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H Mühlendyck

Publications and source records attributed to H Mühlendyck.

At least 19 recordsLinked to original sources
PubMed1995

[Indications and methods of surgical treatment in congenital nystagmus].

The authors present methods of operation performed in different types of congenital nystagmus in which the amplitude and frequency of nystagmus vary in different positions of gaze. In many cases, a "neutral zone" exists in which the nystagmus is less pronounced or may even be absent. If the "neutral zone" is in the primary position of gaze, then the head position may be normal. If the neutral zone is in another position of gaze, then the patient may assume compensatory head position (CHP) to achieve optimal visual acuity. Methods of surgical treatment in these case are presented. The indications are based on measurement of compensatory head position or on amplitude of convergence in nystagmus blockage syndrome. The elimination of CHP is possible by the Anderson procedure or, in more advanced cases, by the Kestenbaum procedure and/or the artificial divergence procedure of Cüppers. Sometimes Cüppers procedure alone or in combination with recession of the muscles is indicated. Our own material and results of surgical treatment are presented in the next paper.

Head↗
PubMed1993

Is there a cholinergic and an adrenergic phase of the oculocardiac reflex during strabismus surgery?

We investigated the counterregulatory effect of the oculocardiac reflex (OCR) in 25 infants and children during strabismus surgery under three experimental conditions. In group 1, a series of measurements were recorded when the OCR was elicited by traction. The beat-to-beat heart rate reduction ranged from -26 to -64 beats/min (median: -46 beats/min). Constant traction increased heart rate in all patients from +23 to +50 beats/min (median: +30.5; P < 0.001). After a sudden release of the stimulation, heart rate rose further from +6 to +40 beats/min (median: +15; P < 0.001). In group 2, atropine (0.01 mg/kg) was administered 3-4 min prior to the same manipulations as in group 1. Constant traction changed heart rate from -1 to +20 beats/min (median: +4.5; P < 0.01). In group 3, a retrobulbar blockade suppressed the OCR and the counterregulation completely. These findings indicate that there is an active counterregulatory process which maintains heart rate during traction at the extraocular muscles after the bradycardic reflex has been initiated. The bradycardia and the counterregulation may be referred to as cholinergic and adrenergic phrases of the OCR. Atropine eliminates the cholinergic phase. Our study indicates that there may be receptors and afferent fibres for both phases, which can be blocked by local anaesthetics.

Adolescent↗
PubMed1993

[Emesis and the oculocardiac reflex. Drug prophylaxis with droperidol and atropine in children undergoing strabismus surgery].

Although droperidol is often used to prevent emesis, vomiting is still common in children undergoing strabismus surgery. METHODS. One hundred children aged 3 to 12 years admitted for strabismus surgery were enrolled in a randomised, double-blind study to investigate the influence of the timing of the administration of droperidol (75 micrograms/kg i.v.) and the effect of atropine (10 micrograms/kg i.v.) on postoperative vomiting and the occurrence of the oculocardiac reflex (OCR). Each child was prospectively assigned to one of the following groups: Group A: atropine and droperidol before the beginning of surgery (n = 25); Group B: atropine before the beginning, droperidol after completion of surgery (n = 25); Group C: no atropine, droperidol before the beginning of surgery (n = 25); Group D: no atropine, droperidol after completion of surgery (n = 25). After oral premedication with 0.4 mg/kg midazolam, anaesthesia was induced via a face mask by inhalation of halothane, nitrous oxide, and oxygen and 1 mg/kg succinylcholine was given to facilitate tracheal intubation. Gastric contents were aspirated by a gastric tube at the end of the operation. Vomiting and retching were recorded for 24 h; recovery from anaesthesia was assessed by a modified Steward score. RESULTS. The four groups were comparable regarding age, sex, body weight, duration of anaesthesia, and number of repaired eye muscles. Patients receiving droperidol before and after the end of surgery had a similar incidence of vomiting (groups A and C 60% vs. groups B and D 50%). There was no significant difference in the number of patients vomiting between groups A and B (58%) and groups C and D (52%). The incidence of the OCR was lower in the patients premedicated with atropine (18% vs. 60%, P < 0.01). There was no statistical relationship between the occurrence of the OCR and post-operative emesis. Younger children (3 to 6 years) vomited more often than older ones (7 to 12 years). The incidence of the OCR was higher in patients with more than two eye muscles repaired than in others. Recovery scores were slightly lower in patients with droperidol after completion of surgery; postoperative recovery times did not differ significantly between the study groups. CONCLUSIONS. The timing of the administration of droperidol (75 micrograms/kg) had no influence on postoperative vomiting. The application of atropine (10 micrograms/kg) prior to surgery did not influence vomiting after strabismus surgery. Atropine (10 micrograms/kg) reduced the incidence of the OCR significantly. There was no statistical relationship between the occurrence of the OCR and postoperative vomiting.

Atropine↗
PubMed1993

[The 4-prism diopter base-in test in diagnosis of exophoria with asthenopia and compensation by accommodative convergence].

About 30% of our patients suffering from purely binocular asthenopia showed lower binocular than monocular visual acuity. Cover test examination revealed exophoria at near fixation, which could be regarded to be physiological. Furthermore, the Pola test as well as Graefe's prism diplopia test showed no pathological findings. When given 4 prism base-in, a better binocular acuity was achieved and exophoria at for distance fixation was revealed. Often the prisms base-in had to be increased slowly and an operative treatment was indicated in 80%. The test is described in detail and examples from typical case studies are demonstrated. The importance of the test for understanding asthenopia in cases with heterophoria is discussed.

Accommodation, Ocular↗
PubMed1992

[Droperidol versus metoclopramide. Prevention of emesis following strabismus surgery in children].

Vomiting after strabismus surgery is a major problem that remains as yet unsolved, especially in children. Droperidol and metoclopramide, both known as powerful antiemetic drugs, were compared in this study. METHODS. One hundred ASA class I and II children ranging from 3 to 10 years of age were studied in a double-blind, randomised fashion. They were assigned to three groups: group D (n = 33) received 0.075 mg/kg droperidol, group M (n = 33) 0.15 mg/kg metoclopramide, and group N (n = 34) 0.1 ml/kg NaCl i.v. upon arrival in the post-anaesthesia recovery room (PARR). After oral premedication with 0.4 mg/kg midazolam, anaesthesia was induced via a face mask by inhalation of halothane, nitrous oxide, and oxygen. Barbiturates, atropine, and succinylcholine were not used; 0.05 mg/kg vecuronium was given to facilitate intubation. Gastric contents were aspirated by a gastric tube at the end of the operation. Vomiting and retching were recorded for 24 h; recovery from anaesthesia was assessed by a modified Steward score. RESULTS. The three groups were comparable regarding age, body weight, duration of anaesthesia, number of repaired eye muscles, and occurrence of the oculocardiac reflex (OCR). During the first 24 h postoperatively 21/33 (64%) patients of group D vomited, 24/33 (73%) of group M, and 33/34 (97%) of group N. The differences between groups D and N and between M and N were significant (P less than 0.01); comparison of groups D and M showed no statistical significance. Droperidol was more effective in reducing severe vomiting. Of the group N children, 47% vomited more than 6 times in 24 h compared to 18% of group M and 0% of group D. Age, sex, duration of anaesthesia, number of repaired eye muscles, and occurrence of the OCR had no influence on postoperative vomiting. Despite being administered at the end of the operation, droperidol did not prolong the patients' stay in the PARR. The post-anaesthetic scores for group D children were only slightly lower compared to groups M and N. CONCLUSIONS. Droperidol (0.075 mg/kg) and metoclopramide (0.15 mg/kg) both reduce postoperative vomiting after strabismus surgery. Droperidol seems to be more effective in reducing severe vomiting. Postoperative sedation after droperidol was not a major problem in our experience.

Child↗
PubMed1991

[Physiologic and pathologic rebound nystagmus. Description and comparison].

Using a binocular, infrared charged coupled device (CCD), an eye tracker coupled with an Olivetti M24 PC (resolution up to 0.1 degrees, scanning with 80 frames/s), the eye movements of 20 normal individuals with normal visual acuity and binocular function were recorded to detect physiological endpoint (EPN) and rebound nystagmus (RN). Each subject was asked to fixate a target located in the primary position (PP) and after 5 s of recording time, to look at a target either 50 degrees to the right or left of the PP for approximately 20 s and then return for the last few seconds to the PP, EPN recordings were made with the room lights on and RN recordings were made both with the lights on and in total darkness. A forehead and chin rest with bite board were used. Twelve of the 20 subjects showed EPN and RN with the lights on. The 8 subjects that did not demonstrate EPN also showed no RN with the lights on. Recordings from all 20 subjects showed RN in darkness. No differences in amplitude were found between the abducted and adducted eyes. Although clear differences in the characteristics of gaze paretic or drug-related lateral gaze nystagmus and EPN have been found, no systematic differences in RN under lighted conditions had been observed between patients and normal subjects.

Adult↗
PubMed1991

[Subclinical eye movements as an indicator for inheritance of congenital nystagmus and central nervous system disease].

Clinically unaffected relatives of families with a history of either inherited congenital nystagmus or inherited neurogenic muscular and cerebellar atrophy underwent electrooculographic examination under three distinct test conditions. We found an increase in the number of square wave jerks, a higher than normal intensity score (defined in terms of frequency X amplitude of an involuntary saccade, unit: o/s) and nystagmus as compared with 110 normal individuals ranging in age from 21 to 89 years. These findings suggest a possible autosomal dominant mode of inheritance in the case study of congenital nystagmus presented. The results show abnormal eye movements in some family members from a family with inherited cerebellar degeneration with acquired nystagmus, suggesting that these family members are affected with the disorder. This study documents the rarely described observation of a connection between inherited cerebellar degeneration with inherited distal neurogenic muscular atrophy.

Adult↗
PubMed1990

[Frontobasal osteoplastic orbitotomy in surgical treatment of intraorbital processes].

A modified frontobasal osteoplastic orbitotomy with reconstruction of the orbital roof for operative approach to intraorbital processes of any localization and of different origin (tumors, foreign bodies etc.) will be presented. After a small trapezium-shaped frontal craniotomy, the superior orbital rim and the orbital roof are resected in one piece by means of an oscillating saw. This "orbital flap" has a triangular shape, its long tip pointing to the canal of the optic nerve. There is no significant retraction of the frontal lobe by using microscope. The orbital flap is replaced and fixed by two miniplates of Luhr. This technique facilitates a significantly better exposure of all intraorbital structures than other surgical approaches, reduces operative trauma, and has better postoperative functional results. In the last 4 years we have operated upon 16 cases by means of this method, which will be presented. Although in many cases the frontal sinus was involved there was only one infection. Most common postoperative complication (50%) has been lesion of the levator palpebrae muscle followed by ptosis, which usually improved after 4-6 weeks.

Adolescent↗
PubMed1990

Morphometric comparison between human and rat abducens and oculomotor nerves.

A morphologic and morphometric comparison between normal human and rat extraocular muscle nerves was performed using a computer-assisted method to obtain scatter diagrams of relative sheath thickness (g ratio = quotient axon diameter/fiber diameter). Human and rat extraocular muscle nerves (nervus abducens and ramus medialis n. oculomotorii) were excised immediately before the nerve branching at the entering point into the muscle. There was no difference in the absolute number of myelinated fibers between the oculomotor and abducens nerves in both species. The distribution of myelinated fibers was classified according to their g ratios into a two-stage density cluster analysis. Two main populations of nerve fibers for human oculomotor and rat oculomotor and abducens nerves and three main populations for human abducens nerve were differentiated morphometrically and mathematically, differing in their relative sheath thicknesses. There are distinct differences between scatter diagrams of human and rat extraocular muscle nerves, in correlation with the basically different oculomotor functions of these two species. The morphometric differences between human and rat extraocular muscle nerves suggest a difference in the myelination process and the presence of functionally different nerve fibers, strongly indicated by the populations and subpopulations of myelinating nerve fibers peculiar to extraocular muscle. The existence of more than two different types of myelinated fibers in the human nerves implies that the traditional classification based on fiber caliber must be reviewed and a comparison of different classes of nerve and muscle fibers should be performed.

Abducens Nerve↗
PubMed1990

A reexamination of end-point and rebound nystagmus in normals.

In order to detail the characteristics of end-point (EPN) and rebound nystagmus (RN), two series of experiments were performed with infrared oculography for measurement of horizontal eye movements. Experiment 1 consisted of EPN recordings during sustained lateral gaze (40 degrees and 50 degrees) in 20 normal subjects. Experiment 2 consisted of recordings of RN in 5 normal subjects. Nine of 20 subjects demonstrated a jerk EPN. EPN almost always appeared immediately and was sustained for 15-25 sec. In Experiment 2, RN occurred in 5 of the 5 subjects who demonstrated EPN. The mean amplitude of RN was always less than that of EPN, and decayed over a 5-10-sec time period. The experiment demonstrated that RN can be evoked in normals even when a fixation target, in a fully lit room, is present.

Adult↗
PubMed1990

[Artificial divergence surgery in congenital nystagmus].

The treatment possibilities for nystagmus have been expanded by the addition of the artificial divergence procedure. This paper presents a study on 26 nystagmus patients with and without anomalous head posture and good binocular function and with detailed pre- and postoperative electronystagmographic records. All patients had been treated by artificial divergence by means of a prism base out before the operation. Seventeen patients showed significant improvement after the artificial divergence procedure. In 3 patients this procedure had to be combined with the classic Kestenbaum procedure. In 6 patients, the effect of artificial divergence with prisms was not satisfactory; thus, the Kestenbaum procedure was necessary. This study proves the effectiveness of the artificial divergence procedure alone or in combination with other procedures for treatment of anomalous head posture and the improvement of visual acuity and binocular vision.

Adolescent↗
PubMed1990

Normal square wave jerks in differing age groups.

This report details the characteristics of normal square wave jerks (SWJ) over a broad age range. Sixty normally sighted subjects, categorized into three age groups (35-49 yr, 50-64 yr, and 65-89 yr) underwent electrooculographic (EOG) examination to investigate the characteristics of normal SWJ. The frequency, duration, and amplitude of SWJ per minute were calculated in three clinically used test conditions: 1) with a fixation point in a lighted room; 2) with eyes closed and 3) in darkness without a fixation point. Results were compared over age and conditions as well as with the scores of 50 normal young subjects (20-37 yr). SWJ were recorded in all conditions, with the highest number found with closed eyes and in darkness for all age groups. Contrary to earlier findings, no statistical differences in frequency of SWJ per minute due to age were observed. These findings describe a range of normalcy for these three EOG conditions from which pathology can be inferred.

Adult↗
PubMed1989

Distribution of axial combinations in astigmatism patients.

A total of 527 astigmatic patients were examined for their axial distribution. The values taken for all eyes together confirmed the preponderance of "+" cylinder at an axis of 90 degrees. However, only a small percentage of patients demonstrated a 90 degree axis for each eye separately. Mirroring and parallel axes were more common and an asymmetric axial distribution was found most frequently. The influence of lid pressure on the development of astigmatism thus seems, according to our findings, unlikely. Genetic factors are more probable.

Astigmatism↗
PubMed1989

[Optic nerve damage following craniocerebral trauma. A critical analysis of trans-ethmoid decompression of the optic nerve].

Over a period of 10 years 39 patients who suffered an optic nerve compression after a craniocerebral trauma underwent transethmoidal decompression surgery. The operation was performed bilaterally on 5 patients. Fifty per cent of the patients involved suffered a blunt head or brain injury, the others a brain concussion or space-occupying haemorrhage. At the side of optic nerve compression we found specific signs and symptoms, such as negative or sluggish direct light reaction of the pupil, a wound on the lateral side of the eyebrow, bleeding from the nose, eyelid haematoma, maximum of skull fractures and intracranial haematomas. Since the coincidence of radiological and intraoperative findings was only 67%, the ophthalmological findings such as lack of direct pupil reaction with preserved consensual light reaction or progressive loss of vision after a corresponding traumatic incident are our guideline for performing transethmoidal decompression of the optic nerve. In comparison with the results of conservative therapy as published in the literature, we achieved restitution of the visual function in about 10% more of the cases.

Adolescent↗
PubMed1989

How normal are "normal" square wave jerks?

Fifty normally sighted young subjects underwent horizontal electro-oculographic (EOG) examination to investigate fixation stability of the saccadic system. The number of square wave jerks (SWJ) and saccades per minute were calculated in three clinically used test conditions: (1) with a fixation point; (2) in darkness; and (3) with eyes closed. SWJ were recorded in all conditions. The highest number of SWJ per minute were found in darkness and with closed eyes. The analysis of the findings shows a range of normalcy for these three clinically used EOG conditions from which pathology can be inferred.

Adult↗
PubMed1988

Fast-phase instabilities in normally sighted relatives of congenital nystagmus patients--autosomal dominant and x-chromosome recessive modes of inheritance.

Verification of inheritance in congenital nystagmus (CN) is only possible through the identification of more than one affected member in a family since in a single case there are no accurate clinical differentiations between "spontaneous" and inherited CN. We performed electronystagmographic examinations (ENG) to search for abnormal involuntary eye movements as a sign of heredity in seemingly unaffected members of CN families. ENG registrations were performed under three test conditions: (1) with the subject fixating a target, (2) with the room lights off and (3) with closed eyes. Fifty normally sighted individuals (group (a] underwent the test procedure to provide a baseline of normality. Five CN families (three dominant, two sex-linked recessive) were tested as group (b). The eye movement recordings were analysed in terms of nystagmus intensity (amplitude x frequency of the involuntary saccade). In every one of the five families, abnormalities in seemingly non-affected members could be demonstrated: in four families, fast-phase instabilities, in the fifth family a true (CN) (slow-phase instability). All certain gene carriers were diagnosed correctly by the ENG. These findings indicate a method for detecting slightly affected members in dominant pedigrees and female gene carriers in sex-linked mode of transmission.

Adult↗