The mechanism of ipsilateral ataxia in lacunar hemiparesis: SPECT perfusion imaging.

BACKGROUND AND PURPOSE: Although ataxic hemiparesis is a common lacunar syndrome, the precise mechanism underlying hemiataxia is not clear. We attempted to identify ataxia-related, cerebral blood flow changes in patients presenting with ataxic hemiparesis after acute capsular infarct. METHODS: We used 99mTc-ECD brain perfusion single-photon emission computed tomography to evaluate regional cerebral blood flow in 12 patients with ataxic hemiparesis caused by capsular infarct, and we compared the regional blood flow of these patients with that of 11 patients with pure motor hemiparesis caused by similar lesions. RESULTS: The ipsilateral red nucleus blood flow was significantly decreased in the ataxic hemiparesis patients, whereas the ipsilateral red nucleus blood flow was increased in the pure motor hemiparesis patients. Crossed cerebellar diaschisis (decreased contralateral cerebellar blood flow) was seen in ataxic hemiparesis patients; similarly, it was seen in pure motor hemiparesis patients. CONCLUSIONS: Our findings suggest that ataxia in hemiparetic patients with capsular infarct can be caused by ipsilateral red nucleus dysfunction secondary to cortico-rubral pathway disruption at the internal capsule.

Rubral lateropulsion due to vertebral artery dissection in a patient with Klippel-Feil syndrome.

BACKGROUND: Neurologic deficits in patients with Klippel-Feil syndrome usually are attributed to direct compression of neuronal structures or hypoperfusion secondary to compression of the vertebral arteries by bony abnormalities. OBJECTIVE: To describe a 38-year-old woman with known Klippel-Feil syndrome who developed lateropulsion. RESULTS: The results of magnetic resonance imaging were consistent with rubrothalamic stroke. The cerebral angiogram confirmed vertebral artery dissection at the level of her previously observed bony abnormality. CONCLUSIONS: Hypermobility adjacent to fused vertebrae subjects the vertebral artery to increased shear forces. Thus, Klippel-Feil syndrome may be a predisposing factor for vertebral artery dissection. Moreover, to our knowledge, this case represents the second known case of rubral lateropulsion.

['Rubral' tremor after vascular thalamic lesions]. / Temblor 'rúbrico' tras lesiones vasculares talámicas.

INTRODUCTION: The appearance of tremor after thalamic lesions is well-known but infrequent. Amongst the semiological varieties of thalamic tremors, a particularly uncommon type--which is extremely incapacitating owing to its great amplitude, appearance during action and poor therapeutic response--is the so-called rubric or mesencephalic tremor. CLINICAL CASES: We present four cases, of tremor with the semiological characteristics of rubric tremors after thalamic lesions of ischaemic or haemorrhagic origin. We review the relevant literature. DISCUSSION: The rubric tremor has been said to have its physiopathological origin in a lesion of the nigro-striate via and the efferent cerebellar vias at some point of the mesencephalic or subthalamic path, often without direct involvement of the red nucleus. CONCLUSIONS: The presentation of this type of tremor due to lesions which do not effect the red nucleus and the mesencephalum show the unsuitability of the name.

Tremor due to stroke.

We report on four patients with unilateral tremor stemming from cerebrovascular accidents. In two patients with proven lesions of the thalamus, the tremor was irregular and, in addition, there was dystonic posturing of the affected arm. Tremor and dystonic posturing had appeared after the stroke. In the other two patients tremor had occurred immediately at the onset of the stroke and lasted only a few days. The tremors were of small amplitude and high frequency, and lesions could not be found on CT or MRI in these two patients. None of our patients showed signs of the so-called rubral tremor.

[Alternate red nucleus syndrome (Claude variant). Apropos of a case report]. / Syndrome alterne du noyau rouge (variante de Claude). A propos d'une observation.

The authors describe a case of Claude's syndrome corresponding to a third cranial nerve palsy with contralateral cerebellar ataxia, due to a red nucleus softening. They review the different varieties of red nucleus syndromes and their usual causes.

Rubral tremor: clinical features and treatment of three cases.

Rubral tremor is characterized by a slow coarse tremor at rest that is exacerbated by postural adjustments and by guided voluntary movements. Some authorities have questioned whether it should be regarded as a distinct clinical entity. We observed three cases of rubral tremor following stroke and studied the movements by videotape recordings. The tremors were very similar in the three cases, and all showed plastic rigidity and dystonic posturing of the affected limbs. Rehabilitation difficulties out of proportion to the motor deficit were present, but all three patients responded favourably to treatment with levodopa-carbidopa. Lesions of the superior cerebellar peduncle, midbrain tegmentum or posterior part of the thalamus may cause this peculiar tremor, and it is probable that lesions of the red nucleus itself are not crucial for its production. The similarity of the clinical features and management problems of these cases suggests that it is valuable to regard rubral tremor as a specific clinical syndrome.

[Arteries of the human thalamus. II. Arteries and paramedian thalamic territory of the communicating basilar artery]. / Les artères du thalamus humain. II.--Artères et territoires thalamiques paramédians de l'artère basilaire communicante

The basilar communicating artery (or mesencephalic artery) gives off more often one than two paramedian thalamic arteries. The paramedian territory, infero-medial, has a variable extent. It can include the polar territory when the polar artery does not exist. The paramedian artery arises as often from the controlateral basilar communicating artery than from the ipsilateral one. One basilar communicating artery may so have a very extensive bilateral territory.