Otmar Meienberg

Transcranial stimulation of the human frontal eye field by magnetic pulses

SummarySingle transcranial magnetic pulsed stimuli were applied over the cortical area of the putative right frontal eye field (FEF) in 11 healthy subjects. An especially designed figure of eight shaped twin coil was used, to focus the stimulus, the strength of which was adjusted to the individual motor threshold of the left hand muscles. Eye positions and movements were recorded by an infrared reflection technique. Three different experiments were performed: 1. Stimulation during different primary gaze position did not evoke any discernible eye movement. 2. Stimulation just prior to visually elicited horizontal saccades did not cause a significant alteration of the latency, velocity, or amplitude of the saccades. 3. Only stimulation during an antisaccade task induced a significant latency prolongation, when the stimulus was applied between 50 to 90 ms after the target flashed up. This latency prolongation was found in all subjects for the antisaccades to the right, with a statistically significant average latency difference of +66 ±55.5 ms. In contrast, the antisaccades to the left were prolonged in the female subjects only by an average of + 98 ± 41.8 ms (p=0.0064), whereas in the male subjects they did not alter with stimulation (average difference: -3 ±41.9ms, p=0.753). Significant latency prolongations were only obtained when the magnetic FEF stimuli were applied within a vulnerable period, which varied from subject to subject.

Neurologic disorder of vitamin E deficiency in acquired intestinal malabsorption

Fifteen years after onset of a malabsorption syndrome a 49-year-old man had sensory and ocuolomotor disorder with marked vitamin E deficiency. After 6 months of treatment with high parenteral doses of vitamin E, the neurologic signs slowly receded, but the patient died of gastrointestinal hemorrhage. Autopsy and sural nerve biopsy showed the changes in both central and peripheral nerves; these changes are considered characteristic of vitamin E deficiency.

Visual evoked potentials in acute occipital blindness

SummaryPattern-evoked and flash-evoked responses were recorded from four patients with acute blindness due to occipital ischaemia. No responses could be obtained with pattern stimulation. Flash stimulation, however, yielded well-reproducible potentials in all four cases in spite of practically complete visual loss. In one patient vision recovered completely while the three others showed poor or minimal recovery in restricted visual field areas only. It is concluded that the flash method is not appropriate for differentiation of occipital blindness from psychogenic visual disorders. Furthermore, preserved flashevoked potentials in the acute stage of occipital blindness cannot be taken as a reliable prognostic sign for visual recovery, as has been postulated by others. A possible extrastriate origin of these flash responses is discussed in view of recent theories on a second visual system.ZusammenfassungVon vier Patienten mit akuter Erblindung infolge bilateraler occipitaler Ischämie wurden visuell evozierte Potentiale mit Schachbrettmuster-und Blitz-Stimulation abgeleitet. Während sich bei der Musterstimulation keine verwertbaren Potentiale ableiten ließen, ergab der Blitzreiz in allen vier Fällen eindeutig reproduzierte Antworten trotz praktisch vollständiger Blindheit. Bei einer Patientin bildete sich der Sehverlust vollständig zurück, die drei anderen zeigten nur geringe oder minimale Erholung in umschriebenen Gesichtsfeldbezirken. Aufgrund dieser Beobachtung scheint die Blitzmethode zur Abgrenzung kortikaler Blindheit von Psychogenen Sehstörungen ungeeignet. Zudem sprechen die Befunde gegen die von einzelnen Autoren vertretene Ansicht, daß erhaltene blitzevozierte Potentiale bei akut kortikal Erblindeten eine gute Prognose für die Erholung des Sehens erwarten lasse. Die Frage des Entstehungsortes von Blitz-VEP bei kortikaler Blindheit wird im Lichte neuerer Erkenntnisse über das visuelle System erörtert und eine mögliche extrastriäre Entstehung diskutiert.

DETERIORATION OR ONSET OF MIGRAINE UNDER OESTROGEN REPLACEMENT THERAPY IN THE MENOPAUSE

Sirs: Oestrogen replacement therapy is being increasingly used in the menopause to t reat or prevent osteoporosis, to alleviate menopausal symptoms such as hot flushes, genitourinary symptoms, depression, and also with the intent of reduce the risk of cardiovascular disease [7, 8]. Because of so many proven or at least probable beneficial effects of such t reatment , possible sideeffects or even contraindications may be overlooked. Within 3 years we have seen ten menopausal women (i.e., about 3% of the 290 migraine patients seen during this time) using oestradiol cutaneous patches with a de-

Ischaemic oculomotor nerve palsy

SummaryOf 61 patients with isolated third nerve palsy, 23 (38%) had the characteristic clinical features of an ischaemic oculomotor nerve palsy. The essential sign of this usually painful disorder of acute onset was a marked discrepancy between complete or severe paresis of the extraocular muscles innervated by the third nerve, and sparing of the pupillary sphincter. All patients had completely recovered within 3 months. Fourteen had a history or on follow-up had other cranial mononeuropathies. Except for two patients, all were above the age of 60 years. Of the 23 cases, 11 had diabetes mellitus and 8 an abnormal glucose tolerance test, while in 4 the latter was normal. Almost all had hypertension and were overweight, and half were smokers. In 18 patients, four or five vascular risk factors were present.

Recording of Horizontal Saccadic Eye Movements: Methodological Comparison Between Electro-Oculography and Infrared Reflection Oculography

Simultaneous recordings with monocular direct current electro-oculography (EOG) and infrared reflection oculography (IROG) from the same eye were performed to investigate methodological differences. In six healthy volunteers 20 and 30 degree midline crossing horizontal saccades were recorded using different low bandpass filtering and two different temporal EOG electrode placements. Important dissimilarities with regard to peak velocity and saccade duration were found between the two recording techniques. The most striking difference was encountered in the abducting (temporal) saccades, where EOG measured significantly slower velocities and, in most instances, longer durations of the saccades. As a consequence, EOG usually measured faster adducting and IROG faster abducting saccades. This discrepancy was further demonstrated in two additional control groups of healthy individuals with the two methods used separately. The authors conclude that the IROG more faithfully reflects rapid eye movements within the...

Subclinical visual field defects in multiple sclerosis

SummaryFourteen patients with definite but inactive multiple sclerosis (MS) and 17 normal controls were examined with the automated perimeter octopus. Most of the patients had subclinical visual field defects, typically consisting of patchy, shallow scotomata located mostly in an area of between 15° and 30° eccentricity. In 8 patients, more than 15% of the tested visual field of at least one eye was abnormal. The severity and extent of the defects was unrelated to a history of optic neuritis. When visually evoked potentials (VEPs) of these subjects were examined using a reversing pattern, no correlation was found in the MS patients between prolonged VEP latencies and the location, depth or extent of visual field defects. Since subclinical visual field defects may be found in MS patients with normal VEP latencies, automated perimetry can be helpful in diagnosing some cases.

Carotidynia: report of eight cases and prospective evaluation of therapy

SummaryThe essential clinical features of eight cases of carotidynia are out-lined. As little is known about treatment, the effectiveness was evaluated of drugs used in some specific forms of vascular headache with similar pain characteristics. Indomethacin or flurbiprofen were shown to be potent drugs in the treatment of carotidynia.ZusammenfassungAnhand von acht Fällen von Karotidynie werden die wesentlichen klinischen Kriterien dieses Schmerzsyndroms hervorgehoben. Aus der bisherigen Literatur ist relativ wenig bekannt über Möglichkeiten der Behandlung. Es wurde daher die Wirksamkeit von Medikamenten, welche bei einigen Sonderformen von vaskulärem Kopfschmerz mit einem der Karotidynie ähnlichen Schmerzcharakter erfolgreich angewandt wurden, geprüft. Es stellte sich heraus, daß Indomethacin und Flurbiprophen in der Behandlung der Karotidynie eine gute Wirkung haben.

Primary position vertical nystagmus: ‘Directional preponderance’ of the pursuit system?

The essential disturbance in five patients with vertical nystagmus was an inability to generate smooth pursuit eye movements in the direction of the quick phase of their nystagmus. As the cause of this behavior, the authors suggest an asymmetric impairment of the visual input to the pursuit system. This defect causes a ‘directional preponderance’ of the pursuit system detectable as a continuous drift off target. The drift is interrupted by refoveating saccades, thus resulting in a vertical nystagmus. Fünf Patienten mit Vertikalnystagmus zeigten als wesentliche Störung eine Unfähigkeit, gleitende Folgebewegungen in Richtung der raschen Nystagmusphase auszuführen. Als Ursache dieser Störung nehmen Verff. eine asymmetrische Unterbrechung visueller Zuflüsse zum Folgesystem an. Durch diese Unterbrechung wird das normalerweise bestehende Gleichgewicht im Folgesystem gestört. Es entsteht ein ‚Richtungsüberwiegen‘ im Folgesystem, das sich in einem Abtreiben der Gesichtslinie vom ruhenden Fixierpunkt auswirkt. Dieses Abtreiben wird immer wieder durch Sakkaden korrigiert, so daß ein Nystagmus entsteht.

Normative data of saccadic eye movements for routine diagnosis of ophthalmoneurological disorders

With regard to the use of saccadic eye movements in the diagnosis of ophthalmo-neurological disorders, normative data were obtained from 40 eyes of 20 healthy subjects with an improved version of Infrared Reflection Oculography (IROG). Only such saccade parameters and tests were chosen which are suitable for routine examinations and the diagnostic value of which had already been demonstrated. Thus, accuracy, peak velocity, and duration of symmetrically midline-crossing 30- and 20-degree saccades were evaluated. Because age had a highly significant influence on several saccade parameters, age-specific normal ranges were calculated. Since highly significant differences for accuracy and peak velocity between abducting and adducting saccades were found, separate normative data for abduction and adduction were determined. In order to increase the yield of pathology in some ophthalmo-neurological disorders, standardized fatigue and Tensilon tests are proposed and their normal ranges given.