[Video-based head impulse test. Importance for routine diagnostics of patients with vertigo]. / Videobasierter Kopfimpulstest. Bedeutung für die Routinediagnostik von Schwindelerkrankungen.

Dizziness is one of the most common complaints in Germany which leads to medical consultation. Diagnosis is based on patient history, clinical examination and laboratory tests. In order to find or exclude a vestibular lesion, methods such as caloric irrigation, rotational chair tests or vestibular-evoked myogenic potentials were previously applied. Recently, a new diagnostic tool has been made available for application in daily practice: the video head impulse test (vHIT). Due to the easy and fast application for the examiner, good tolerance by the patient and high sensitivity for vestibular lesions, the vHIT has the potential to improve the diagnosis and therapy of patients suffering from vertigo in widespread medical care in Germany. This article reports on experiences with this new method after examination of over 1,500 patients in the academic vertigo centre in Lübeck. The principles and application of the vHIT in daily clinical routine are described and the many advantages but also some pitfalls are highlighted. As a consequence of a wider clinical use it is expected that the vHIT will lead to an increased detection of vestibular dysfunctions not only in clinically suspected vestibular diseases but also in other common neurological diseases (e.g. polyneuropathy or cerebellar ataxia). This may change the prevalence of different vestibular diseases, broaden knowledge about other common diseases with gait imbalance as the leading symptom and provide a quantitative measure that can be used to longitudinally assess the effects of therapeutic interventions.

Vergence deficits in patients with cerebellar lesions.

The cerebellum is part of the cortico-ponto-cerebellar circuit for conjugate eye movements. Recent animal data suggest an additional role of the cerebellum for the control of binocular alignment and disconjugate, i.e. vergence eye movements. The latter is separated into two different components: fast vergence (to step targets) and slow vergence (to ramp and sinusoidal targets). The aim of this study was to investigate whether circumscribed cerebellar lesions affect these dynamic vergence eye movements. Disconjugate fast and slow vergence, conjugate smooth pursuit and saccades were binocularly recorded by a scleral search coil system in 20 patients with acute cerebellar lesions (all ischemic strokes except for one) and 20 age-matched healthy controls. Patients showed impairment of slow vergence while fast vergence was unaffected. Slow vergence gain to sinusoidal targets was significantly reduced, both in convergence and divergence direction. Divergence but not convergence velocity to ramp targets was reduced. Conjugate smooth pursuit eye movements to sinusoidal and to step-ramp targets were impaired. Patients had saccadic hypometria. All defects were particularly expressed in patients with vermis lesions. In contrast to recent animal data fast vergence was not impaired in any of our patient subgroups. We conclude that (i) the human cerebellum, in particular the vermis, is involved in the processing of dynamic vergence eye movements and (ii) cerebellar lesions elicit dissociable effects on fast and slow vergence.

Eye movement disorders are different in Parkin-linked and idiopathic early-onset PD.

OBJECTIVES: Parkin gene mutations are the most common cause of early-onset parkinsonism. Patients with Parkin mutations may be clinically indistinguishable from patients with idiopathic early-onset Parkinson disease (EOPD) without Parkin mutations. Eye movement disorders have been shown to differentiate parkinsonian syndromes, but have never been systematically studied in Parkin mutation carriers. METHODS: Eye movements were recorded in symptomatic (n = 9) and asymptomatic Parkin mutation carriers (n = 13), patients with idiopathic EOPD (n = 14), and age-matched control subjects (n = 27) during established oculomotor tasks. RESULTS: Both patients with EOPD and symptomatic Parkin mutation carriers showed hypometric prosaccades toward visual stimuli, as well as deficits in suppressing reflexive saccades toward unintended targets (antisaccade task). When directing gaze toward memorized target positions, patients with EOPD exhibited hypometric saccades, whereas symptomatic Parkin mutation carriers showed normal saccades. In contrast to patients with EOPD, the symptomatic Parkin mutation carriers showed impaired tracking of a moving target (reduced smooth pursuit gain). The asymptomatic Parkin mutation carriers did not differ from healthy control subjects in any of the tasks. CONCLUSIONS: Although clinically similarly affected, symptomatic Parkin mutation carriers and patients with idiopathic EOPD differed in several oculomotor tasks. This finding may point to distinct anatomic structures underlying either condition: dysfunctions of cortical areas involved in smooth pursuit (V5, frontal eye field) in Parkin-linked parkinsonism vs greater impairment of basal ganglia circuits in idiopathic Parkinson disease.

Central representation of cold-evoked pain relief in capsaicin induced pain: an event-related fMRI study.

The termination of an unpleasant or painful somatic condition can produce a rewarding sense of relief, even if the stimulus that causes the termination is itself unpleasant or painful under normal circumstances. We aimed to identify central neural mechanisms of pain relief from capsaicin-elicited heat-hyperalgesia by administering cold stimuli. We hypothesized that cooling might facilitate endogenous descending inhibitory mechanisms. We compared intraindividual neural responses of 15 healthy male volunteers to cold (20, 0 degrees C), intermediate (30 degrees C) and heat stimuli (43 degrees C) on untreated vs. capsaicin-treated skin using event-related fMRI in a 2 x 4 factorial design. Thermal stimuli were applied at the right hand in two separate imaging sessions using a Peltier-element. Psychophysical ratings of the perceived valence and intensity (VAS: 1-100) were obtained after each stimulus. The 43 degrees C-stimulus was perceived as excessively painful on capsaicin-treated skin as opposed to an unpleasant sensation on normal skin. In contrast, the 0 degrees C-stimulus was perceived unpleasant when applied on untreated skin while subjects rated the same stimulus pleasant in the capsaicin-treated condition. When neural responses to the 0 degrees C-stimulus were compared between the untreated and capsaicin-treated skin condition there were stronger BOLD-responses in prefrontal cortex (PFC) and periaqueductal grey (PAG) which correlated with increasing perceived pleasantness (VAS). Based on a connectivity analysis which identified cold-dependent contributions of PFC activity with PAG in heat-hyperalgesia we propose that cold-induced pain relief partly results from activation of endogenous descending inhibition of nociception. The data illustrate that perception of nociceptive input may largely be determined by competing aversive-appetitive motivational states.

[Simultaneous presentation of amyotrophic lateral sclerosis and multiple sclerosis]. / Kombiniertes Auftreten von amyotropher Lateralsklerose und Multipler Sklerose.

The concurrence of amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS) is extremely rare. We report on a 55-year-old female patient presenting with a progressive gait disorder for 6 months and a speech disorder for 3 months. Neurological examination revealed a spastic paraparesis and mild dysarthria and dysphagia. Technical and laboratory investigations met the diagnostic criteria for MS: magnetic resonance imaging showed multiple periventricular white matter and cervical lesions; cerebrospinal fluid showed a typical autoimmune response. Within the following 3 months generalized fasciculations, atrophy of the small hand muscles and bulbar signs were noticed. Nerve conduction studies revealed acute and chronic signs of denervation in all limbs without nerve conduction block. Hence clinical and paraclinical examination met the El Escorial criteria for ALS. Although myelitic lesions in the anterior horn cells may lead to peripheral segmental denervation, the generalized denervation suggested the unusual coincident combination of ALS and MS in this patient. In clinical praxis motoneuron diseases should also be considered in patients with pronounced peripheral denervations once "definite" MS has been diagnosed.