Search results for "Flocculus"
showing 5 items of 5 documents
Anatomical correlates of ocular motor deficits in cerebellar lesions
2009
Humans are able to stabilize the images of moving targets on the retina by means of smooth pursuit eye movements. After the pontine level, all smooth pursuit pathways pass through the cerebellum. Previous animal studies gave evidence that two specific lesion sites within the cerebellum cause smooth pursuit disorders: those of the flocculus/paraflocculus and the vermis including lobule VI, VII, the uvula and the deep cerebellar nuclei. To date, there have been only a few lesion studies in patients with smooth pursuit disorders that do not allow direct comparison with a control group. In the present study, new lesion mapping techniques determined which cerebellar structures were involved in p…
Functional brain imaging of peripheral and central vestibular disorders.
2008
This review summarizes our current knowledge of multisensory vestibular structures and their functions in humans. Most of it derives from brain activation studies with PET and fMRI conducted over the last decade. The patterns of activations and deactivations during caloric and galvanic vestibular stimulations in healthy subjects have been compared with those in patients with acute and chronic peripheral and central vestibular disorders. Major findings are the following: (1) In patients with vestibular neuritis the central vestibular system exhibits a spontaneous visual-vestibular activation–deactivation pattern similar to that described in healthy volunteers during unilateral vestibular sti…
Incidence and anatomy of gaze-evoked nystagmus in patients with cerebellar lesions.
2011
Background: Disorders of gaze-holding—organized by a neural network located in the brainstem or the cerebellum—may lead to nystagmus. Based on previous animal studies it was concluded that one key player of the cerebellar part of this gaze-holding neural network is the flocculus. Up to now, in humans there are no systematic studies in patients with cerebellar lesions examining one of the most common forms of nystagmus: gaze-evoked nystagmus (GEN). The aim of our present study was to clarify which cerebellar structures are involved in the generation of GEN. Methods: Twenty-one patients with acute unilateral cerebellar stroke were analyzed by means of modern MRI-based voxel-wise lesion-behavi…
The topographic diagnosis of acquired nystagmus in brainstem disorders.
2002
Evidence is presented for a clinical classification of central vestibular syndromes according to the three major planes of action of the vestibulo-ocular reflex (VOR): yaw, pitch, and roll. The plane-specific vestibular syndromes are determined by ocular motor, postural, and perceptual signs. Yaw plane signs are horizontal nystagmus, horizontal past pointing, rotational and lateral body falls to the right or to the left, and horizontal deviation of perceived straight-ahead. Pitch plane signs are upbeat/downbeat nystagmus, forward/backward tilts and falls, and upward or downward deviations of the perceived horizontal. Roll plane signs are torsional nystagmus, skew deviation, ocular torsion, …
18F-fluorodeoxyglucose hypometabolism in cerebellar tonsil and flocculus in downbeat nystagmus.
2006
A patient with downbeat nystagmus was examined by F-fluorodeoxyglucose-positron emission tomography once while off and twice while on successful treatment with 4-aminopyridine. All positron emission tomography scans of the patient showed a reduced cerebral glucose metabolism bilaterally in the region of the cerebellar tonsil and flocculus/paraflocculus when compared with a normal database of the whole brain. An additional region-of-interest analysis revealed that 4-aminopyridine treatment lessened the hypometabolism. This finding supports the hypothesis that the cerebellar tonsil and (para-) flocculus play a crucial role in downbeat nystagmus. The hypometabolism might reflect reduced inhibi…