Capsular ataxic hemiparesis

Déjerine-Roussy syndrome presenting with atypical involuntary movements

The Déjerine-Roussy syndrome is caused by a stroke in the posterior lateral nuclei of the thalamus. It has a 17 to 18% prevalence after a stroke involving the inferior lateral thalamus. It is characterized by superficial hemianesthesia, allodynia, severe paroxysmal pain, and choreoathetoid movements in the limbs on the paralyzed side. A posterior lateral thalamic lesion can present with ataxia hemiparesis contralateral to the side of the lesion. We reported a case of a 65-year-old, diabetic and hypertensive male who presented with sudden onset of superficial hemianesthesia, allodynia, severe and paroxysmal pain on the right side of the body with choreoathetoid movements in the upper limb, along with slurred speech, and unsteadiness while walking.

Rehabilitation Course and Specification of Dysmetria of a Patient With Ataxia, Dysmetria, and Hemiparesis After a Stroke in the Corona Radiata: A Case Presentation

We present a case of a patient with ataxia, dysmetria, and hemiparesis after a stroke in the corona radiata. The patient had an excellent clinical course with near resolution of symptoms in 2 and a half weeks and returned back to work full duty and full time a couple of weeks later. We use videos of several neurologic tests to demonstrate and characterize the dysmetria. Interestingly, a key characteristic of the dysmetria appears to be different from that seen in patients with dysmetria arising from a cerebellar, thalamic, or pontine lesion. We propose a possible neurophysiologic mechanism-damage to and redundancy of part of the corticopontine portion of the cerebellar circuit located in the corona radiata-respectively responsible for this condition and recovery. We also discuss how a simple noninvasive study of patients with ataxia and dysmetria secondary to corona radiata, thalamic, pontine, and possibly other brain lesions may be helpful in elucidating the contribution of pontocerebellar fibers and other structures to motor control.

LEVEL OF EVIDENCE

V.

Stroke Subtype—Ataxic Hemiparesis

Ataxic hemiparesis is a lacunar syndrome of ipsilateral corticospmal and cerebellar- like dysfunction due to supratentorial and brainstem lesions We studied 22 patients with ataxic hemiparesis resulting from brain lesions at three locations: capsular-corona radiata, thalamic, and pontine with regard to (1) their manifestations, (2) the degree and rate of recovery at 12 weeks as measured on the modified Rankm Scale, and (3) factors that may influence recovery The mean age was 67 years. Symptoms and signs were similar in all three groups except qualitative differences observed in the pontine subgroup and to a lesser extent in the thalamic group Age, gender, lateralization, and location were not associated with initial severity. and had no influence on recovery. Twenty (91%) of the 22 patients were in Rankm grades 3-5 at onset, and at 12 weeks only two remained. In this study initial severity and outcome were positively corre lated, and ataxic hemiparesis augurs well with recovery. Key Words: Ataxic hemi paresis— Capsular ataxic hemiparesis—Thalamic ataxic hemiparesis—Pontine ataxic hemiparesis—Rankm Scale—Lacunar syndromes

Ataxia in patients with brain infarcts and hemorrhages

Gait and limb incoordination and ataxia are most often found in patients with brainstem and cerebellar infarcts and hemorrhages. Lesions involving the thalamus and the deep portions of the cerebral hemispheres also may cause ataxia accompanied by weakness and sensory symptoms. Patients who have lesions in the lateral medulla and inferior cerebellum often topple, lean, or veer when attempting to sit, stand, or walk. They list to the side or abruptly veer when walking. The affected limbs are often hypotonic. In pontine lesions, ataxia is accompanied by weakness and pyramidal tract signs as part of an ataxic hemiparesis syndrome. In lesions affecting the superior cerebellum and the brachium conjunctivum, limb dysmetria and overshoot and dysarthria predominate and gait ataxia is absent or slight and transient. Infarcts affecting the thalamus can cause gait instability and astasia with ataxia. Lateral thalamic lesions are characterized by hemisensory symptoms, extrapyramidal limb postures and dysfunction, and gait ataxia. Lesions that affect the posterior limb of the internal capsule and its afferent and efferent projections may also cause an ataxic hemiparesis syndrome, often with accompanying hemisensory abnormalities.

Cerebrocerebellar system and Arnold's bundle - A tractographic study: preliminary results

The cerebellum, traditionally considered a structure involved in balance and movement control, was more recently recognized as important in cognitive, emotional and behavioral functions. These functions appear to be related to the more recent parts of the cerebellum that belong to the cerebrocerebellar system. One of the key segments of this system is the (pre)fronto-[penduncule]-pontine projection that represents the Arnold's bundle. Diffusion tensor imaging and tractography (DTI-TR) has permitted in vivo virtual dissection of white matter tracts, including those of the cerebellar.

OBJECTIVE

To study the fronto-[peduncule]-pontine projection (Arnold's bundle), with DTI-TR.

METHODS

Ten normal subjects were included (mean age 30 years). Standard acquisitions in three planes were obtained with a 1.5T GE Signa Horizon scanner, complemented with DTI acquisitions. Post-processing and analysis was performed using an ADW 4.3 workstation running Functool 4.5.3(GE Medical Systems). A single ROI was placed on the medial third of the cerebral peduncle base, considered the site of convergence of the fibers of Arnold's bundle, bilaterally.

RESULTS

Twenty tractograms were obtained. All were constituted by a significant number of fibers in correspondence to the frontal lobe, and part of them anterior to the coronal plane at the anterior commissure, which characterizes them as associated to the prefrontal region.

CONCLUSIONS

For the first time, frontal lobe related projections were systematically revealed with DTI-TR seeded from cerebral peduncle base ROIs. They showed anatomic coherence with Arnold's bundle, which includes the prefrontopontine segment of the cortico-ponto-cerebellar path, one of the components of the cerebrocerebellar system, acknowledged as fundamental for non-motor functions such as cognition, emotion and behavior.

Ataxic hemiparesis: critical appraisal of a lacunar syndrome

BACKGROUND AND PURPOSE

Ataxic hemiparesis is a well-recognized lacunar syndrome involving homolateral ataxia with accompanying corticospinal tract impairment. Despite 30 years of clinical experience there continues to be some doubt as to the defining clinical characteristics, precise neuroanatomic localization of the syndrome, and etiologic mechanisms.

METHODS

We now present 45 new cases that have been analyzed for clinico-radiologic correlation and etiology. Also, all published cases from the English literature known to the authors are reviewed.

RESULTS

We found that the clinical syndrome of ataxic hemiparesis accurately predicts a small deep infarction, generally in the pons or internal capsule. Sensory loss is highly associated with a capsular localization. We found that 47% of the cases were attributed to small-vessel disease, 11% to cardioembolism, and only 7% to artery-to-artery embolism (all in the basilar artery); 1 case was attributed to thrombocytosis, 1 to multiple sclerosis, and the rest either had negative or incomplete evaluation. Approximately two thirds of the infarctions occurred in patients with neuroimaging evidence of other ischemic brain lesions.

CONCLUSIONS

Ataxic hemiparesis is a distinct clinical syndrome that accurately predicts a small deep infarction, most commonly in the pons or internal capsule. Only sensory loss accurately predicts a capsular localization. Etiology in nearly half of the cases can be attributed to small-vessel disease. Furthermore, ataxic hemiparesis appears to be a good marker for generalized asymptomatic cerebrovascular disease.

Dissociation in the neural control of single-joint and multi-joint movements in the thalamic ataxia syndrome

We report a patient presenting with a right thalamic ataxia syndrome following a hemorrhage located in the left lateral and posterior thalamus. We investigated the fast goal-directed movements of the wrists (single-joint movements) and the fast pointing movements in the upper limbs (multi-joint movements). On the right side, single-joint movements were markedly hypermetric and characterized by an asymmetry in kinematics, an abnormality of ballistic movements which is considered to be a fundamental cerebellar disorder. By contrast, rapid multi-joint movements were only very slightly impaired. These results suggest that ballistic movements of the wrist are under the strong influence of the cerebello-thalamo-cortical pathway, while rapid pointing multi-joint movements in upper limb are mostly influenced by another pathway emerging from the lateral cerebellum, possibly the dentato-rubral or the dentato-reticular projections in the brainstem. The roles of these neuroanatomical pathways in the control of fast single-joint and multi-joint movements are discussed.

Parieto-cerebellar loop impairment in ataxic hemiparesis: proposed pathophysiology based on an analysis of cerebral blood flow

Sixteen stroke patients suffering from ataxic hemiparesis syndrome were studied with regional cerebral blood flow measured by 133-Xenon inhalation technique (12 patients) and by SPECT (HMPAO) (9 patients). The causative lesions (hematoma in 7 and infarct in 9), unilateral in 15 patients and bilateral in 1, were located in the posterior two-thirds of the corona radiata, thalamo-capsular and subthalamus regions, or cerebral peduncle. Ataxia of the cerebellar type was unilateral in 15 patients and bilateral in 1 with similar, deep, bilateral causative lesions. Four patients presented some characteristics of proprioceptive ataxia (mixed ataxia). Associated cognitive disturbances were present in 9 patients and absent in 7. Eleven of the 12 subjects studied by 133-Xenon inhalation technique showed limited centro-parietal hypoperfusion, mainly in the inferior parietal lobule, ipsilateral to the causative lesion and bilaterally in the patient with bilateral lesions and ataxia. Ipsilateral hypoperfusion was confirmed in 7/9 patients studied by SPECT, which also demonstrated contralateral cerebellar hypoperfusion in 4 patients. These findings suggest that ataxic hemiparesis syndrome results from functional depression (diaschisis) consequent to the interruption at many levels of an "inferior parietal associative cortex-cerebellar anterior lobe" circuit.

Neurinoma of the third, fourth, and sixth cranial nerves: a survey and report of a new fourth nerve case

A rare case of trochlear nerve neurinoma is described. Including this case, the number of reported intracranial tumors arising from the sheaths of the third, fourth, and sixth cranial nerves is 38. By site and relationship to the nerve segment, they fall into three groups: cisternal, cisternocavernous, and cavernous. In cisternal tumors of the third and sixth nerves, paresis of the nerve hosting the tumor is the unique nerve deficit; by contrast, in those of the fourth nerve, paresis of the trochlear nerve can be absent and that of the third nerve present. In the latter tumors, a peculiar ataxic hemiparesis syndrome is produced by midbrain compression. Cisternocavernous neurinomas often cause symptoms of intracranial hypertension, while cavernous neurinomas bring about two clinical features: paresis of one or more nerves of the cavernous sinus and a clinicoradiological orbital apex syndrome. At surgery, generally cisternal neurinomas are totally removed and the nerve source of the tumor identified; in cisternocavernous and cavernous neurinomas, total removal of tumor and identification of the parent nerve have been reported in only half of the cases. In the majority of parasellar neurinomas, clinical differences can be found between those arising from the nerves governing eye movement and those arising from the gasserian ganglion.

Hemiataxia-hypesthesia: a thalamic stroke syndrome

Six patients had isolated hemiataxia and ipsilateral sensory loss, as a manifestation of thalamic infarction in the thalamogeniculate territory. Acute hemiataxia-hypesthesia was not found in 1075 other patients from the Lausanne Stroke Registry who were admitted during the same period. Stroke onset was progressive in five patients and immediately complete in one. Five patients had an objective sensory loss. In two patients this affected light touch, pain and temperature sense, and in another three light touch, pain temperature, position and vibration sense. One patient had a purely subjective sensory disturbance. The sensory deficit cleared or was clearing although the ataxia persisted in all patients. On lesion mapping on CT or MRI, all patients had involvement of the lateral part of the thalamus (ventral posterior nucleus and ventral lateral nucleus). The presumed causes of stroke were cardioembolism in one patient, posterior cerebral artery occlusion in one patient and meningovascular syphilis in one patient, hypertensive small vessel disease in two patients, and undetermined in one patient. Hemiataxia-hypesthesia is a new stroke syndrome involving the perforating branches to the lateral thalamus, but in which small vessel disease may not be the leading cause.

The anterior choroidal artery does not supply the corona radiata and lateral ventricular wall

BACKGROUND AND PURPOSE

We sought first to characterize the clinical syndromes of patients found to have angiographic, computed tomographic, or magnetic resonance imaging scan indexes of anterior choroidal artery territory infarction and then to determine the frequency of involvement of the periventricular corona radiata in such patients.

METHODS

Sixteen patients were selected based on angiographically, or surgically, documented occlusion of the anterior choroidal artery or based on infarcts whose minimal lesions included the anterior choroidal territory as defined by Kolisko and Beevor. We mapped the lesions using the templates of the Matsui and Hirano atlas and entered them into a computer using a program allowing overlapping diagrams of the cases.

RESULTS

The anatomic distributions were fairly uniform, all involving the lower portion of the posterior limb of the internal capsule, the medial pallidum (75% of cases), cerebral peduncle in 44%, thalamus in 37%, and the medial temporal lobe in 38%. None extended outside these areas to include the upper corona radiata. The clinical picture corresponded to the well-established neurological syndrome featuring motor deficits with varying degrees of visual field and sensory impairments. Only two showed hypesthetic ataxic hemiparesis.

CONCLUSIONS

Our findings indicate that the syndrome of anterior choroidal artery infarction is fairly uniform; ataxic hemiparesis occurs infrequently; and lesions in the lateral ventricular wall and the corona radiata are not part of the territory supplied by the anterior choroidal artery.

Reversible postictal ataxic hemiparesis

Ataxic hemiparesis (AH) is a clinical entity in which minimal pyramidal weakness is associated with same-sided motor ataxia. It may be caused by a lesion of the pons or of cerebro-cerebellar and corticospinal fibers in other areas. Associated symptoms help in the clinical localization of a syndrome that has to be differentiated from lobar ataxias (frontal, parietal lobe), sensory ataxia accompanying spinal cord, corticospinal weakness and ataxic neuropathy. We report 3 cases of AH caused by a lesion in the contralateral cerebral cortex: 2 were cases of postictal seizure while the third patient had left ataxic hemiparesis, left focal motor seizures and cortical memory loss. All 3 patients recovered within 7 days. AH as a postictal phenomenon has not previously been reported.

Clinical-computed tomographic correlations of lacunar infarction in the Stroke Data Bank

Lacunar stroke was diagnosed in 337 (26%) of the 1,273 patients with cerebral infarction among the 1,805 total in the Stroke Data Bank. We analyzed the 316 patients with classic lacunar syndromes. Among these, 181 (57%) had pure motor hemiparesis, 63 (20%) sensorimotor syndrome, 33 (10%) ataxic hemiparesis, 21 (7%) pure sensory syndrome, and 18 (6%) dysarthria-clumsy hand syndrome. No striking differences were found among the risk factors for the lacunar subtypes, but differences were found between lacunar stroke as a group and other types of infarcts. Compared to 113 patients with large-vessel atherosclerotic infarction, those with lacunar stroke had fewer previous transient ischemic attacks and strokes. Compared to 246 with cardioembolic infarction, patients with lacunar stroke more frequently had hypertension and diabetes and less frequently had cardiac disease. We found a lesion in 35% of the lacunar stroke patients' computed tomograms, with most lesions located in the internal capsule and corona radiata. The mean infarct volume was greater in patients with pure motor hemiparesis or sensorimotor syndrome than in those with the other lacunar stroke subtypes. In patients with pure motor hemiparesis and infarcts in the posterior limb of the internal capsule, there was a correlation between lesion volume and hemiparesis severity except for the few whose infarct involved the lowest portion of the internal capsule; in these patients severe deficits occurred regardless of lesion volume. Taken together, the computed tomographic correlations with the syndromes of hemiparesis showed only slight support for the classical view of a homunculus in the internal capsule.

Capsular ataxic tetraparesis

A 42-year-old man with ataxic tetraparesis is reported. Computerized tomography showed bilateral and symmetrical lacunar infarcts at the junctions of the posterior limb of the internal capsule and the corona radiata. Previously this clinical syndrome had been reported only with a lesion in the pons.

The dysarthria-clumsy hand syndrome: a distinct clinical entity related to pontine infarction

Using magnetic resonance imaging, we studied 6 patients with the dysarthria-clumsy hand syndrome. All were found to have pontine infarctions contralateral to the symptomatic side. Clinically, these patients exhibited dysarthria; "clumsiness," characterized by dysmetria, dysrhythmia, dysdiadochokinesia and sometimes truncal and gait ataxia; and mild ipsilateral weakness. Previous clinical-anatomical correlations for this syndrome are limited by inconsistencies in clinical diagnostic criteria and low-resolution imaging methods. In our patients, and in a review of the literature, the overwhelming majority of patients with the dysarthria-clumsy hand syndrome had pontine infarcts. We conclude that if rigid clinical criteria are used, the label of the dysarthria-clumsy hand syndrome predicts a lesion in the contralateral basis pontis.

Capsular hypesthetic ataxic hemiparesis

Twenty-three patients with hypesthetic ataxic hemiparesis underwent computed tomography or magnetic resonance imaging. Twenty-two patients had infarcts of lacunar or slightly larger size in the contralateral posterior limb of the internal capsule. In 15 patients the infarct extended superiorly into the adjacent paraventricular region, and in seven it extended into the lateral thalmus. In eight patients the infarct was limited to the posterior limb of the internal capsule, and in only two patients was an ipsilateral to capsular pontine lacune found. Despite a location similar to that of pure motor and pure sensory lacunar stroke, hypesthetic ataxic hemiparesis correlates with larger infarcts, most often located in the posterior medial superior territory of the anterior choroidal artery. Some infarcts appeared to be localized immediately posterolateral to this region, in the posterior cerebral artery territory. The presence and extent of infarction is better detected by the addition of magnetic resonance imaging to computed tomography.

Magnetic resonance imaging of ataxic hemiparesis localized to the corona radiata

A 61-year-old woman developed right hemiparesis with homolateral cerebellar-type ataxia. Computed tomography and magnetic resonance imaging demonstrated left corona radiata lesions, not present on magnetic resonance imaging 1 year earlier. No brainstem lesions were identified, suggesting that ataxic hemiparesis can result from lesions in the corona radiata.

Hypesthetic ataxic hemiparesis in a thalamic lacune

Right hemiparesis with an ipsilateral hypesthesia and ataxia developed in a 57-year-old man. Magnetic resonance imaging showed a left thalamic lacune bordering the medial portion of the posterior limb of the internal capsule. This finding implicated some pathogenetic mechanism of ataxic hemiparesis.

Thalamic astasia: inability to stand after unilateral thalamic lesions

Inability to stand in the absence of motor weakness or marked sensory loss is usually considered to reflect midline cerebellar disease. However, the 15 patients reported here had astasia related to unilateral thalamic lesions, documented by autopsy and computed tomography in 2 patients and by computed tomography in 13. The lesions, including infarction (6), hemorrhage (7), and tumor (2), involved primarily the superoposterolateral portion of the thalamus, but spared the rubral region. Alert, with normal or near-normal strength on isometric muscle testing and a variable degree of sensory loss, the patients could not stand and 7 of them could not sit up unassisted. They fell backwards or toward the side contralateral to the lesion. They appeared to have a deficit of overlearned motor activity of an axial and postural nature. In the vascular cases, the deficit improved in a few days or weeks. However, these patients had a tendency to sustain falls during the rehabilitation period.

Somatosensory evoked potentials in lacunar syndromes of pure motor and ataxic hemiparesis

Syndromes of hemiparetic lacunar infarction include pure motor hemiparesis and ataxic hemiparesis. Twelve such patients were evaluated with somatosensory evoked potentials. Potentials were delayed or absent in all 4 patients with ataxic hemiparesis and in 1 of 8 patients with pure motor hemiparesis. Unlike pure motor hemiparesis, ataxic hemiparesis appears to be associated with abnormal somatosensory evoked potentials. These abnormalities suggest that disturbance of afferent pathways are important in ataxic hemiparesis.

Neurophysiological analysis of ataxia in capsular ataxic hemiparesis

A quantitative analysis of ataxia and the readiness potential were studied in four cases of ataxic hemiparesis resulting from a small infarct in the posterior limb of the internal capsule. The ataxia appeared to be the result of involvement of the corticopontine tract originating from the precentral region (areas 4 and 6) at this level. The voluntary movements of the affected limbs were characterized by slowness and irregularity similar to those seen in cerebellar ataxia. The weakness per se was not such that it could account for the ataxia. The dentato-rubro-thalamo-cortical system did not appear to be significantly involved on the basis of normal readiness potentials.

Ataxic hemiparesis with reductions of ipsilateral cerebellar blood flow

Regional cerebellar blood flow was measured in a patient with left-sided ataxic hemiparesis, using single-photon emission computed tomography and N-isopropyl-p-[123I]Iodoamphetamine. X-ray computed tomography revealed a small infarct in the paramedian portion of the right upper basis pontis. Blood flow was markedly reduced in the contralateral cerebellar hemisphere corresponding to the side of ataxia. The present study emphasizes the value of the three-dimensional functional imaging of the cerebellum to investigate the responsible lesion for ataxia and to study function of the cerebro-cerebellar circuits.

Vascular ataxic hemiparesis: a prospective clinical and CT study

Ataxic hemiparesis is a relatively frequent clinical syndrome in which motor and cerebellar deficits on the same side are associated. A prospective study conducted on 27 patients who displayed these vascular symptoms confirms that the areas crucial to the onset of this syndrome are the capsular region (posterior limb-corona radiata) and the upper basis pontis.

Ataxic hemiparesis syndrome: clinical and CT study of 20 new cases and review of the literature

20 new cases of ataxic hemiparesis syndrome (AHS) are reported and the findings compared with those of published cases. AHS may be due to lesions either of the brainstem or of supratentorial structures, where motor fibers run together with the cerebro-cerebellar pathways. Specific syndromes related to the lesion site cannot be identified from the clinical signs. Ischemic infarct is the most frequent cause of the syndrome, but hemorrhagic, neoplastic and demyelinating lesions have also been reported.

Hypesthetic-ataxic-hemiparesis in thalamic hemorrhage

Acute onset hypesthetic-ataxic-hemiparesis is described in two hypertensive patients. Computed tomography (CT) showed an area of increased attenuation consistent with blood in contralateral thalamus. The pathophysiologic implications of the cerebellar and pyramidal system in thalamic hemorrhage is discussed.

Perforating branches of the middle cerebral artery. Microanatomy and clinical significance of their intracerebral segments

Perforating branches of the middle cerebral arteries (MCA) were examined on the forebrain hemispheres of fourteen human brains. It was noticed that their intracerebral segments arose from the MCA main trunk, and its terminal and collateral (cortical) branches. They terminated in certain parts of the basal ganglia and internal capsule. The course, direction, shape, diameters and branches of these segments were examined in detail. Classification of all the vessels was made according to caliber. It was concluded that the size of lacunar infarcts depends on the caliber and ramification zone extent of the occluded perforating vessels. Diameters of the intracerebral segments of vessels ranged from 80 to 840 microns, of their terminal branches from 80 to 780 microns, and of the collateral branches from 50 to 400 microns. The average size of the ramification zone was: 41.6 X 15.5 mm for the entire perforating artery; 37.9 X 15.5 mm for the intracerebral segment; 23 X 13 mm for the terminal branches; 8.9 X 5.5 mm for larger collateral branches; and 2.6 X 1.4 mm for the smallest branches.

X-ray computed tomography (CT) study of small, deep and recent infarcts (SDRIs) of the cerebral hemispheres in adults. Preliminary and critical report

The evolution of CT signs of small, deep infarcts of the cerebral hemispheres in thirty adults, in the first five weeks, has been retrospectively studied. The relevant literature has been reviewed and an attempt has been made to present a synthesis, accompanied by a commentary. It is impossible now to give the frequency of each type of evolution, but the main data are as follows: The shortest delay of visibility of an hypodense area is about 17 to 19 h, but at 27 h the densities may still be normal. The evolution of the hypodense area is also variable: after a minimum attenuation is reached--at approximately 72 h--there is a risk of "fogging effect", which reduces the visibility of ischemic lesions; it could be seen from the end of the 1st week to the beginning of the 4th, but its frequency and its duration have yet to be better determined. In our series, contrast enhancement has been found in the gray matter of the basal ganglia between the 8th and the 22nd days--but according to some observations recorded in the literature, it may be found from the second to the twenty sixth day--and there was no obvious contrast enhancement in the white matter. The significance of the evolving CT signs is discussed in connection with the clinical applications, principally in the management of these patients, and with the attempts to correlate the clinical and CT findings.

Ataxic hemiparesis: further CT confirmation of an old localizing hypothesis

4 cases of ataxic hemiparesis syndrome are supported by CT proof of a lesion confined to the posterior and superior part of the internal capsule, near the corona radiata. The site of lesion is usually held to be the basis pontis and rostral midbrain. We intend to furnish further evidence in support of an old hypothesis incriminating the corona radiata-internal capsule.

Ataxic-hemiparesis, localization and clinical features

Five additional cases of ataxic-hemiparesis are reported. In 3 cases, computed tomography showed an area of decreased attenuation in the posterior limb of the internal capsule, and in 1 case, 2 areas of attenuation in the corona radiata. A review of previously reported cases suggest that brainstem ataxic-hemiparesis may be separated from supratentorial forms of ataxic-hemiparesis by the presence of nystagmus, dysarthria, cranial neuropathy, and the absence of sensory abnormality.

Ataxic tetraparesis from lacunar infarction in the pons

A 45-year-old woman with hypertension suffered four episodes of right hemiparesis and two attacks of left hemiparesis, within seven months. On examination she showed weakness and cerebellar ataxia of all four limbs. Computed tomography demonstrated a radiolucent area in the base of the pons, consistent with lacunar infarction.

Hemiataxia and crural hemiparesis following capsular infarct

Two patients presenting with hemiataxia and hemiparesis on the same side are described. Both had CT scan evidence of an infarct located in the posterior limb of the contralateral internal capsule.