Visually Evoked Sympathetic Skin Response in Normal Subjects

BACKGROUND: Sympathetic skin response (SSR) is a transient change in the electrical potential of the skin that is evoked by internal or external stimuli. In the present study, our purpose was to compare electrical and visual stimulation methods of evoking a SSR. METHODS: SSRs evoked by both electrical and visual stimulation were recorded from the palm and sole from 48 healthy volunteers. RESULTS: SSRs were obtained in all normal control subjects following both electrical and visual stimulation. The latency of SSR following electrical stimulation was 1383.75+/-223.56 msec at the palm and 1790.54+/-318.70 msec at the sole, and that following visual stimulation was 1518.75+/-252.64 msec at the palm and 1930.10+/-226.19 msec at the sole. The latencies of SSRs following visual stimulation were prolonged significantly more than those following electrical stimulation. The amplitudes of SSRs following visual stimulation were significantly lower than those following electrical stimulation, and the amplitude of SSRs following both electrical and visual stimulation had marked intersubject and intrasubject variabilities in each of the stimulations. CONCLUSIONS: The SSR evoked by visual stimulation is as reliable as known electrical stimulation for determining sympathetic functions and is a less invasive method. Latencies by visual stimulation are longer than those by electrical stimulation in both the palm and sole. The visual stimulation method of evoking a SSR is not influenced by an ascending somatosensory pathway theoretically, so we can postulate that it reflects a purely autonomic function if there is no problem in the visual pathway.

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.