Evaluation of Anterior Cerebral Artery Flow Abnormalities on Transcranial Doppler Ultrasonography

BACKGROUND: Anterior cerebral artery (ACA) flow abnormalities on a transcranial Doppler ultrasonography (TCD) represent various conditions, which include hyperemic collateral to the ipsilateral middle cerebral artery (iMCA) or contralateral internal carotid artery (cICA) pathology, and ipsilateral anterior cerebral artery (iACA) stenosis. However, studies related to these conditions have rarely been done. We evaluated the hemodynamic significance of ACA flow abnormalities on TCD without angiographic information. METHODS: We analyzed TCD records, which were recruited consecutively during a 10-month period in our laboratory. ACA abnormalities on TCD were defined as follows: 1) mean flow velocities (mFV) of ACA>80 cm/sec; 2) ipsilateral mFV ACA/MCA> 1.2; 3) anterior cerebral artery veloci-ty ratios (ACAVR)> 1.34. We then correlated TCD patterns with a magnetic resonance angiography (MRA) or trans-femoral cerebral angiography (TFCA). RESULTS: Thirty-five patients were recruited to participate in this study. Based on MRA or TFCA, we found 4 patterns of vascular status which could explain the ACA abnormalities on the TCD. The iMCA pathology was demonstrated in 14 cases, cICA pathology in 11 cases, iACA stenosis in 3 cases, and cACA hypoplasia in 5 cases. Eight cases did not show any vascular pathology. CONCLUSIONS: ACA flow abnormalities should be evaluated with absolute flow velocity indicies, as well as other indexes, which mostly signify hyperemic collateral flow to the iMCA or cICA steno-occlusion. (J Korean Neurol Assoc 19(4):349~353, 2001)

A Case of Mitochondrial Neurogastrointestinal Encephalomyopathy

Mitochondrial neurogastrointestinal encephalomyopahty (MNGIE) is a rare disorder and is clinically characterized by ophthalmoparesis, peripheral neuropathy, leukoencephalopathy, gastrointestinal symptoms with intestinal dysmotility, and histologically abnormal mitochondria in muscle. A 32-year-old female showed external ophthalmoparesis, bilateral ptosis, quadriparesis, and sensory change below both ankle joints. Level of serum lactic acid was highly increased. The brain MRI showed diffusely increased signal intensity in the centrum semiovale and white matter. Electron microscopic finding showed paracrystalline inclusions in mitochondria of a few muscle fibers. (J Korean Neurol Assoc 19(3):309~312, 2001)

A Case of Bilateral Spontaneous Extracranial Vertebral Artery Dissection

The most common mechanism of cerebellar infarction in young patients is arterial occlusion resulting from intracra-nial vertebral artery dissection. We describe a 26-year-old male patient with superior cerebellar artery infarction result-ing from a bilateral spontaneous extracranial vertebral artery dissection. The brain MRI showed an infarction of the left SCA territory and the angiography showed irregular stenosis with mural hematoma in the bilateral extracranial vertebral arteries. The angiography, taken 3 months later, showed recanalization of the arteries after serial treatments.

A Case of Primary Medullary Hemorrhage

We report a case of isolated primary medullary hemorrhage with a review of the literature to analyze the clinical presentation and radiological character. A 46-year-old man with chronic alcoholism developed tegmental medullary syndrome secondary to spontaneous hemorrhages in the medulla oblongata. Magnetic resonance imaging study was carried out on the third day after the second event, which showed two distinct isolated hematomas in the medulla oblongata. Digital subtraction angiography was normal. The cause of hemorrhage was presumed to be cryptic vascular malformation. The primary medullary hemorrhage usually presents with a characteristic syndrome of sudden onset vertigo with neurological signs that correspond to various combination of medial and lateral medullary involvement. Usually, the prognosis is good only with conservative treatment.