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Biomedical subjects

M Dieterich

Publications and source records attributed to M Dieterich.

At least 91 records · Page 5Linked to original sources
PubMed1994

VIIIth nerve vascular compression syndrome: vestibular paroxysmia.

Neurovascular cross-compression of the root entry zone of the Vth, VIIth and IXth cranial nerves causes symptoms of trigeminal neuralgia, hemifacial spasm and glossopharyngeal neuralgia. It is reasonable to search for a group of patients presenting with typical paroxysmal vestibular and/or cochlear symptoms, analogously caused by neurovascular compression of the VIIIth cranial nerve. Since no pathognomonic sign or test has yet been established, the diagnosis of 'vestibular paroxysmia' secondary to neurovascular cross-compression is based on four characteristic features: (1) short attacks of rotational to-and-fro vertigo lasting seconds to minutes; (2) attacks frequently dependent on particular head positions and modification of the duration of the attack by changing head position ('disabling positional vertigo'); (3) hyperacusis or tinnitus permanently or during the attack; and (4) measurable auditory or vestibular deficits by neurophysiological methods. Carbamazepine is a most effective drug. In medically intractable cases, retromastoid craniotomy and microvascular decompression is a recommended procedure once the side of disorder has been identified.

Arteriovenous Malformations↗
PubMed1993

Ocular torsion and tilt of subjective visual vertical are sensitive brainstem signs.

Deviations of the position of the eye in the roll plane, ocular torsion (OT), and the subjective visual vertical (SVV) were systematically studied in 111 patients with acute vascular brainstem lesions. Of the 111 patients, 104 (94%) showed a direction-specific pathological tilt of the static SVV in our series. Seventy-one (83%) of 86 patients exhibited pathological static OT of one (47%) or both (36%) eyes. OT and SVV tilts are therefore sensitive signs in acute unilateral brainstem disorders. Measurements of SVV and OT may prove to be useful components of the neuro-ophthalmological evaluation. With respect to the directions of pathological tilt, SVV and OT are generally in the same direction. Based on neuroimaging, we conclude that all unilateral brainstem lesions caudal to the upper pons cause ipsiversive OT of one or both eyes, with concurrent ipsiversive tilts of SVV adjustments; all lesions rostral to this pontine level cause contraversive tilts of OT and SVV. Evidence is presented that pathological tilts of OT and SVV are secondary to a dysfunction of the tonic bilateral vestibular inputs that stabilize the eyes and head in normal upright position in the roll plane and dominate our perception of verticality.

Accommodation, Ocular↗
PubMed1993

Skew deviation with ocular torsion: a vestibular brainstem sign of topographic diagnostic value.

Fifty-six patients with unilateral brainstem infarctions presenting with skew deviation of the eyes were analyzed for static vestibular function in the roll plane. Ischemic lesions were allocated to the level and side of the brainstem by the clinical syndrome and neuroimaging. Two findings of clinical relevance were obtained: (1) All skew deviations were ipsiversive (ipsilateral eye was undermost) with caudal pontomedullary lesions and contraversive (contralateral eye was lowermost) with rostral pontomesencephalic lesions. (2) All skew deviations were associated with concomitant ocular torsion and tilts of subjective visual vertical toward the undermost eye. Thus, skew deviation or more correctly, ocular skew torsion is a sensitive brainstem sign of localizing and lateralizing value. Evidence is presented that the ocular skew torsion sign indicates a vestibular tone imbalance in the roll plane secondary to graviceptive pathway lesions.

Adolescent↗
PubMed1993

Cervicogenic headache: electronystagmography, perception of verticality and posturography in patients before and after C2-blockade.

Fourteen patients with cervicogenic headache (9F, 5M) with a mean age of 42.8 (29-58) years were examined, before and within two hours after unilateral anaesthetic C2-blockades, clinically as well as by means of electronystagmography, subjective visual vertical test and posturography. After C2-blockade, patients exhibited a slight gait deviation to the injected side without eye movement disorder, dysmetria or ataxia. Although in two of nine patients there was a small influence on lateral body sway on posturography, no specific pattern of abnormalities in eye-head-body coordination could be found before or after C2-blockades. Thus, there is no clinical evidence for a significant reproducible influence of the second cervical root on oculomotor or cerebellar function in cervicogenic headache. These findings confirm earlier data in animal experiments.

Adult↗
PubMed1993

Ocular torsion and perceived vertical in oculomotor, trochlear and abducens nerve palsies.

Ocular torsion (OT) and subjective visual vertical (SVV) were determined in acute and chronic oculomotor (n = 6), trochlear (n = 21) and abducens (n = 7) palsies separately for each eye in the primary position with the head upright. Ocular torsion measured by fundus photographs was not only within normal range in all abducens palsies, but unexpectedly also in 68% of third and fourth nerve palsies which involve oblique eye muscles. Pathological OT, when measurable, was slight (2 degrees - 8 degrees), monocular and occurred either in the paretic or in the nonparetic eye. Subjective visual vertical tilts were more frequent (67% of third and fourth nerve palsies) although mostly small in amplitude (1 degree - 6 degrees). They were confined either to the paretic or the nonparetic eye depending on the duration of the palsy. Determinations of SVV were always normal under binocular viewing conditions. The dissociated occurrence of OT and SVV tilts in the paretic or the nonparetic eye was dependent on the acuteness of the palsy and reflected sensory and/or motor compensation mechanisms. Third and fourth nerve palsies cause only minor and unpredictable monocular OT and SVV tilts as distinct from the frequent binocular and conjugate tilts seen in patients with acute unilateral brainstem lesions.

Abducens Nerve↗
PubMed1993

Thalamic infarctions: differential effects on vestibular function in the roll plane (35 patients).

We determined the subjective visual vertical (SVV), ocular torsion (OT), skew deviation, and lateral head tilt in 35 patients with acute thalamic infarctions (14 paramedian, 17 posterolateral, and four anterior polar) and in five patients with mesodiencephalic hemorrhages to obtain the tonic effects on vestibular function in the roll plane. Eight of 14 paramedian infarctions had complete ocular tilt reaction (OTR) with contraversive head tilt, skew deviation, OT, and SVV tilt. The OTR was due to ischemia of the rostral midbrain tegmentum, including the interstitial nucleus of Cajal (INC), and not to thalamic ischemia. Thus, the INC (and the rostral interstitial nucleus of the medial longitudinal fascicle) is the most rostral brainstem structure mediating eye-head coordination in roll. Eleven of 17 posterolateral infarctions exhibited moderate SVV tilts that were either ipsiversive or contraversive. In these 11 cases, vestibular thalamic nuclei (nucleus ventro-oralis intermedius, nucleus ventrocaudalis externus, and nucleus dorsocaudalis) were involved; infarctions in the remaining six were more ventromedial. Anterior polar infarctions did not affect vestibular function in roll.

Accommodation, Ocular↗
PubMed1993

[Neuro-ophthalmologic and posturographic studies of patients with idiopathic torticollis].

The pathophysiology of idiopathic spasmodic torticollis is still unknown. In addition to genetic and other factors, one of the possible causes under discussion is a disturbance of the vestibular system. In order to analyse vestibular influences we investigated 40 patients with idiopathic torticollis using electronystagmography, fundus photography, measurement of the subjective visual vertical and posturography. The results of the neuroophthalmological investigations and the measurement of the visual vertical were within the normal range. 53% of the patients examined showed a slight central vestibular preponderance in the electronystagmography, whereas 38% demonstrated a slight pathological monocular torsion in the fundus photography. Posturographically, there were some indications of a slightly decreased gain in visual contribution to the postural control process. None of the results could be correlated to the extent of torticollis in the individual case. We propose that these results do not confirm the hypothesis of primary vestibular lesion in the pathogenesis of torticollis. A possible explanation of the results described could be a common basic lesion which causes the torticollis on the one hand and also affects the central vestibular system on the other hand.

Adult↗
PubMed1993

Vestibular falls.

Vestibular dysfunction is a significant differential diagnosis in patients who have unexpected falls without: loss of consciousness, paresis, sensory loss, or cerebellar deficit. Either peripheral or central vestibular disorders cause postural instability with preferred directions of falling, some of which can be attributed to either the particular plane of the affected semicircular canal or a central pathway mediating the 3-dimensional vestibulo-ocular reflex in yaw, pitch, and roll. Ipsiversive falls occur in vestibular neuritis or in Wallenberg's syndrome--where they are known as lateropulsion. Contraversive falls are typical for the otolith Tullio phenomenon, vestibular epilepsy, and thalamic astasia. Predominant fore-aft instability is observed in bilateral vestibulopathy, benign paroxysmal positioning vertigo, as well as in downbeat or upbeat nystagmus syndrome. Falls can be diagonally forward (or backward) and toward or away from the side of the lesion, depending on the site of the lesion (the ocular tilt reaction is ipsiversive in medullary lesions, but contraversive in mesencephalic lesions) and on whether vestibular structures are excited or inhibited.

Accidental Falls↗
PubMed1992

Wallenberg's syndrome: lateropulsion, cyclorotation, and subjective visual vertical in thirty-six patients.

We measured the subjective visual vertical, cyclorotation of the eyes, and head and body lateropulsion in 36 patients with Wallenberg's syndrome. All patients exhibited significant tilts of the internal representation of the gravity vector, as indicated by deviation of subjective visual vertical ipsiversive to the lesion. Most patients (82%) had ipsiversive cyclorotation of one or both eyes, especially excyclotropia of the eye ipsilateral to the brainstem lesion. Twelve of 36 patients (33%), those with the most severe body lateropulsion, had a complete ocular tilt reaction consisting of head tilt, skew deviation, and cyclorotation in the roll plane. We hypothesize that deviation of subjective visual vertical, lateropulsion of the body, and cyclorotation of the eyes are the perceptual, the ocular motor, and the postural consequences of a common lesion of central vestibular pathways that subserve the vestibuloocular reflex in the roll plane. Lateropulsion in patients with Wallenberg's syndrome is interpreted as a postural consequence of an abnormal tilt of the internal representation of orientation in space.

Adult↗
PubMed1992

Neurology of otolith function. Peripheral and central disorders.

The otolith organs detect gravitoinertial forces acting on the head providing signals to the brain which are essential for spatial orientation, sensing motion and organizing motor behaviour. Although the pathophysiology of otolithic dysfunction is poorly understood, a disorder of otolith function, at a peripheral or central level, may be suspected when a patient describes symptoms of false sensations of linear motion or tilt or shows signs of specific derangements of ocular motor and postural, orienting and balancing responses. When disorientation is severe the patient may describe symptoms which sound bizarre, raising doubts over the organic basis of the disease. Our recognition of an otolithic disorder and understanding otolithic involvement in a wider neurological context may be guided by knowledge of otolith physiology and of the characteristics of the few proven otolithic syndromes.

Brain↗
PubMed1992

["Abducens neuromyotonia" with partial oculomotor paralysis].

Paroxysmal involuntary spasms of extraocular eye muscles which can lead to reversible pathological eye positions and limitations of eye movements are etiologically heterogenous. Despite the diagnostic difficulty, they are important as a neurological sign because of the usually good response to treatment. We report on a patient with the unusual combination of ocular neuromyotonia with brief paroxysmal tonic lateral deviation of the left eye and a concomitant partial third nerve palsy. The paroxysmal episodes disappeared with carbamazepine therapy. Possible pathomechanisms are discussed.

Abducens Nerve↗
PubMed1992

Cyclorotation of the eyes and the subjective visual vertical.

Pathological CR of the eyes and deviations of the SVV are among the most sensitive clinical brain stem signs. In acute unilateral brain stem infarctions, deviations of the SVV occur in 94% of cases and CR of one or both eyes is found in 88%. Deviations of CR and the SVV are typically ipsiversive with pontomedullary lesions and contraversive with pontomesencephalic lesions. They may involve a complete OTR, the triad of lateral head tilt, skew deviation and CR. There is a directional linkage between CR and the SVV (i.e. either right or left tilt), but the net tilt angles do not always match quantitatively. Pathological CR and deviations of the SVV obviously represent dysfunction of the VOR in the roll plane, which is subserved by both otolith and vertical canal inputs.

Animals↗
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↗
PubMed1991

Different types of skew deviation.

Although all manifest skew deviations appear the same for the clinician, skew deviation can result from different combinations of dysconjugate vertical ocular deviations. Evidence is presented for three different types of skew deviation when it occurs as a feature of an ocular tilt reaction. In type 1 (utricle) there is upward deviation of both eyes with different amplitudes, as described for otolith Tullio phenomenon in humans. In Type 2 (dorsolateral medulla oblongata) hypertropia of one eye occurs while the other eye remains in the primary position, the hypothetical mechanism of skew deviation in Wallenberg's syndrome. In Type 3 (midbrain tegmentum) there is simultaneous hypertropia of one eye and hypotropia of the other eye, as described for electrical stimulation of midbrain tegmentum in monkeys and observed in clinical cases with a paroxysmal ocular tilt reaction.

Brain Damage, Chronic↗
PubMed1991

The effects of baclofen and cholinergic drugs on upbeat and downbeat nystagmus.

The GABAergic drug baclofen and the cholinergic drug physostigmine were administered to patients with upbeat and downbeat nystagmus. Baclofen (orally, 5 mg three times daily) reduced nystagmus slow phase velocity and distressing oscillopsia by 25-75% in four out of five patients (two upbeat nystagmus; two downbeat nystagmus). Physostigmine (1 mg single intravenous injection) increased nystagmus in five additional patients with downbeat (1) or positional downbeat nystagmus (4) for a duration of 15-20 minutes. The different interactions of baclofen and physostigmine on neurotransmission subserving vertical vestibulo-ocular reflex could account for these effects. The response to baclofen appears to be a GABA-B-ergic effect with augmentation of the physiological inhibitory influence of the vestibulo-cerebellum on the vestibular nuclei. Similarly baclofen has an inhibitory effect on the velocity storage mechanism. Cholinergic action may cause the increment of nystagmus by physostigmine.

Adult↗