Cyclorotation of the eyes and subjective visual vertical in vestibular brain stem lesions.
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Brain Stem↗
Biomedical subjects
T Brandt
Publications and source records attributed to T Brandt.
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↗
Mapping of the calpain proteolysis products of the junctional foot protein of the skeletal muscle triad junction.
The Ca2+ activated neutral protease calpain II in a concentration-dependent manner sequentially degrades the junctional foot protein (JFP) of rabbit skeletal muscle triad junctions in either the triad membrane or as the pure protein. This progression is inhibited by calmodulin. Calpain initially cleaves the 565 kDa JFP monomer into peptides of 160 and 410 kDa, which is subsequently cleaved to 70 and 340 kDa. The 340 kDa peptide is finally cleaved to 140 and 200 kDa or its further products. When the JFP was labeled in the triad membrane with the hydrophobic probe 3-(trifuoromethyl) 3-(m)[125I]iodophenyl) diazirine and then isolated and proteolysed with calpain II, the [125I] was traced from the 565 kDa parent to Mr 410 kDa and then to 340 kDa, implying that these large fragments contain the majority of the transmembrane segments. A 70-kDa fragment was also labeled with the hydrophobic probe, although weakly suggesting an additional transmembrane segment in the middle of the molecule. These transmembrane segments have been predicted to be in the C-terminal region of the JFP. Using an ALOM program, we also predict that transmembrane segments may exist in the 70 kDa fragment. The JFP has eight PEDST sequences; this finding together with the calmodulin inhibition of calpain imply that the JFP is a PEDST-type calpain substrate. Calpain usually cleaves such substrates at or near calmodulin binding sites. Assuming such sites for proteolysis, we propose that the fragments of the JFP correspond to the monomer sequence in the following order from the N-terminus: 160, 70, 140 and 200 kDa. For this model, new calmodulin sequences are predicted to exist near 160 and 225 kDa from the N-terminus. When the intact JFP was labeled with azidoATP, label appeared in the 160 and 140 kDa fragments, which according to the above model contain the GXGXXG sequences postulated as ATP binding sites. This transmembrane segment was predicted by the ALOM program. In addition, calpain and calpastatin activities remained associated with triad component organelles throughout their isolation. These findings and the existence of PEDST sequences suggest that the JFP is normally degraded by calpain in vivo and that degradation is regulated by calpastatin and calmodulin.
Adenosine Triphosphate↗
Uterine abscess after ultrasound-guided ovum retrieval in an in vitro fertilization-embryo transfer program: case report and review of the literature.
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Abscess↗
Quantification of doses to mediastinal lymph nodes in Hodgkin's disease.
Hodgkin's disease is highly curable today. Radiotherapy (RT) is the treatment of choice in the early stages. A mantle field is often used in the RT of Hodgkin's disease, and the technique and dosimetry are quite complex. We used computerized tomography (CT)-based dosimetry to determine doses delivered to different mediastinal nodes with the commonly used technique in Hodgkin's disease that was originally described by Kaplan. We used dose-volume histograms to determine doses to various groups of nodes in nine patients. Significant inhomogeneity (30%, 30%, 35%, 35%, 30%, 40%, 35%, 35%, and 30% in the nine patients) in dose distribution was found within the mediastinum. With the advent of 3-dimensional CT-based treatment planning, we are able to quantify such inhomogeneities. The question arises whether a homogeneous, lesser dose can achieve equal results. Average doses and "effective doses" were also calculated. The "effective doses" in eight patients (for a prescribed dose of 44 Gy) with a midline posterior spinal cord block added at 20 Gy were 37.3 Gy, 34.3 Gy, 36.0 Gy, 38.4 Gy, 35.8 Gy, 38.1 Gy, 36.7 Gy, and 36.7 Gy, respectively. A homogeneous dose equivalent to effective dose may achieve the same control as an inhomogeneous dose delivery. Prospective 3-D dosimetric studies are required to confirm this concept.
Hodgkin Disease↗
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↗
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↗
Otoneurology.
This review on progress in otoneurology focuses on peripheral and central vestibular disorders rather than auditory dysfunction. Recent literature reflects an imbalance between quantity and quality. For instance, several of the numerous papers on Menière's disease contribute little to furthering our knowledge of pathophysiology and treatment. The comparatively few papers on neurotransmitters, otolith function, and central vestibular pathway syndromes illustrate a promising area for scientific and clinical research in the future. Identification of vestibular pathway lesions as the cause of many oculomotor syndromes, such as downbeat and upbeat nystagmus or ocular tilt reaction lesions, will broaden the scope of otoneurology and the clinical responsibility of the neurologist.
Humans↗
Classification of vestibular brainstem disorders according to vestibulo-ocular reflex planes.
Evidence is presented for a preliminary and speculative classification of central vestibular disorders of the brain stem according to the three major planes of action of the vestibuloocular reflex (VOR). 1. Disorders of the VOR in horizontal (yaw) plane: horizontal nystagmus-vertigo; 2. Disorders of the VOR in sagittal (pitch) plane: downbeat or upbeat nystagmus-vertigo; 3. Disorders of the VOR in frontal (roll) plane: ocular tilt reaction and lateropulsion.
Brain Diseases↗
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↗
Estimation of doses to heart, coronary arteries, and spinal cord in mediastinal irradiation for Hodgkin's disease.
Early-stage Hodgkin's disease is highly curable with radiotherapy. However, radiotherapy for Hodgkin's disease is not without complications, particularly those related to irradiation of the mediastinum. In attempts to decrease complications, it is important not to compromise the results. To plan such a strategy, one needs to know the doses delivered to various volumes of normal tissues with present techniques. However, such dose-volume data do not exist. Here we demonstrate, with computerized tomography-based dosimetric techniques, such a dose-volume relationship for the heart, coronary arteries, and spinal cord. The doses were determined retrospectively in eight patients. With a prescribed dose of 44 Gy, the volumes of the heart receiving at least 22, 26, 31, 35, 40, or 44 Gy were: 77%, 75%, 70%, 57%, 33%, and 2%, respectively. The average modal doses to the coronary arteries were: anterior interventricular artery, 18.48 Gy; circumflex arterial branch, 37.84 Gy; left coronary artery, 34.76 Gy; and right coronary artery, 36.96 Gy. The average maximum spinal cord dose was 37.25 Gy. A similar prospective documentation of dose-volume relationships and correlation with (functional) long-term complications may be helpful in the development of new strategies for decreasing complications.
Coronary Vessels↗
Man in motion. Historical and clinical aspects of vestibular function. A review.
This is a review of selected aspects of the history of the vestibular system (J. E. Purkyne, E. Mach, A. Crum-Brown) and of our current understanding of vestibular malfunction in clinical vertigo syndromes. Evidence is presented for a preliminary classification of central vestibular brainstem syndromes according to the three major planes of action of the vestibulo-ocular reflex (VOR): (1) disorders of the VOR in the horizontal (yaw) plane (horizontal nystagmus, pseudo 'vestibular neuritis'); (2) disorders of the VOR in the sagittal (pitch) plane (downbeat nystagmus; upbeat nystagmus); (3) disorders of the VOR in the frontal (roll) plane (ocular tilt reaction; lateropulsion). The pathophysiology of peripheral vestibular disorders is discussed: a specific gravity differential between the cupula fluid and the endolymph (buoyancy mechanism) causes vertigo in benign paroxysmal positioning vertigo and positional alcohol nystagmus. Vestibular neuritis is probably a partial unilateral vestibular paralysis due to viral infection of the superior division of the nerve trunk. The common post-traumatic vertigo is explained by otolith dysfunction secondary to dislodged otoconia resulting in unequal loads on the macula beds and a tonus imbalance between the two otoliths.
Brain Diseases↗
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↗
Ocular tilt reaction: clinical sign of vestibular lesion.
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Eye Movements↗
[Cluster headache and chronic paroxysmal hemicrania: current therapy].
In acute attacks of cluster headache (CH), the mainstays of treatment are inhalation of pure oxygen (due to lack of any side effects), ergotamine aerosol, and intranasal application of local anaesthetics. The following treatments have hitherto been recommended for the prevention of attacks: young patient with first manifestation-methysergide; middle aged patient with episodic or chronic CH-steroids; older patient with history of resistance to therapy-lithium. These guidelines have been superceded as a result of the demonstration of the efficacy of several other drugs which have reduced side effects. This increased variety of treatments also reduces the importance of clinical differentiation between episodic and chronic cluster headache. Today, the drugs of first choice for treatment of episodic cluster headache are steroids or calcium channel blockers like verapamil, replacing methysergide which is now drug of second choice. In chronic CH, verapamil and lithium are normally prescribed, steroids-possibly in combination with one of the other drugs-are regarded as drugs of second choice. Another possibility, used with increasing frequency, is valproate acid, and the experimental drug budipine may be a further alternative in therapy resistant patients. There is no convincing role for invasive surgical procedures, particularly in the light of the increased number of effective drugs. The treatment of choice for chronic paroxysmal hemicrania is indometacin, although individual patients may respond to salicylates, naproxene, prednisone and ergotamine.
Cluster Headache↗
Influence of visual blur on object-motion detection, self-motion detection and postural balance.
We have compared the influence of visual blurring (either by use of plastic foils or by plus lenses) on detection of object-motion and self-motion, and on visual control of postural balance. Three experiments were performed--in all of which object-motion and self-motion detection latencies (response times) and postural sway (sway path) increased with increasing visual blurring. We conclude that visual blurring either by foils or by glasses affects object- and self-motion perception and postural sway in a similar way.
Attention↗
Positional and positioning vertigo and nystagmus.
Positional and positioning vertigo and nystagmus syndromes can be attributed to either peripheral or central vestibular dysfunction. The most common form is benign paroxysmal positioning vertigo which is caused by cupulolithiasis into the posterior semicircular canal. Other labyrinthine manifestations such as positional alcohol nystagmus, positional nystagmus with macroglobulinaemia and "heavy water" or glycerol ingestion occur because of a specific gravity differential between the cupula and the endolymph (buoyancy mechanism). Neurovascular compression of the vestibular nerve may be a causative factor for "disabling positional vertigo" which is an insufficiently described entity. Hesitation is highly justifiable since retromastoid craniectomy for microvascular decompression is the recommended management. Central positional vertigo is either induced by head movements which result in a transient ischaemia of the ponto-medullary brainstem, or by a change in head position relative to the gravitational vector. The latter is comprised of at least three forms: positional downbeat nystagmus (nodulus), positional nystagmus without concurrent vertigo, and positional vertigo with nystagmus. The site of the lesion is always near the fourth ventricle and the vestibular nuclei. The most probable explanation for the positional response is a vestibular tone imbalance caused by disinhibition of the vestibular reflexes on perception, eye, head and body position.
Humans↗