Brainstem lesions with pure motor hemiparesis. Computed tomographic demonstration

Syndromes of pontine base infarction. A clinical-radiological correlation study

BACKGROUND AND PURPOSE

Although there have been sporadic reports of lacunar syndromes due to pontine base infarction, studies of clinical-radiological correlation in sufficient numbers of patients have not yet been reported.

METHODS

We studied the clinical features of 37 patients with acute infarcts that mainly involved the base of the pons and correlated the clinical syndromes with the radiological findings.

RESULTS

The clinical presentations included pure motor hemiparesis (PMH) in 17, sensorimotor stroke in 3, ataxic hemiparesis (AH) in 4, and dysarthria-clumsy hand (DA-CH) syndrome in 6 patients. Variants of AH included 1 patient with dysarthria-hemiataxia and 2 with quadrataxic hemiparesis, and in 4 patients dysarthria-facial paresis syndrome was considered a variant of DA-CH syndrome. Hypertension was the single most common and important risk factor, and the pathogenetic mechanisms of ischemia were likely to be small arterial (lacunar) occlusion or basilar atheromatous branch occlusion in most of the patients. Our clinical-radiological correlation study suggested that large lesions involving the paramedian caudal or middle pons correlate with severe hemiparesis (PMH), whereas lesions of similar size located in the paramedian rostral pons tended to produce DA-CH syndrome. Lesions producing AH were located variously but tended to spare the pyramidal tracts. The prognosis of these patients is fair or good, although residual hemiparesis remained in patients with initially severe hemiparesis.

CONCLUSIONS

Our data suggest that the various lacunar syndromes that follow pontine base infarcts reflect the balance of the involvement of the corticospinal, corticopontocerebellar, and corticobulbar tracts. Analysis of radiological findings aids in determining the clinical-anatomic correlation in patients with pontine base infarction.

Neurocysticercosis presenting to the emergency department as a pure motor hemiparesis

We report the case of a 23-year-old male who presented to the emergency department (ED) with an isolated right-sided pure motor hemiparesis (PMH). An unenhanced computed tomography (CT scan) revealed a hypodensity in the area of the left parasagittal motor strip. The patient then experienced a Jacksonian type of seizure involving his right leg and was treated with intravenous phenytoin and dexamethasone. A second CT scan performed with contrast was thought to be consistent with a cerebral abscess with surrounding white matter edema. Surgical findings were consistent with neurocysticercosis. The patient was treated with praziquantel with nearly full recovery. Worldwide, cysticercosis is the most common CNS parasite. Because of immigration from endemic areas, cysticercosis has become more common in the United States. Patients with neurocysticercosis may arrive in the ED with a wide variety of unusual presentations. In this case, the PMH syndrome was caused by a solitary lesion in the motor strip. This report describes a case of PMH due to neurocysticercosis secondary to local mass affect alone. The literature of neurocysticercosis and PMH is reviewed and the pathogenesis, clinical presentation, and therapy are discussed.

Discrete lesions in the sensorimotor control system. A clinical-topographical study of lacunar infarcts

In 50 patients with computed tomography-verified small, deep, lacunar, infarcts from a prospective stroke registry, we studied the lesion site in relationship with the clinical syndromes pure motor stroke, sensorimotor stroke and ataxic hemiparesis. Seventy per cent (95% confidence interval: 57-83%) of the lesions were located in the posterior limb of the internal capsule or adjacent paraventricular region, affecting the corticospinal tract in pure motor stroke, as well as the thalamocortical tract in sensorimotor stroke, and the cerebellar (dentato(rubro)thalamocortical and corticopontocerebellar) pathways in ataxic hemiparesis. This most frequently involved area is supplied by the anterior choroidal artery, indicating that this artery is the predominant deep, penetrating artery involved in small vessel disease causing lacunar stroke syndromes.

Irreversible respiratory failure in an achondroplastic child: the importance of an early cervicomedullary decompression, and a review of the literature

The authors report the case of a girl with achondroplasia suffering from a progressively worsening hypotonic quadriparesis. CT scan showed slight dilatation of ventricular and subarachnoid spaces, with well-defined evidence of cortical sulci and gyri. This aspect was compatible with the diagnosis of macrocrania and megalencephaly (CP being 51 cm). The foramen magnum was narrowed, the transverse diameter measuring 15 mm and the 50th percentile being, for age, 26 mm. Somatosensory evoked potentials (SEPs) revealed bilaterally prolonged interpeak latencies Erb-N13, slowing of central conduction time N13-N20 from right median nerve stimulation, and block from left median nerve. The suspicion of cervicomedullary compression was confirmed by MRI, showing a very marked stenosis with compression exerted by the odontoid process. Further, a stenotic cervical canal and optic nerves verticalization were manifest. The patient underwent neurosurgical decompression by suboccipital craniectomy and cervical-C1 laminectomy. In spite of treatment, both neurologic and respiratory problems (rapid, shallow and almost abdominal breathing) were unchanged. The girl died 4 1/2 months later. The authors emphasize the important role of SEPs in detection of cervicomedullary compression in achondroplastic children and also stress the necessity of an early surgical treatment as the only condition for possible clinical improvement and/or full recovery.

Weber's syndrome with recovery: CT demonstration of an end-zone infarction in the territory of the mesencephalic artery

Weber's syndrome is one of the classically described brainstem syndromes. The mesencephalic artery and the syndromes resulting from occlusion of its branches have been attracting increasing interest in the past few years. We present here a case of Weber's syndrome emphasizing that (1) it is one of the major syndromes deriving from infarction in the territory of the mesencephalic artery; (2) that at least two clinical patterns of Weber's syndrome may be distinguished on the basis of the presence or lack of abnormal somnolence, mental confusion, and abulia; and (3) that each one of these patterns seems to be correlated with damage to distinct zones within the general territory of the mesencephalic artery.

Lacunar transient ischaemic attacks: a clinically useful concept?

Lacunar ischaemic stroke syndromes are clinically, pathophysiologically, and prognostically distinguishable from cortical ischaemic stroke syndromes. Could cerebrovascular transient ischaemic attacks (TIAs) share similar heterogeneity? 130 patients with TIAs were prospectively studied, 71 of whom underwent carotid angiography. Symptoms were associated with a 50% or greater stenosis of the ipsilateral internal carotid artery in 36 (67%) of 54 patients with presumed cortical TIAs, but in only 1 (6%) of 17 patients with presumed lacunar TIAs (p less than 0.0001). These findings support the view that cortical TIAs are associated with ipsilateral extracranial internal carotid artery atheromatous disease, whereas patients with lacunar TIAs may have absent or insignificant large-vessel disease, and probable intracranial small-vessel disease. Accurate distinction between lacunar and cortical events may have implications for investigation and treatment of patients with TIAs.

Pediatric brain stem tumor presenting as a pure motor hemiparesis

The clinical syndrome of pure motor hemiparesis occurs with lacunar lesions in the internal capsule or in the basis pontis in hypertensive adults. It has been described in three patients with brain stem tumors of which two were children. A 3 1/2 years old boy with a brain stem tumor which presented as pure motor hemiparesis is described.

Neurocysticercosis and pure motor hemiparesis

A 49-year-old man with meningeal cysticercosis presented with a pure motor hemiparesis. Computed tomography and magnetic resonance imaging showed a capsular infarction and a suprasellar cyst with surrounding arachnoiditis. Cerebrospinal fluid analysis confirmed the diagnosis as it showed positive immunologic reactions to cysticerci. This is the first reported case of pure motor hemiparesis due to a parasitic disease of the central nervous system.

Lacunar syndromes due to brainstem infarct and haemorrhage

Nine patients with brainstem infarct and two with brainstem haemorrhage presented with pure motor stroke, pure supranuclear facial palsy, sensorimotor stroke or ataxic hemiparesis. Despite the clinical similarity with hemispheric lacunes, brainstem infarcts causing lacunar syndromes probably have a greater tendency to progress. Small brainstem haemorrhages should also be considered as a cause of lacunar syndromes and the difficulty in differentiating them from small infarcts without CT is emphasised.

Role of computed tomography in vertebrobasilar ischemia

Precise delineation of vertebrobasilar ischemia by computed tomography (CT) appears difficult due to the numerous variations in distribution of the posterior fossa arterial supply. While pontine and upper brainstem infarctions can be readily demonstrated, medullary infarction remains beyond the scope of present CT scanners. CT findings in cases of basilar artery occlusion include bilateral pontine infarction or extensive brainstem ischemia, associated with cerebellar and posterior cerebral vascular damage. Demonstration of basilar artery occlusion using routine CT is only rarely achieved. In cerebellar ischemia, CT, in conjunction with clinical syndromes, helps in the recognition of the arterial territory involved. CT provides useful guidelines for the treatment of cerebellar stroke, leading to surgery in cases of massive cerebellar infarction.