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Biomedical subjects

H Mühlendyck

Publications and source records attributed to H Mühlendyck.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1988

Transethmoidal decompression of the optic nerve in the case of craniocerebral trauma.

Over a period of ten years, 39 patients who had suffered optic nerve compression after a craniocerebral trauma underwent transethmoidal decompression surgery. The operation was performed bilaterally on 5 patients. Fifty percent of patients involved suffered a blunt head or brain injury, the others brain compression or contusion. On the side of optic nerve compression, we found specific signs and symptoms of the compression such as negative or sluggish direct light reaction of the pupil, wounds on the lateral side of the eyebrow, bleeding from the nose, eyelid hematoma, skull fractures and intracranial hematomas. Since radiological and intraoperative findings were the same in only 67% of cases ophthalmological findings such as lack of direct pupil reaction occurring together with preserved consensual light reaction and progressive loss of vision after a traumatic incident are used as guideline for performing transethmoidal decompression of the optic nerve. Surgery produced restitution of visual function in about 10% more cases than conservative therapy reported in the literature.

Adolescent↗