Transcranial Doppler ultrasonography (TCD) is a non-invasive method to evaluate cerebral hemodynamic changes in circle of Willis with Doppler principle. Two technical points that enable TCD are adoption of low frequency (2 MHz) ultrasound to penetrate bony window, and application of pulsed-wave Doppler mode allowing determination of the depth and sample volume of the insonated vessels. A standard examination technique should be applied through temporal, orbital, and suboccipital window (submandibular, if necessary) as in protocol. To shorten the time of examination, maximum power and large sample volume are recommended. It is crucial to perform a complete and through examination, although the examiner should target clinically involved arterial segment or suspected level of occlusion. Once the highest signal is found, avoid losing signal during switching the depth of insonation. Interpretation of Doppler waveform and pulsatility is important even more than flow velocity change alone. These parameters should be interpreted comprehensively with clinical information and other physiologic factors influencing TCD results.

It is important to understand proper transducer positioning, anatomic landmarks, and appropriate scale settings. A standard TCD examination technique through temporal, orbital, suboccipital, and submandibular window is proposed in this review article. To shorten the time of examination, maximum power and large sample volume are recommended. It is crucial to perform a complete and through examination, although the examiner should target clinically involved arterial segment or suspected level of occlusion. Once the highest signal is found, avoid losing signal during switching the depth of insonation. Recent studies have reported diagnostic and prognostic value of TCD waveform in acute stroke. Thrombolysis In Brain Infarction(TIBI) flow grade classifies waveform as absent, minimal, blunted, dampened, stenotic, and normal. TIBI represents the residual blood flow, and is well correlated with recanalization and early stroke outcome. Definition of each flow grade is introduced in this article. Recently developed new TCD machine adopts power motion mode(M-mode) Doppler, which provides a vascular ?oad map?through the acoustic window. It came to be easier to perform the TCD examination. In the future, more compact and easier-to-use machine will be developed, and TCD is expected to be a true ?erebral stethoscope?

Acute pandysautonomic neuropathy(APN) is an uncommon clinical entity involvement vasomotor, sudomotor, pupilomotor, secretomotor and other autonomic systems. Both sympathetic or parasympathetic fibers are involved with relative preservation of somatic sensory and motor function. Although APN shares several clinical features with GBS, it is not clear whether APN is a subvariety of GBS. We reported two young patients with APN. Patient I1 was a 18-year-old girl with recurrent fainting spells. Patients 2 was a 23-year-old man suffering from unexplained nausea and vomiting. Both had a history of previous upper respiratory infection. They presented with gastroparesis, anhydrosis and orthstatic hypotension. Mild numbness and tingling sense was present, but motor power was infact. Neurologic examination showed bilateral tonic pupil, decreased pain and vibration sense, and absent tendon reflexes. Nerve conduction study indicated diffuse sensorymotor polyneuropathy. Nerve biopsy in patient 2 revealed axonal degeneration. After conservative management, gastrointestinal symptoms were improved in patient 2, however, dysautonomic symptoms in young patient may indicate the diagnosis of APN. Although the natural course is generally benign, accurate diagnosis and proper management may be mandatory for the better clinical outcome.

Purpose
: Carpal tunnel syndrome(CTS) is a disorder of median nerve at wrist. it is usually diagnosed through clinical manifestation and nerve conduction study(NCS). However, sometimes, NCS does not provide a reliable evidence to reach the diagnosis. Thus, authors performed this study to determine whether NCS was correlated with specific parameters measured on magnetic resonance imaging (MRI) which might become a potential complemental diagnostic tool. Methods : We performed MRI in 34 wrists of 18 patients with clinical manifestations of CTS and pathologic nerve conduction values and analyzed them at levels of the distal radioulnar joint, pisiform and hook of hamate. Results : Increase in the cross-sectional area of the median nerve a the pisiform level and flattening, increased signal intensity, and contrast enhancement of the median nerve at levels of the pisiform and hook of hamate were statistically significant, Change in cross sectional areas between the distal radioulnar joint and hamate and the signal intensities at levels of pisiform and hamate were well correlated with the median nerve conduction velocity. Conclusions : Characteristic MRI findings in CTS reported previously were well demonstrated and some of MRI parameters are well correlated with nerve conduction study. MRI, despite cost, may help in evaluating CTS.

Transcranial Doppler ultrasonography (TCD) is a non-invasive and relatively cheap method of evaluating cerebral hemodynamics, allowing repeated measurements and continuous monitoring. Use of low frequency (2 MHz) ultrasound to penetrate bony window, and application of pulsed-wave Doppler mode allowing determination of the depth of the insonated vessels are two technical points. TCD measures velocity rather than flow, and therefore provides an estimation of cerebral blood flow only if vessel diameter remains unchanged. Mean flow velocity (MFV) and pulsatility index (PI) are the most commonly used parameters, which are influenced by various physiological variables and pathologic conditions. In clinical practice, detection of stenosis of the basal intracerebral arteries (>50-60%) is widely used, which is specific though not sensitive. Identification of occlusion or recanalization of vessels in acute stroke may provide useful information for thrombolytic therapy and prognosis. Monitoring of microembolic signal (MES) is a challenging field to detect the high-risk patients in asymptomatic carotid stenosis, and to evaluate the efficacy of anti-thrombotic therapy. CO2 or acetazolamide reactivity test is a useful method to detect significantly impaired hemodynamic reserve in patients with carotid occlusion, in which surgical revascularization may be beneficial. Newly developed echo-contrast agents and power Doppler instrument, which are expected to overcome the current technical limitation, and further progress of the transcranial color-duplex sonography also light up the future of neurosonology