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Biomedical subjects

T Lempert

Publications and source records attributed to T Lempert.

At least 55 records · Page 3Linked to original sources
PubMed1996

Transaural linear vestibulo-ocular reflexes from a single utricle.

To clarify the directional sensitivity of a single utricle with respect to the transaural linear vestibulo-ocular reflex (L-VOR) we studied seven patients before and after vestibular neurectomy. Patients were seated upright in an electrically powered car running on a linear track. Transaural acceleration steps of 0.24 g were applied randomly to the left and right in the dark. The slow phase velocity of the L-VOR was measured from the average of the induced compensatory eye movements. L-VOR asymmetry was calculated as (R-L/R + L x 100) and is < 13% in normals. Before surgery, responses were mostly symmetrical. One week after surgery, however, all patients had diminished or absent responses with medial acceleration of the remaining utricle. Asymmetries averaged 65% after correction for spontaneous nystagmus. Our findings indicate that afferents for the L-VOR originate from the lateral region of the macula where hair cells with ipsilateral on-directions are located.

Eye↗
PubMed1996

A positional maneuver for treatment of horizontal-canal benign positional vertigo.

Horizontal-canal benign positional vertigo (HC-BPV) is characterized by brief attacks of intense vertigo that are induced by mainly rolling over in bed. Examination shows a burst of purely horizontal nystagmus beating toward the undermost ear when the head is turned from supine to either lateral position. Two patients with typical HC-BPV were treated by a new positional procedure that aims to clear particles from the affected canal. The maneuver starts with the patient in the supine position and consists of three 90-degree head rotations toward the unaffected ear. Both patients had immediate and sustained relief of their attacks. No positional nystagmus could be elicited after the maneuver. The rapid cessation of positional vertigo and nystagmus adds evidence that HC-BPV is caused by dense particles that move within the canal whenever its orientation toward gravity is changed.

Female↗
PubMed1996

Recognizing syncope: pitfalls and surprises.

Loss of consciousness and falling are the key features of syncope. Common accompaniments include tonic and myoclonic muscle activity, eye deviations, automatisms, vocalizations and hallucinations which may render the distinction from epileptic seizures difficult. Differential diagnosis is based on the specific features and not the mere presence of these phenomena. Recognition of syncope depends also on accurate information about precipitants, premonitory symptoms and postictal events: the absence of postictal confusion has been identified as the single most powerful factor discriminating syncope from epileptic seizures whereas incontinence and head injury are common in both conditions. Investigations such as electroencephalogram, tilt testing and postictal prolactin or creatine kinase levels may be helpful but are never diagnostic in isolation. Exceptionally, hypoxic and epileptic mechanisms interact within a single attack.

Automatism↗
PubMed1996

The eye movements of syncope.

We videotaped the eye movements of syncope in 25 healthy volunteers who induced fainting by hyperventilation and Valsalva maneuver on a tilt table. In an additional three subjects, syncope was similarly induced during horizontal sinusoidal oscillation on a rotating chair while eye movements were recorded by electro-oculogram. Fourteen of 25 subjects experienced syncope on the tilt table. Six had downbeat nystagmus (DBN) at the onset that evolved into upward eye deviation, whereas seven showed isolated tonic upward deviation. In one subject the eyes remained in primary position. The gain of the vestibulo-ocular reflex (VOR) increased by 65% on average during syncope with concurrent vestibular stimulation. DBN, upward eye deviation, and increased VOR gain may all be caused by vestibular disinhibition caused by cerebellar hypoperfusion.

Adult↗
PubMed1995

[Clinical variants of pseudotumor cerebri syndrome].

Increased cerebrospinal fluid pressure of usually unknown etiology is called pseudotumor cerebri. The key symptoms are headache, papilledema and fluctuating visual disturbances. Six cases are presented to illustrate the clinical variability of this syndrome. Headache or papilledema may be missing in individual cases. The clinical diagnosis can be facilitated by the recognition of accessory signs and symptoms, such as VIth nerve palsy, tinnitus and other cranial nerve disorders or neck stiffness. For the therapeutic outcome it is essential to detect and monitor visual disturbances early in the course of the disease.

Adult↗
PubMed1994

Syncope: a videometric analysis of 56 episodes of transient cerebral hypoxia.

To investigate the clinical features of transient cerebral hypoxia, syncope was induced in 56 of 59 healthy volunteers through a sequence of hyperventilation, orthostasis, and Valsalva maneuver. All events were monitored on video by two cameras. Complete syncope with falling and loss of consciousness was observed in 42 subjects, lasting 12.1 +/- 4.4 seconds. Myoclonic activity occurred in 38 of these 42 episodes (90%). The predominant movement pattern consisted of multifocal arrhythmic jerks both in proximal and distal muscles. Superposition of generalized myoclonus was common. Additional movements such as head turns, oral automatisms, and righting movements occurred in 79%. Eyes remained open throughout syncope in most subjects and initial upward deviation was common. Sixty percent reported visual and auditory hallucinations. Thirteen subjects had incomplete syncope with falls but partially preserved consciousness. These episodes were shorter and usually not accompanied by myoclonus and hallucinations. Transient amnesia and unresponsiveness without falling occurred in 1 subject.

Adult↗
PubMed1993

[Migraine: differential diagnosis in episodic vertigo].

Vestibular symptoms can be the predominant feature of migraine both in children and adults. Attacks of spontaneous or positional vertigo lasting from minutes to days may occur with or without concomitant headache. In the literature three syndromes of vestibular migraine have evolved: basilar artery migraine, benign recurrent vertigo and benign recurrent vertigo of childhood. In clinical practice, however, variants seem to be more frequent than the pure syndromes. Diagnosis is based on the individual constellation of typical precipitants and symptoms of migraine and the efficacy of pharmacological migraine prophylaxis. Nine cases are presented.

Adult↗
PubMed1992

Evolution of white matter lesions in neurofibromatosis type 1: MR findings.

To characterize further the evolution of white matter lesions in neurofibromatosis type 1, we reviewed 68 MR images in 43 patients (age, 1-31 years), including 25 follow-up studies (mean interval, 27 months). Lesion number, location, morphology, signal characteristics, and contrast enhancement were assessed. Lesion characteristics and changes thereof were correlated with the patients' ages. Thirty-four patients (79%) had white matter lesions. These lesions were hyperintense on T2-weighted images, were isointense on T1-weighted images, and showed no mass effect or contrast enhancement in 31 patients; in three patients, T1-prolongation was observed (one with significant mass effect). None of the lesions evolved into a glioma. The most common locations were the cerebellum (49%), brainstem (22%), and internal capsule (19%). Nineteen patients had white matter lesions and follow-up studies. Lesions decreased in size or number in seven patients (average age, 13 years), showed no change in three (average age, 12 years), increased in size or number in four (average age, 5 years), and showed a mixed pattern (increased/decreased size/number) in four (average age, 7 years). White matter lesions in neurofibromatosis type 1 frequently increase in size or number early in childhood; this did not indicate neoplasia in our study. The lesions tend to resolve with increasing age. Lesion progression in a child more than 10 years old warrants close follow-up to rule out a neoplasm.

Adolescent↗
PubMed1991

How to identify psychogenic disorders of stance and gait. A video study in 37 patients.

Thirty-seven patients with psychogenic disorders of stance and gait were clinically evaluated, recorded on video, and analysed with regard to clinical phenomenology. Characteristic, suggestive and unspecific features were identified. Six characteristic features proved most valuable for diagnosis of psychogenesis, as they occurred alone or in combination in 97% of patients: (1) momentary fluctuations of stance and gait, often in response to suggestion; (2) excessive slowness or hesitation of locomotion incompatible with neurological disease; (3) "psychogenic" Romberg test with a build-up of sway amplitudes after a silent latency or with improvement by distraction; (4) uneconomic postures with wastage of muscular energy; (5) the "walking on ice" gait pattern, which is characterized by small cautious steps with fixed ankle joints; (6) sudden buckling of the knees, usually without falls. Seventy-three percent of patients had additional suggestive features. Classification into characteristic subtypes was not found useful because predominant features varied from patient to patient and occurred in various combinations. Factitious impairment of stance and gait was studied in 13 healthy drama students. Simulated gait dysfunction appeared less conspicuous and more difficult to diagnose than the clinical psychogenic disorders.

Adult↗
PubMed1990

Natural history and outcome of psychogenic seizures: a clinical study in 50 patients.

The natural history and the outcome of psychogenic seizures was studied in 50 patients by retrospective analysis and follow-up after a mean of 2 years. Concomitant epilepsy was definite in only 8% and possible in 14%, while 50% took anticonvulsants. Overall, 66% of patients showed heterogeneous psychiatric abnormalities, most commonly a depressive syndrome (24%), whereas hysterical personality features were rare (8%). Forty-two percent of patients were unemployed. Follow-up of 41 patients (82%) showed that 34% had become seizure free. Outcome was poor in those with a long history of psychogenic seizures and pathological psychiatric findings. In contrast, almost all patients with recent onset of psychogenic seizures and normal psychological status had become seizure free. At follow-up, 56% of patients were found to be in a poor or very poor state, which resulted from a combination of physical, psychic and social problems in most cases.

Adolescent↗
PubMed1990

Psychogenic disorders in neurology: frequency and clinical spectrum.

Among 4470 consecutive neurological inpatients presenting "with typical neurological symptoms" 405 (9%) were found to have psychogenic rather than neurological dysfunction of the nervous system as the primary cause of admission. This probably represents a conservative figure, since secondary and minor pseudoneurological symptoms were not included. Retrospective analysis of these cases showed that pain was the most common psychogenic symptom, followed by motor symptoms (in particular stance and gait disturbances), dizziness, psychogenic seizures, sensory symptoms, and visual dysfunction. Unilateral motor and sensory symptoms were equally distributed to the left and right side of the body. Psychiatric abnormalities in these patients were heterogenous. Depressive syndromes were most common (38%), whereas hysterical features were less frequent than expected (9%). On discharge, improvement was significantly better for patients with recent onset of symptoms (2 weeks or less) than for those with longstanding disturbances. Short-term outcome was best for motor symptoms and worst for pain. Improvement was independent of psychiatric findings, coexistence of a neurological disease, age, and sex.

Adult↗