Konrad P. Weber

University Hospital Zürich · Neurology and Ophthalmology

Zusammenfassung. Die idiopathische intrakranielle Hypertension ist eine sekundäre Kopfschmerzerkrankung und Optikusneuropathie bei erhöhtem intrakraniellem Druck. Sie betrifft vorwiegend adipöse Frauen im gebärfähigen Alter und stellt sowohl diagnostisch als auch therapeutisch eine interdisziplinäre Herausforderung dar. Häufigstes Symptom dieser Er...

The invention relates to a method for determining a position, particularly a coronal position of an eye relative to a coronal plane of the head of a person, with a handheld 3D-surface scanning device, the method comprising the steps of: Acquiring a digital data set comprising information about a three- dimensional surface and texture of at least a...

Background Disorders affecting the vestibular organs (semicircular canals, utriculus, sacculus), may result in distinct patterns of peripheral-vestibular loss that may facilitate the diagnostic assessment. When neuropathological tests of these sensors are available, it is possible to classify responses as being due to different deficit types. Objec...

Optikusneuritis, im Englischen optic neuritis, bezeichnet eine Entzündung des Nervus opticus und stellt somit eine Affektion des Zentralen Nervensystems (ZNS) dar. Weil die Symptomatik das visuelle System betrifft, wenden sich Betroffene primär an eine augenärztliche Einrichtung. Im Verlauf der Erkrankung ist eine enge interdisziplinäre Zusammenarb...

In clinical practice, the head impulse test paradigm (HIMP) and the suppression head impulse paradigm (SHIMP) stimulate high-frequency head movements so that the visual system is temporarily suppressed. The two tests could also be useful tools for vestibular assessment at low frequencies: VVOR (visually enhanced vestibulo-ocular reflex) and VORS (v...

Oculomotor palsy with cyclic spasms is an extremely rare condition whose exact pathophysiology remains a mystery. We followed a boy from the onset of symptoms at the age of ten months until 15 years and documented the case with video oculography. In addition, he was diagnosed with hereditary motor and sensory neuropathy (Charcot-Marie-Tooth disease...

Background: Visual snow is considered a disorder of central visual processing resulting in a perturbed perception of constant binocular flickering or pixilation of the whole visual field. The underlying neurophysiological and structural alterations remain elusive. Methods: In this study, we included patients (final n = 14, five dropouts; five femal...

Objectives Quantitative vestibular testing in athletes after sports-related concussion (SRC) has become more popular due to accompanying injuries of the peripheral-vestibular organs that require targeted treatment. Sports-specific normative values are currently not available. Taking into account potential adaptational mechanisms, we obtained sports...

Background: Brown syndrome is characterized by a restrictive elevation deficit of the affected eye in adduction. Besides the well-known congenital form, different acquired etiologies including inflammation, trauma, and surgery may prevent the superior oblique (SO) tendon from gliding freely through the trochlea on attempted upgaze. We present MRI...

The Hess and the Harms screen test each have different testing distances. While the Harms screen test is usually performed at 2.5 m, the Hess screen test is performed at 0.5 m. The geometry of the closer testing distance of the Hess screen test requires an increase of the convergence angle by 6°. This study investigates the quantitative differences...

Background: Patients with vestibular schwannoma that show residual peripheral-vestibular function before surgery may experience sudden and substantial vestibular loss of function after surgical resection. To alleviate the sudden loss of peripheral-vestibular function after vestibular-schwannoma (VS) resection, pre-surgical intratympanic gentamicin...

Background: Early brainstem neurodegeneration is common in Parkinson's disease (PD) and progressive supranuclear palsy (PSP). While previous work showed abnormalities in vestibular evoked myogenic potentials (VEMPs) in patients with either disorder as compared to healthy humans, it remains unclear whether ocular and cervical VEMPs differ between PD...

Objective: Visual snow (VS) is a distressing, life-impacting condition with persistent visual phenomena. VS patients show cerebral hypermetabolism within the visual cortex, resulting in altered neuronal excitability. We hypothesized to see disease-dependent alterations in functional connectivity and gray matter volume (GMV) in regions associated w...

Objective: To test the hypothesis that patterns of semicircular canal (SCC) and otolith impairment in unilateral vestibular-loss depend on the underlying disorders, we analyzed peripheral-vestibular function of all five vestibular sensors. Methods: Retrospective case-series. Screening of the hospital video-head-impulse test database (n=4983) for...

Timely and accurate diagnosis of myasthenia gravis, particularly in patients with fluctuating, isolated ocular involvement, remains challenging. Serological antibody testing and repetitive nerve stimulation of peripheral muscles usually have low sensitivity in these patients. Edrophonium testing may cause adverse events, single-fiber electromyograp...

Background Depressive symptoms in myasthenia gravis (MG) are common, may mimic other disease features, and contribute to misdiagnosis and diagnostic delay. Nevertheless, the clinical determinants of depressive symptoms in MG remain poorly studied, in particular their overlap with fatigue. Moreover, studies in MG have rarely looked at distinct depre...

Background: This study aimed to determine whether vestibular rehabilitation using active video games (Exergames), including promoted head turns and unsupported locomotion, may facilitate vestibular compensation and gait in subjects with one-sided chronic peripheral vestibular hypofunction (cPVH). Methods: 12 patients with cPVH (mean age of 65 ± 12...

Objective To validate the repetitive ocular vestibular evoked myogenic potentials (RoVEMP) test for diagnostic use in myasthenia gravis (MG) and to investigate its value in diagnostically challenging subgroups. Methods The RoVEMP test was performed in 92 patients with MG, 22 healthy controls, 33 patients with a neuromuscular disease other than MG...

Objective: While positional nystagmus of benign paroxysmal positional vertigo (BPPV) has been shown to be detectable in electrooculography (EOG) tracings of polysomnography (PSG), the frequency of undiagnosed BPPV in patients referred for sleep-wake examination has never been investigated. Methods: Prospective evaluation of positional nystagmus...

Background Disease burden in myasthenia gravis (MG) and in other autoimmune disorders is often determined by common accompanying symptoms such as fatigue, sleepiness and mood disturbances. Many MG patients have a second autoimmune disease, but it is unclear whether autoimmune comorbidities add to the severity of fatigue, sleepiness and mood disturb...

Objective: To determine the most effective stimulation parameters for the diagnosis of ocular myasthenia gravis (MG) using repetitive ocular vestibular evoked myogenic potentials (oVEMP) for quantification of the extraocular muscle response decrement. Methods: Repetitive bone-conducted oVEMPs were elicited in 18 MG patients and 20 healthy subjec...

The short-latency vestibulo-collic reflex in humans is well defined for only the sternocleidomastoid (SCM) neck muscle. However, other neck muscles also receive input from the balance organs and participate in neck stabilization. We therefore investigated the sound-evoked vestibular projection to the splenius capitis (SC) muscles by comparing surfa...

Introduction: Patients with suspected Horner's syndrome having equivocal pupil dilation lag and pharmacologic testing may undergo unnecessary MR imaging and work up in the case of false positive pupil test results. Our goal was to increase the diagnostic accuracy of pupillometry by accentuating the inter-ocular asymmetry of sympathetic innervation...

Pupillometry with electrical stimulation in a patient with left Horner's syndrome. A single electrical stimulation is delivered during constant low light-on (0.1 log-lux).

Pupillometry without electrical stimulation in a patient with left Horner's syndrome. 5 cycles of light and dark alone without electrical stimulation.

Pupillometry with electrical stimulation in a patient with left Horner's syndrome. A triple electrical stimulation is delivered during constant low light-on (0.1 log-lux).

Pupillometry with electrical stimulation in a patient with left Horner's syndrome. A single electrical stimulation is delivered during each cycle of light and dark, 2 seconds after the termination of light.

Pupillometry with electrical stimulation in a patient with left Horner's syndrome. A triple electrical stimulation is delivered during each cycle of light and dark, 2 seconds after the termination of light.

Background The subjective feeling of fatigue in myasthenia gravis (MG) is poorly elucidated, in part because it is often confounded with the objective sign of muscle fatigability. Another reason is the paucity of validated fatigue questionnaires in MG. Methods We applied the 9-item Fatigue Severity Scale (FSS) and the 40-item Fatigue Impact Scale (...

Background: Recurrent optic neuritis (rON) associated with myelin oligodendrocyte glycoprotein (MOG)-specific antibodies has been initially reported to show a better clinical outcome than aquaporin-4 (AQP4)-seropositive ON in neuromyelitis optica spectrum disorder (NMOSD). Here, we characterize clinical and neuroimaging findings in severe cases of...

Background Gait imbalance and oscillopsia are frequent complaints of bilateral vestibular loss (BLV). Video-head-impulse testing (vHIT) of all six semicircular canals (SCCs) has demonstrated varying involvement of the different canals. Sparing of anterior-canal function has been linked to aminoglycoside-related vestibulopathy and Menière’s disease....

This chapter deals with chemical and hematologic investigations which are often considered in the diagnostic workup of subacute to chronic cerebellar ataxias. Relevant investigations in blood (serum, plasma), urine, and cerebrospinal fluid are discussed. Particular attention is paid to early diagnosis of treatable metabolic ataxias (such as abetali...

This chapter deals with chemical and hematologic investigations which are often considered in the diagnostic workup of subacute to chronic cerebellar ataxias. Relevant investigations in blood (serum, plasma), urine, and cerebrospinal fluid are discussed. Particular attention is paid to early diagnosis of treatable metabolic ataxias (such as abetali...

Objective: We aimed to quantify peripheral-vestibular deficits that may contribute to imbalanced stance/gait in patients with inflammatory neuropathies. Methods: Twenty-one patients (58 ± 15 y [mean age ± 1SD]; chronic-inflammatory-demyelinating-polyneuropathy = 10, Guillain-Barré Syndrome = 5, Anti-MAG peripheral neuropathy = 2, multifocal-moto...

The varying combination of fluctuating ptosis, diplopia, and fatigability of orbicularis oculi and extraocular eye muscles, but with normally reacting pupils, is typical for ocular myasthenia gravis. Up to 80 % of patients will develop generalized myasthenia gravis within two years. Diagnosis is often delayed, because symptoms are often insidious a...

Purpose: To assess the validity of a novel, simplified, noninvasive test for strabismus using video goggles. Design: Cross-sectional method comparison study in which the new test, the strabismus video goggles, is compared with the existing reference standard, the Hess screen test. Participants: We studied 41 adult and child patients aged ≥6 ye...

In 1988, we introduced impulsive testing of semicircular canal (SCC) function measured with scleral search coils and showed that it could accurately and reliably detect impaired function even of a single lateral canal. Later we showed that it was also possible to test individual vertical canal function in peripheral and also in central vestibular d...

Objective Balance problems are a frequent symptom after head trauma including concussion, and the Balance Error Scoring System (BESS) is routinely used as a subjective screening test. Low-cost inertial sensors are an attractive objective alternative to elaborative force plates in objective testing balance in athletes. Design Case series. Setting...

Objectives The video-head-impulse test (vHIT) provides a functional assessment of all six semicircular canals (SCC). Occasionally isolated loss of the posterior canal(s) (ILPC) is diagnosed, though this finding is poorly characterized. Here we assessed how accurate that diagnosis is by measuring the co-occurrence of abnormalities on caloric irrigat...

A head mountable device for measuring eye movement includes: a frame; a camera system comprising a first camera, wherein the camera system is coupled to the frame, and is configured to obtain a first set of images of a first eye of a user; and a first liquid crystal display (LCD) shutter configured to control passage of light to the first eye based...

Objectives Amyotrophic lateral sclerosis (ALS) has been reported to occur with increased incidence amongst physically active people. The role of extrinsic risk factors as physical activity, head trauma and drug/pesticide‐exposure in the pathophysiology of ALS and especially in the context of practising sports remains controversial. Materials and M...

PURPOSE Enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD OCT) has been recognized as the most sensitive tool to diagnose optic nerve head drusen (ONHD). The relationship between OCT characteristics and visual loss has not been well documented. This study compares EDI SD OCT-determined morphologic characteristics of drus...

Objectives: During head rotations, neuronal firing rates increase in ipsilateral and decrease in contralateral vestibular afferents. At low accelerations, this "push-pull mechanism" is linear. At high accelerations, however, the change of firing rates is nonlinear in that the ipsilateral increase of firing rate is larger than the contralateral dec...

Background: Both the dynamic visual acuity (DVA) test and the video head-impulse test (vHIT) are fast and simple ways to assess peripheral vestibulopathy. After losing peripheral vestibular function, some patients show better DVA performance than others, suggesting good compensatory mechanisms. It seems possible that compensatory covert saccades c...

Purpose: Enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD OCT) has been recognized as the most sensitive tool to diagnose optic nerve head drusen (ONHD). The relationship between OCT characteristics and visual loss has not been well documented. This study compares EDI SD OCT-determined morphologic characteristics of dr...

Objective: Rotational vestibular function declines with age resulting in saccades as a compensatory mechanism to improve impaired gaze stability. Small reductions in rotational vestibulo-ocular reflex (VOR) gain that would be considered clinically normal have been associated with compensatory saccades. We evaluated whether compensatory saccade char...

Objective: While compensatory saccades indicate vestibular loss in the conventional head impulse test paradigm (HIMP), in which the participant fixates an earth-fixed target, we investigated a complementary suppression head impulse paradigm (SHIMP), in which the participant is fixating a head-fixed target to elicit anticompensatory saccades as a s...

Objective: Bilateral vestibular loss (BVL) is often diagnosed with great delay and an underlying cause is only identified in 50-80%. We measured horizontal and vertical semicircular canal function using the video-head-impulse test (vHIT) and hypothesized that specific vHIT-patterns may be linked to certain etiologies. Methods: We retrospectively...

Hepatitis C is frequently accompanied by immune-related extrahepatic manifestations affecting the skin, kidneys, central and peripheral nervous system and exocrine glands. We present the case of a 40-year-old man with left-sided ptosis, exophthalmos and headache. MRI demonstrated left-sided orbital pseudotumor with lacrimal and retro-orbital contra...

Largely based on findings from functional neuroimaging studies, the medial parietal lobe is known to contribute to internally directed cognitive processes such as visual imagery or episodic memory. Here, we present 2 patients with behavioral impairments that extend this view. Both had chronic unilateral lesions of nearly the entire medial parietal...