Case report: A disconjugate pattern in video head impulse testing hints toward a central cause of acute vertigo.

When acute vertigo occurs, the challenge for the medical practitioner lies in the focused assessment to find the cause of its symptoms. Especially in the case of central pathology, a fast diagnosis is essential for therapy. The head impulse, nystagmus, test of skew (HINTS) protocol and the additional video head impulse test (VHIT) can distinguish between central and peripheral vestibular causes in the acute setting and thus help to set the right path for further evaluation and treatment. In this case, a patient with acute onset of vertigo presented with an unusual pattern in the VHIT. Binocular eye tracking showed a disconjugate horizontal vestibulo-ocular reflex (VOR) with severe loss or gain for the adducting eye yet with a lack of corrective saccades. The abducting eye produced a pattern of mild VOR gain loss yet with pronounced corrective saccades. Together with clinical findings that were compatible with internuclear ophthalmoplegia, a probable central lesion in the medial longitudinal fasciculus (MLF) region was suspected. The patient was sent to a tertiary hospital, where the initial MRI was negative, but due to additional neurological symptoms occurring later, multiple lesions in the cervical spine and cerebellum were detected. The hypothesis of an inflammatory demyelinating disease of the central nervous system (CNS) was made. A further workup led to the final diagnosis of neurosarcoidosis. In a retrospective neuroradiologic assessment, an alteration compatible with a non-active demyelinating lesion in the MLF was detected on secondary imaging as a probable cause of the initial pathophysiologic finding. In this report, we aimed to highlight the unusual case of a disconjugate VOR as a distinctive VHIT pattern hinting toward a central cause of acute vertigo that clinicians should be aware of.

Changes in intracortical excitability after successful epilepsy surgery.

Interictal activity from epileptic foci may have remote effects as demonstrable by assessing brain perfusion, metabolism and excitability. So far, the effect of surgical removal of the epileptic focus on cortical networks has only rarely been addressed. This study aims at an assessment of changes in intracortical inhibition and excitability in patients undergoing successful epilepsy surgery. Twenty-two patients (12 females, 10 males, mean age 37.8 years) with identical pre- and postsurgical antiepileptic medication were investigated using focal transcranial magnetic stimulation. Motor thresholds (MT), contralateral cortical silent periods (CSP) and amplitudes of motor evoked potentials (MEP) using paired pulse paradigms were investigated both, at the focal and non-focal hemisphere before and at least 3 months after successful epilepsy surgery. The postsurgical mean MT when stimulating at the focal hemisphere was significantly higher than at the non-focal hemisphere (p=0.01). Postsurgically, the mean duration of the CSP at 120% and at 150% of MT of the non-focal hemisphere was significantly shorter than presurgically (p=0.04), and the mean MEP amplitude following paired-pulse stimulation with an interstimulus interval of 10 ms of the non-focal hemisphere was significantly lower than presurgically (p=0.03). In summary, both parameters representing inhibition and facilitation changed following epilepsy surgery; effects were statistically significant on the non-focal hemisphere. Transcranial magnetic stimulation thus gave evidence of remote effects of an epileptic focus and its surgical removal. Extended changes in excitability due to the presence or absence of an epileptic focus may be related to widespread functional impairments in patients with focal epilepsy.

Clinical characteristics in focal cortical dysplasia: a retrospective evaluation in a series of 120 patients.

Focal cortical dysplasias (FCDs) are increasingly diagnosed as a cause of symptomatic focal epilepsy in paediatric and adult patients. However, little is known about the clinical characteristics of epilepsy in these patients. In order to elucidate the clinical characteristics of their epilepsy, 120 pharmacoresistant patients including children and adults with histologically proven FCD were studied retrospectively. Age at seizure onset was analysed in the total group and compared between subgroups with different localization and different histological subtypes of FCD. The role of febrile seizures with respect to dual pathology was investigated. Seizure semiology was analysed focusing on initial seizure type and change of seizure semiology during the course of disease. Finally, transient responsiveness to antiepileptic drug therapy was studied. In the majority of patients, epilepsy began in the first 5 years of life. However, onset of epilepsy could also occur in the second or third decade until the age of 60. Age at epilepsy onset was not significantly different between temporal, extratemporal and multilobar localization of FCD. Patients without cytoarchitectural abnormalities (mild malformations of cortical development, FCD 1a according to Palmini) had significantly later epilepsy onset (P= 0.001) compared with patients with cytoarchitectural abnormalities (FCD 1b, 2a and 2b according to Palmini). In patients with additional hippocampal sclerosis (dual pathology) febrile seizures were significantly more frequently reported (P = 0.02) than in patients without dual pathology. Moreover, patients with dual pathology and febrile seizures significantly more frequently presented with severe hippocampal sclerosis (Wyler Grade 3-4) as compared with patients with dual pathology in the absence of febrile seizures (P = 0.03). First observed seizures were mainly tonic or generalized tonic-clonic. A change of seizure semiology seemed to be age-dependent and occurred between the age of >1 and 14 years. About 15.8% of the patients presented with status epilepticus during the course of disease. About 17% of the patients showed transient responsiveness (> or =1 year seizure freedom) to antiepileptic drug therapy either after initial therapy (50%) or later in the course of epilepsy (50%). Patients with FCD represent a heterogeneous group. Different age at epilepsy onset and transient responsiveness to antiepileptic drugs in approximately 17% of patients may reflect different dynamics in epileptogenicity of the underlying FCD. Dual pathology may be associated with different pathomechanisms in patients with and without febrile seizures.