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Biomedical subjects

M W ten Hove

Publications and source records attributed to M W ten Hove.

5 recordsLinked to original sources
PubMed2004

Rotational acceleration measurements--evaluating helmet protection.

PURPOSE: Current helmet testing standards do not address the rotational components of an impact to the head. We describe a new testing paradigm used to measure the rotational acceleration of a headform and a protective helmet following an impact to the head in the horizontal plane. This impact simulation allows for the testing of currently available head protection devices in conditions thought to be important for the generation of cerebral concussion. The degree to which a particular helmet dampens rotational acceleration, and thus protects against concussion, can be assessed. METHODS: Our testing device consists of a pneumatic piston that provides a measured impact to a standard headform. Four different helmets were tested using the described paradigm. RESULTS: Acceleration curves for each helmet and the corresponding headform are presented. CONCLUSIONS: Clear differences in rotational acceleration were demonstrated. Possible avenues of further investigation are discussed.

Acceleration↗
PubMed1998

Foveal cone dysfunction syndrome.

Our objective was to describe and expand the clinical spectrum of a rarely detected, previously reported photoreceptor disorder restricted to the foveal cones. Three patients with bilaterally decreased acuity and hemeralopia were examined to exclude a structural, vascular, inflammatory, or degenerative process. Each patient underwent a full neuroophthalmic examination, including full-field and focal cone electroretinogram (ERG). All three patients had normal-appearing fundi, mild dyschromatopsia, central or paracentral visual field depressions, normal full-field photopic and scotopic ERGs, and markedly reduced focal, foveal cone ERG responses. One patient had a ring scotoma and an asymptomatic family member with abnormal full-field and focal cone ERG. The syndrome of acquired foveal cone dysfunction presents as a bilateral, painless, progressive central visual loss with minimal or absent fundus changes. It eludes diagnosis until focal, foveal cone ERG is performed.

Aged↗
PubMed1997

Occult perineural tumor infiltration of the trigeminal nerve. Diagnostic considerations.

Cutaneous carcinomas of the face, and some nasopharyngeal carcinomas, may present with facial dysesthesias and/or facial nerve palsies in the absence of visible masses. Even with frank ophthalmoplegia, occult tumors that present in this matter may elude detection, for which reason specific diagnostic studies must be employed. We report seven cases of trigeminal nerve infiltration by occult tumors (five squamous cell carcinomas, one basal cell carcinoma, and one adenoid cystic carcinoma), and outline the clinical course, diagnostic investigations, and the subsequent management of these patients. The importance of establishing an early diagnosis before the tumor has transgressed the basal foramina is emphasized, as tumor infiltration of the cavernous sinus carries a more guarded prognosis. The use of magnetic resonance imaging to identify involved peripheral nerve branches that may then be biopsied is suggested. The patho-physiological mechanisms of neurotropic spread of tumor are reviewed.

Aged↗
PubMed1997

Interobserver agreement in the evaluation of acute retinal artery occlusion.

OBJECTIVE: To determine the agreement between two ophthalmologists in the evaluation of two important funduscopic features related to acute retinal artery occlusion: retinal cloudy swelling and visible retinal emboli. DESIGN: An interobserver variability study in which two ophthalmologists (one trained in glaucoma, the other in neuro-ophthalmology) independently viewed fundus photographs and categorized them with respect to the presence or absence of cloudy swelling and retinal emboli. Inter- and intraobserver agreement was calculated with the kappa statistic. SETTING: Retina service at a university-affiliated hospital in Kingston, Ont. PATIENTS: The fundus photographs of 102 patients were included: 60 with acute retinal artery occlusion, 30 with conditions mimicking acute retinal artery occlusion and 12 healthy patients. RESULTS: Both interobserver and intraobserver agreement as to the presence of retinal cloudy swelling were very high (kappa = 0.835 and 0.866 respectively). More variability was seen for the presence of retinal emboli, but, overall, interobserver and intraobserver agreement were still high (kappa = 0.726 and 0.629 respectively). CONCLUSIONS: Our results suggest that clinicians use similar visual clues to categorize fundi with respect to retinal cloudy swelling and visible retinal emboli.

Acute Disease↗