cerebral arteries.

An elderly hypertensive man had extensive bilateral infarction in the distribution of the anterior cerebral arteries. The circle of Willis was fully formed, but occlusion of the dominant anterior cerebral artery, aggravated and perhaps caused by postlaparotomy hypotension, produced the dramatic lesions, causing akinetic mutism. This stroke pattern occurs in various settings and does not require an anomalous azygous unilateral supply to both anterior cerebral arteries.

Cerebral Arteries↗
PubMed1995

Psychosis as the initial manifestation of adult-onset Niemann-Pick disease type C.

Niemann-Pick disease type C (NPC) is a neurometabolic genetic disorder that is distinguished from Niemann-Pick disease by its later onset, more insidious progression, variable visceromegaly, and abnormalities of intracellular cholesterol metabolism. We describe a patient who presented with an 8-year history of psychosis requiring chronic neuroleptic therapy for a presumed diagnosis of schizophrenia. He was subsequently diagnosed with NPC as the emerging features of dementia, ataxia, dysarthria, and vertical supranuclear ophthalmoplegia were recognized. The characteristic features of adult-onset NPC and the obstacles to early diagnosis are reviewed.

Adult↗
PubMed1989

Hemorrhage within pituitary adenomas: how often associated with pituitary apoplexy syndrome?

To determine the clinical significance and specificity of suspected intratumoral hemorrhage in pituitary adenomas, we reviewed the clinical presentations, CT results, and findings at surgery in 12 patients who had hyperintense signal within intrasellar and suprasellar masses on short TR/TE spin-echo MR pulse sequences. Eight of the cases were confirmed at surgery. In seven of the operated cases, hemorrhage was found within pituitary adenomas and in the eight case there was hemorrhage but no identifiable adenomatous tissue. Nine of the 12 patients had CT scans; three had focal areas of increased attenuation, four had focal areas of decreased attenuation, and two had uniform hypoattenuation. All nine of these CT abnormalities correlated with areas of hemorrhage on MR. Three patients had clinical apoplexy; in two there was increased attenuation on CT and in one it was decreased. We found that intratumoral hemorrhage may be seen without clinical evidence of pituitary apoplexy, and that the areas of hemorrhage can appear as low attenuation on CT. CT may be better for visualizing intratumoral hemorrhage within the first few days, but MR is more sensitive in detecting and following the hemorrhage in the subacute stage.

Adenoma↗
PubMed1989

Optokinetic nystagmus. A clinical review.

Although optokinetic nystagmus was described as a clinical phenomenon over 150 years ago, its neurophysiologic mechanism has provoked ongoing controversies and enthusiasm for its clinical application has been sporadic and tepid. In the past 15 years, improvements in clinical and experimental oculography, neuroanatomy, and single unit neuron recordings in alert animals have helped to resolve the neural circuitry of optokinetic nystagmus and to better define its clinical usefulness. The writer reviews the history of the experimental study of optokinetic nystagmus and the clinical circumstances in which this office test may be of particular value.

Brain↗
PubMed1986

The nasal junction scotoma in giant aneurysms.

Thirteen giant aneurysms in ten patients were retrospectively reviewed. Careful visual field testing of both peripheral and central fields revealed an ipsilateral nasal scotoma in 7 of the 13 aneurysms (54%), or six of the ten patients. A review of 47 giant carotid aneurysms reported in the literature revealed 16 ipsilateral nasal scotomas (34%). The more common intraocular causes of ipsilateral nasal field defects were excluded by careful funduscopic examination. In the absence of intraocular pathologic characteristics, an ipsilateral nasal junction scotoma should alert the clinician to suspect the presence of an otherwise silent internal carotid artery aneurysm.

Adult↗
PubMed1980

Pituitary apoplexy: diagnosis by computed tomography.

Computed tomography (CT) now enables the early diagnosis of pituitary apoplexy. Since CT can detect blood, it can document acute or chronic hemorrhage in pituitary adenomas. In addition, CT can discriminate between densities other than blood and can therefore be used to diagnose those cases of pituitary apoplexy in which infarction and necrosis predominate. These conclusions were verified by a review of 10 apoplectic patients studied by CT. Although nine diagnostic delays occurred tissue confirmation by surgery in eight cases and autopsy on one made us familiar with the CT findings which should be useful in future diagnosis.

Adenoma↗
PubMed1980

[Visual outcome in pituitary adenoma and supra sellar meningioma (author's transl)].

To determine factors influencing ultimate visual outcome following surgical decompression of pituitary adenoma and suprasellar meningioma, the authors analyse the post-operative visual function of 19 patients with pituitary tumors and of 11 with meningiomas encroaching upon the anterior visual pathways. Their data indicate that : visual impairment tended to be worse and of larger duration with meningiomas than with adenoma. No pre-operative data were of prognostic value for visual outcome with meningioma; for adenoma, younger age, a short duration of symptoms and transsphenoidal approach all positively influenced ultimate visual recovery. Even with minimal visual deficits, eyes tended not to recover completely.

Adenoma↗
PubMed1976

Arteriovenous malformation in the retina of a monkey.

A vascular abnormality of the retina of a rhesus monkey was studied with fluorescein angiography, microvascular examination after silicone rubber injection, and histological examination. Fluorescein angiography revealed that this abnormality was an arteriovenous shunt. Microvascular examination showed a vascular abnormality on the sclera and an end-to-end communication of the arteriovenous malformation that was a continuation of abnormally large central retinal vessels observed just before their insertion into the optic nerve in the orbit. Histologic examination proved that the arteriovenous shunt originated from the central retinal vessels in the orbit; that degeneration of the retina and the choroid was extensive near the abnormal vessels; that the abnormal vessels had normal endothelium and adventitia but remarkably widened media; and that the cavernous hamangioma-like structure in the optic disk was clearly distinguishable from a cavernous hamangioma.

Animals↗
PubMed1975

Spontaneous pneumoventriculogram following radiation of a pituitary adenoma.

Three years after radiation therapy for an intrasellar tumor, a 42-year-old housewife presented with headache, lethargy, and remarkable plain skull roentgenograms, in which dilated lateral and third ventricles were filled with air. Air apparently had entered the cranium through the sphenoid sinus and eroded sellar floor, extending directly through intrasellar remnants of the chromophobe adenoma and into the floor of the third ventricle. Frontal exploration showed an empty sella turcica and no residual tumor. She made an excellent recovery and has done well for 5 years after operative closure of the defect.

Adenoma, Chromophobe↗
PubMed1975

The effect of arterial PO2 on relative retinal blood flow in monkeys.

The relationship of blood oxygenation to retinal blood flow has been studies in rhesus monkeys. Constriction of major retinal arteries and veins during hyperoxia and dilation during hypoxia are demonstrated. Together with mean circulation times based on the technique of fluorescein densitometry curves, these data allow an estimation of retinal blood flow, which increases considerably in hypoxia and shows a moderate decrease in hyperoxia. These findings indicate that the retinal circulation parallels that of the brain in adjusting to changes in arterial PO2 with compensatory changes in blood flow.

Animals↗