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Biomedical subjects

G Kommerell

Publications and source records attributed to G Kommerell.

At least 19 recordsLinked to original sources
PubMed1992

Misdirected regeneration of abducens nerve neurons into the parasympathetic pupillary pathway.

A 16-year-old girl suffered a severe head trauma with paralyses of the right oculomotor, trochlear, and abducens nerves. Three years later, only the abducens nerve had recovered. The pupil did not react to light or near. However, the diameter of the pupil correlated with horizontal gaze: with the gaze to the left, the diameter of the pupil was 8 mm, with the gaze straight ahead, 6 mm, and with the gaze to the right, 4 mm. With saccades to the right, the pupil started to constrict immediately and reached its smallest diameter after about 2 s. We conclude that the constriction of the pupil was due to misdirected regeneration of abducens nerve neurons into the parasympathetic pathway of the oculomotor nerve.

Abducens Nerve↗
PubMed1992

Albino-type misrouting of the optic nerve fibers not found in dissociated vertical deviation.

It has been suggested that albinolike misrouting of the visual pathway occurs in patients with dissociated vertical deviation (DVD). We re-examined this contention in ten DVD patients using visually evoked potentials. Full-field monocular pattern-onset checkerboard stimulation was employed. The visually evoked potentials were recorded simultaneously from both occipital lobes. Their differential activity during stimulation of the right eye was compared with that obtained during stimulation of the left. We found no predominance of crossed projection in any of the DVD cases. The results in nine normal subjects were similar. In 13 albino patients, however, there was a relative positivity in the contralateral hemisphere about 100 ms after pattern-onset, which reconfirmed predominance of the crossed projection. Possible artifacts are discussed that may have led to the assumption of misrouting in DVD in two previous reports.

Adolescent↗
PubMed1992

[Congenital nystagmus and intermittent exotropia. Suppression of nystagmus by fusional convergence].

We report on a patient with a combination of congenital nystagmus and intermittent exotropia. When the exotropia became manifest, a gross nystagmus appeared. When, however, the exotropia was overcome by fusinal convergence, the nystagmus was largely suppressed. The angle of squint was surgically reduced by such an amount that the exodeviation was just compensated, and the fusional convergence required to overcome the remaining angle sufficed to suppress the nystagmus.

Convergence, Ocular↗
PubMed1992

[Short-term effect of megadose steroid therapy in optic neuritis].

15 patients with unilateral optic neuritis and 2 patients with bilateral optic neuritis were treated with 1000 mg methylprednisolone i.v. per day for 5 days. In the cases of unilateral optic neuritis, visual acuity was reduced to < or = 0.1, in those with bilateral optic neuritis to < or = 0.6 in the better eye. The treatment was started one to 70 days after the onset of the neuritis. We examined whether vision recovered rapidly during the treatment. As a rapid recovery we defined a fourfold improvement on a logarithmic scale during the 5 days of methylprednisolone medication. Such a rapid recovery was found in 11 of the 15 patients with unilateral and in 1 of the 2 patients with bilateral optic neuritis. A similar recovery was not found before and after the treatment interval. Although we did not have a control group, the correlation in time between the therapy and the rapid recovery suggests that the megadose steroids were effective in our patients. This interpretation is compatible with the results of the randomized controlled multicenter trial of Beck et al. (New Engl. J. Med. 326:81, 1992): However, the beneficial effect was seen up to 6 months only; one year after treatment, visual functions did no longer differ between the megadose and the placebo groups. Low-dose oral steroids did not improve visual function at any time and carried a higher risk for new episodes of neuritis, compared to placebo. Therefore, the "traditional" low-dose steroid therapy for optic neuritis has become obsolete.

Adolescent↗
PubMed1992

Leber's hereditary optic neuroretinopathy and the X-chromosomal susceptibility factor: no linkage to DXs7.

Leber's hereditary optic neuroretinopathy (LHON) was the first human disease for which mitochondrial inheritance was demonstrated. Analysis of genealogies, however, suggests the existence of an interacting X-linked factor, and linkage to DXS7 was recently described. We tested this location in four LHON families, with DXS7 and two flanking markers, OTC and DXS426. We found recombinations with DXS7 in two families and with DXS426 in one. The two point lod scores to DXS7 were negative with all the allele frequencies for the X-linked factor tested (q = 0.5; 0.35; 0.05).

Female↗
PubMed1991

[Vertical accommodative vergence].

Five patients showed vertical accommodative vergence during which the strabismic eye deviated either up- or downwards. Additional components of strabismus included intermittent or constant exotropia, dissociated vertical divergence, and various incomitancies. There were no signs of misdirected regeneration after oculomotor palsy. We interpret vertical accommodative vergence as a supranuclear abnormality, most likely congenital.

Adult↗
PubMed1990

[Differential diagnosis of optic nerve atrophy].

Diseases of the visual pathway: early detection and therapy. Manual kinetic perimetry is faster in the detection of lesions of the visual pathway than automated static perimetry. When cases with a comparable reduction of visual acuity are considered, color desaturation is more pronounced in lesions of the visual pathway than in opacities of the optic media. Search for an afferent pupil defect allows the differential diagnosis between functional and unilateral organic visual impairment: in the case of bilateral visual impairment, a combination of VEP and pattern ERG is suitable for this differentiation. In chronic papilledema, secondary atrophy can best be detected in the arcuate retinal nerve fibers. Fistulation of the dural sheath of the optic nerve prevents visual loss in chronic papilledema. A similar operation could be useful in the progressive form of anterior ischemic optic neuropathy. Recently, the mitochondrial DNA mutation associated with Leber's hereditary optic neuropathy was identified. Prolactin secreting pituitary adenomas shrink with bromocriptine treatment.

Color Perception↗
PubMed1990

[Amblyopia: reading speed in comparison with visual acuity for gratings, single Landolt Cs and series Landolt Cs].

In the treatment of amblyopia in preschool children, a means of predicting later reading ability would be helpful. This prediction might be possible using a test for visual acuity where the results correlate with reading ability in adult patients with amblyopia. We measured the following four parameters in 18 experienced readers with strabismic amblyopia: (1) time spent reading ten lines of a standard text in one of three magnifications, (2) visual acuity for gratings, (3) visual acuity for single Landolt Cs, and (4) visual acuity for crowded Landolt Cs (one Landolt C flanked by two full rings on each side each at a distance of 2.6 min of arc). The reading text was presented on paper at a distance of 40 cm; the subject had a choice of three magnifications. The acuity tests were generated by a computer on a VDU at 4.6 m. The relative impairment of the amblyopic eye was defined as the quotient between the performance of the amblyopic and the good eye. In addition, the difference between the times spent reading the ten lines with the amblyopic and with the good eye was calculated.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Increased muscle tension and reduced elasticity of affected muscles in recent-onset Graves' disease caused primarily by active muscle contraction.

In 3 patients with Graves' disease of recent onset, length-tension diagrams were made during surgery for squint under eyedrop anesthesia. The affected muscles were found to be very stiff when the other eye looked straight ahead. It was expected that these stiff muscles would be able to shorten to some extent but would be unable to lengthen, due to fibrosis of the muscle. We found that the affected muscles did not shorten very much when the other eye looked into the field of action of the muscle. Unexpectedly however, they lengthened considerably when the other eye looked out of the field of action of the muscle. This finding implies that the raised muscle tension and reduced elasticity of affected muscles in these cases of Graves' disease of recent onset were primarily caused by active muscle contraction, not by fibrosis.

Diplopia↗
PubMed1989

Preoperative prism adaptation test in normosensoric strabismus.

In 19 patients with normosensoric esotropia, the squint angles measured with the alternate cover test were compared with those after prolonged prismatic correction of the squint angle and with those after prolonged occlusion of one eye. All patients showed an increase of the squint angle after prism adaptation. The angle was generally smaller after diagnostic occlusion of one eye than after prism adaptation. We assume that the increase in the squint angle after prism adaptation is caused by an anomalous sensorial relationship between the two eyes that was not detected with the usual psychophysical tests. Surgery tailored to the squint angle after prism adaptation seems advisable in patients with normosensoric esotropia.

Adaptation, Ocular↗
PubMed1989

The effect of prolonged monocular occlusion on latent nystagmus in the treatment of amblyopia.

We recorded eye movements in 8 patients with latent nystagmus (LN) before and after 2 days of occlusion of the better eye. The slow-phase speed of the nystagmus (SPS) during fixation with the worse eye became lower after 2 days of occlusion of the better eye. However, the SPS during fixation with the better eye became higher after 2 days of occlusion of the better eye. The sum of SPS during fixation with the better eye and SPS during fixation with the worse eye remained the same. Oscillopsia complaints gradually disappeared over days during the occlusion. It seems likely that the alteration of the LN during prolonged monocular vision is caused by a slow-velocity bias of the neural integrator, a compensatory drift, generated by the flocculus using retinal-slip information. The difference between SPS during fixation with the better eye and SPS during fixation with the amblyopic eye in LN patients with amblyopia is probably also caused by this compensatory drift. As the compensatory drift changes its direction and magnitude slowly over days, it seems advisable to occlude the better eye in children with amblyopia and LN during days per week, and not during hours per day.

Adaptation, Ocular↗
PubMed1989

[Predominance of crossed optic nerve fibers is a characteristic of albinism, but not of dissociated vertical deviation].

We examined eight patients with dissociated vertical deviation (DVD) for evidence of misrouting in the visual pathway, using visually evoked potentials. Full-field monocular pattern-onset chequerboard stimulation was employed. The visually evoked potentials were recorded from both occipital lobes. Their differential activity during stimulation of the right eye was compared with that obtained during stimulation of the left eye. In contrast to an earlier report, a predominance of the crossed projection was not found in any of the DVD cases. The results in eight normal control subjects were similar, unlike our findings in eight albino patients (predominance of crossed projection: a relative positivity over the contralateral hemisphere about 100 ms after pattern-onset). Possible artifacts are discussed that may have led to the earlier assumption of misrouting in DVD patients.

Adolescent↗
PubMed1988

Extended pterional decompression of the orbit: an alternative treatment in endocrine orbitopathy.

Extended pterional decompression was performed in seven orbits. The indication was optic neuropathy in six orbits and corneal ulceration in one. As compared to ethmoidectomy, advantages of the pterional approach seem to be the preservation of the motility of the eye and the lack of paranasal sinus complications. We consider the pterional approach to be appropriate for decompression of endocrine orbitopathies that do not respond to conservative measures.

Corneal Diseases↗
PubMed1988

[Pseudo-spontaneous nystagmus with Frenzel eyeglasses].

The small light sources of Frenzel's glasses can induce Purkinje's figure on the retina. This is a stabilised retinal figure that may elicit an artificial "Leuchtbrillen-Nystagmus" which is easily mistaken for a spontaneous vestibular nystagmus. Provided with special instructions on how to induce Purkinje's figure, 22 of 55 normal subjects were able to produce nystagmus with Frenzel's glasses. This pseudo-spontaneous nystagmus should be avoided by using a pair of glasses, that cannot induce Purkinje's figure. Such glasses are currently being developed in our laboratory.

Adult↗
PubMed1986

Congenital nystagmus: control of slow tracking movements by target offset from the fovea.

Patients with congenital nystagmus (CN) are unable to respond adequately to optokinetic stimuli. This suggests that patients with CN do not use the movement of images (slip) across the retina as a control variable for their eye movements. Nevertheless, they are capable of tracking moving targets with slow eye movements. Experiments using paracentral afterimages as targets for fixation suggest that these slow tracking movements may be executed by the control of target position on the retina rather than slip across the retina: all seven patients with CN produced slow tracking movements, superimposed on nystagmic cycles. The fact that the basic parameters of the CN waveform remained unchanged under the open-loop condition constituted by afterimage tracking (only the amplitude was reduced in four out of seven patients) indicates that the timing and direction of slow and rapid components of CN do not depend on retinal feedback. During refixations between stationary targets, some patients with CN occasionally acquired the target with a slow, rather than a saccadic movement. This finding further supports the notion that patients with CN use target offset from the fovea as a very effective control variable not only for rapid, but also for slow eye movements.

Adult↗
PubMed1986

Visual localization after strabismus surgery is compatible with the "outflow" theory.

Strabismic patients pointed at visual targets, presented monocularly, without sight of the pointing arm. After surgical rotation of one eye in the orbit the pointing responses were shifted by a similar amount in the opposite direction in 13 out of 14 patients; this outcome corresponds to the predictions of the outflow theory of visual localization. Occasional differences between predicted and actual response shifts can be attributed to the well-known ambiguity of localization in strabismics.

Humans↗