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Biomedical subjects

T Lempert

Publications and source records attributed to T Lempert.

At least 19 recordsLinked to original sources
PubMed1997

Selective vestibular damage in neurosarcoidosis.

We report a patient with neurosarcoidosis who developed bilateral benign paroxysmal positional vertigo (BPPV) of the posterior canals, deafness, and absent responses to conventional caloric and rotational vestibular testing. Additional rotation in the planes of the vertical semicircular canals revealed relative sparing of vertical canal function. This vertical-horizontal canal dissociation explains the presence of BPPV and suggests that the vestibular damage in this patient is secondary to a vasculitic neuropathy.

Adult↗
PubMed1997

Effect of otolith dysfunction. Impairment of visual acuity during linear head motion in labyrinthine defective subjects.

Visual symptoms emerging after the loss of vestibular function are usually attributed to the dysfunction of semicircular canal vestibulo-ocular reflexes, as they have been shown to stabilize vision during angular head movements. However, natural head displacements involve both angular and linear motion, and therefore visual instability may occur because of defective otolith-ocular reflexes (OORs) which are the eye movements evoked by linear head acceleration. In this paper, the relationship between OORs and visual acuity during linear head motion was studied in normal subjects and 14 patients with bilateral loss of caloric responses. OORs were elicited in darkness by step acceleration (0.24 g) of the whole body along the interaural axis. Latency, slow phase velocity and asymmetry of the OOR were measured from the desaccaded and averaged electrooculographic trace. Visual acuity was assessed during sinusoidal lateral oscillation of the subject viewing an earth-fixed target, and vice versa with the subject stationary and the target moving at 0.5, 1.0 and 1.5 Hz. The task was to recognize numbers flashing up on a three digit light-emitting diode visual display. Normal subjects had symmetrical OORs with short latencies (< 130 ms). In patients, OORs were either absent (n = 2) or abnormal with asymmetries (n = 8), diminished velocities (n = 4) or prolonged latencies (n = 6). At high frequency oscillation (1.5 Hz), normal subjects invariably recognized more numbers during self-motion compared with target motion, whereas most patients did not. In patients, abnormal dynamic visual acuity was correlated with absent or delayed OOR responses. This is the first demonstration of a functional role of the OORs in that they contribute to visual stabilization during high frequency linear head motion. Bilateral vestibular failure commonly affects the OORs and thereby compromises dynamic visual acuity.

Acceleration↗
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↗