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Abstract:
Pure motor hemiplegia (PMH) is a well defined syndrome usually caused by ischemic lesions of lacunar type located either in the internal capsule or in the pons. Angiography and isotope scanning are usually normal. CT scan reveals small deep infarcts and appears to be the most reliable investigative method. The CT scan findings are described of thirty patients with PMH of rapid onset (less than 36 hours). In 29 of the 30 cases a lesion was found which could explain the PMH. Small hemorrhages (2 cm in diameter) in the posterior limb of the internal capsule were noted in two cases. Ischemic lesions were found in 27 patients, 22 patients had a single lesion (20 capsular and 2 pontine), while 5 patients had 2 lesions (2 bi-capsular, 3 capsular and pontine). Three varieties of ischemic capsular lesions were observed. We found in 15 cases a capsulo-putamine-caudate infarct (type I); in 8 cases a capsulo-pallidal infarct (type II); and in 2 cases an anterior capsulo-caudate infarct (type III). Type I corresponded to the area of the lateral lenticulostriate branches of the middle cerebral artery. Type II involved the territory of the perforating branches of the anterior choroidal artery. We suggest that type III involves the territory of the internal lenticulostriate branches of the anterior cerebral artery. Lacunes are generally linked to arterial systemic hypertension. However, only 16 of 30 patients in this series were chronically hypertensive.
Insights
Pure motor hemiplegia (PMH) is typically caused by lacunar infarcts in the internal capsule or pons. CT scans are crucial for diagnosing these small deep infarcts, with 29 of 30 patients showing identifiable lesions.
Area of Science:
- Neurology
- Radiology
- Vascular Neurology
Background:
- Pure motor hemiplegia (PMH) is a distinct neurological syndrome.
- It is commonly attributed to lacunar ischemic lesions in the internal capsule or pons.
- Conventional angiography and isotope scanning are often unremarkable in PMH.
Purpose of the Study:
- To describe the computed tomography (CT) scan findings in patients with acute pure motor hemiplegia.
- To correlate CT findings with the clinical presentation of PMH.
- To investigate the vascular territories involved in capsular infarcts causing PMH.
Main Methods:
- Retrospective analysis of CT scans from 30 patients presenting with rapid-onset PMH (within 36 hours).
- Detailed description of lesion locations, sizes, and types (ischemic vs. hemorrhagic).
- Classification of ischemic capsular lesions into three types based on anatomical location.
Main Results:
- CT scans identified a causative lesion in 29 out of 30 patients.
- Ischemic lesions were present in 27 patients; 22 had single lesions (20 capsular, 2 pontine), and 5 had multiple lesions.
- Three types of capsular infarcts were observed: capsulo-putamine-caudate (Type I, n=15), capsulo-pallidal (Type II, n=8), and anterior capsulo-caudate (Type III, n=2).
- Two patients had small hemorrhages in the internal capsule.
- Only 16 of 30 patients had a history of chronic hypertension.
Conclusions:
- CT scanning is the most reliable method for diagnosing the underlying lesions in pure motor hemiplegia.
- Lacunar infarcts, particularly in the internal capsule, are the primary cause of PMH.
- The identified infarct types suggest involvement of specific cerebral artery territories (MCA, ACA, and anterior choroidal artery).