Faculty Bibliography

The blink reflex, the masseter reflex and the masseter inhibitory reflex ore sensitive tests to detect brain stem lesions and lesions of the peripheral facial and trigeminus nerve. The combined evaluation of the three brain stem reflexes seems particularly useful since all three reflexes ore mediated via different pathways. This allows further a more specific analysis of the structures or anatomical localisations involved in a specific dysfunction. They ore especially useful for follow-up examinations. $$:

The differentiation of occlusion versus pseudoocclusion of the internal carotid artery (ACI) has important impact on therapeutical considerations. Until now angiography is thought to be the 'gold standard' in the differential-diagnosis of occlusion and pseudoocclusion. However, colour doppler imaging and power doppler imaging ore the methods of choice for non-invasive diagnosis of extracroniell ACI-occlusion. The additional use of echo-contrast agents (e.g. Levovist(R)) improves the sensitivity of colour doppler imaging and the specificity of power doppler imaging. The combined use of various ultrasound techniques is highly sensitiv and specific for the differentiation of ACI-occlusian from pseudoocclusion and allows often for avoiding invasive techniques as angiography. Sensitivity and specificity of sonography ore dependent on the experience of the examiner. Besides the use of adequate diagnostic techniques it is important that the examination is done by a sonographist, who has wide experience in the field of carotid artery ultrasonography. $$:

Somatosensible evoked potentials (SEP) following stimulation of the trigeminal nerve provide additional diagnostic information in brainstem lesions. After stimulation of the upper and lower lip (separately or simultaneously) the afferent impulses reach the Nd. sensorius principalis nervi trigemini in the pens via the Gasseri ganglion. From there the impulses ore transmitted by the lemniscus trigeminalis to the thalamus and terminate in the postcentral gyrus (area 3b). The latency of the P19-peak is the most important parameter. Separate stimulation of the upper and lower lip allows for detection of even discrete lesions in the trigerminal system. By combining trigeminal SEP with other techniques such as auditory evoked potentials or blink reflex the exact localisation of brainstem lesions may be identified. Trigeminal SEP show in 41-100% of multiple sclerosis patients additional, clinically inapparent, foci. Also in ischemic brainstem lesions trigeminal SEP may provide additional information. In trigeminal neuralgia as well as in neurinoma of the acoustical nerve affection of the brainstem may be recognised by trigeminal SEP. $$:

Functional transcranial Doppler sonography (fTCD) examines cerebral hemodynamics at rest and during diverse activation manoeuvres. In the fTCD during visual activation the posterior cerebral artery (PCA) is insonoted. Further fTCD methods for the evaluation of the posterior circulation are the simultaneous insonation of the middle cerebral artery (MCA) and the PCA or direct insonation of the basilar artery (BA) during vestibular stimulation using caloric irrigation. The fTCD during tilt-table-test with heed-up tilt is meanwhile a very established method for autonomic testing. The fTCD during head-down tilt is still experimental for testing cerebrovascular autoregulation in healthy volunteers. The autoregulative stimulus is the rapid cephal blood influx which probably activates the myogenic mechanism of cerebrovascular autoregulation. The fTCD during ergometry examines cerebrovascular changes during physical stress. The cerebrovascular changes reflect the complex coactivation of diverse autoregulative mechanisms (neurogenic, metabolic, myogenic). In patients with defined cerebrovascular disturbances (chronic tension type headache, migraine) abnormal findings were detected. FTCD is a new method which enables noninvasive and with exact time correlation changes analysis of cerebrovascular hemodynamics during diverse activation procedures. Clinical applications can be seen in patients with cerebrovascular or autonomic diseases and in testing of cerebrovoscular autoregulation following pharmocological treatment (e.g. antihypertensive drugs). $$:

Spontaneous electrodermal activity can be derived from the palmar and plantar skin. These areas have a high density of sweet glands. Changes in potential at The sweat glands are considered to be the main cause for the measured electrodermal activity. A sympathetic skin response con be elicited by various arousal stimuli such as electrical, acoustic or emotional stimulation. SSR is used to diagnose autonomic sudomotor disorders of the peripheral and to some extent the central sympathetic nervous system. We describe the mechanisms of SSR generation, the technique of SSR recording and aspects of clinical application. $$:

The baroreflex is of major importance for the moment-to-moment maintenance of arterial pressure particularly during orthostatic stress. Blood pressure increase stimulates the receptors e.g. in the carotid sinuses and the aortic arch, and rapidly increases the receptor discharge rate. Blood pressure decrease induces arrest of impulse transmission to the nucleus of the solitary tract. The impulses are modulated by the nucleus ambiguous, the rostral ventrolateral medulla, the dorsal nucleus of the vagus nerve, parabrachial and paraventricular nuclei and other central structures. Blood pressure increase induces an increase of cardiovagal activity resulting in cardiodeceleration and a decrease of sympathetic peripheral vasoconstrictor outflow. The receptor firing rates show adaptation and resetting to longer lasting blood pressure changes, hysteresis, i.e. firing rates that are higher with rapid blood pressure increase than during the return to baseline pressure. The receptors interact with respiration, chemoreceptor stimulation, central stimuli, exercise and sleep, etc. Baroreceptor function and interaction e.g. with chemoreceptors is compromised in diseases such as diabetic autonomic neuropathy. Guillain-Barre syndrome, arterial hypertension, heart failure and probably in most stroke patients. Fatal complications may result from baroreceptor malfunction. Subtle analysis of the baroreflex is therefore crucial for a refined pathophysiological understanding of these diseases. Pharmacological testing and 'neck chamber' negative pressure stimulation of the receptors are as useful as the non-invasive computerized analysis of the interaction of spontaneous blood pressure and heart rate fluctuations

In Germany, 4-6 million men suffer from erectile dysfunction. Psychogenic, vascular, endocrine and metabolic disorders such as diabetes mellitus and neurogenic disturbances contribute to the etiology of erectile dysfunction. Erection depends on parasympathetic and - especially during emotional stimulation - on sympathetic outflow. The flaccid state is mediated via epinephrine and cotransmitters such as neuropeptide Y. Non-cholinergic, non-adrenergic neurotransmitters such as vasoactive intestinal polypeptide (VIP) and nitric oxide (NO) are essential for the erection. NO, VIP, calcitonin gene related peptide (CGRP) and prostaglandin El activate guanylate and adenylate cyclases and thus elevate levels of cyclic guanosine and adenosine monophosphate. A secondary decrease of calcium levels induces relaxation of smooth muscles of vessel walls and corpus cavernosum trabeculae and leads to erection. Specific phosphodiesterases cleave the cyclic monophosphates and terminate smooth muscle relaxation and erection. Diagnosis of erectile dysfunction is based on an extended history, interdisciplinary clinical examination, assessment of standard laboratory parameters, testosterone and prolactin levels and penile artery Doppler sonography. Cavernosometry, cavernosography, angiography and neurophysiologic procedures such as sphincter ani externus electromyography or bulbocavernosus reflex latency measurements are of limited diagnostic value. Psychotherapy, use of vacuum devices, vascular surgery and - as an ultimate option - penile prostheses are among the therapeutic alternatives. Today, intracavernosal or intraurethral application of vasoactive substances such as prostaglandin El and oral phosphodiesterase inhibitors such as Sildenafil are the most important therapeutic approaches. In the majority of patients, erectile dysfunction is most likely not primarily a psychological disturbance. Particularly diabetic patients benefit from adequate diagnosis and consequent therapy. Their therapeutic compliance is likely to improve with adequate therapy of erectile dysfunction. This might promote the prevention of secondary complications of the underlying metabolic disease. $$:

Entrapment syndromes ore due to chronic pressure induced lesions of peripheral nerves within an anatomical compartment of fixed size. Apart from the anatomical predisposition in a compartment, edema of surrounding tissue, endocrine, metabolic and traumatic factors, amyloid or mucopolysaccharid deposition contribute to the pathogenesis of entrapment syndromes. Hypesthesia, anesthesia, hypalgesia or hyperalgesia, paresthesia and dysesthesia in the skin areas supplied by the entrapped nerve, as well as motor weakness of muscles innervated by the nerve ore among the typical symptoms of on entrapment syndrome. Muscle atrophy can be seen in advanced stages. A detailed history, neurological and neurophysiolocial examination confirm the diagnosis. The carpal tunnel syndrome is the most frequent entrapment syndrome of the upper extremities. Entrapment of the ulnar nerve occurs in the ulnar groove at the elbow or at the cubital tunnel where the nerve posses The aponeurosis of origin of the flexor carpi ulnaris muscle. A more distal site of ulnar nerve entrapment is the Loge de Guyon. The various forms of thoracic outlet syndrome also induce tingling in the ulnar region of the hand. The anterior interosseus nerve syndrome and the pronator teres syndrome as well as the posterior interosseus nerve syndrome count among the less frequent entrapment syndromes. Therapeutical approaches depend on the anatomical structures, the pathogenesis and the severity of on entrapment. Conservative treatment is frequently sufficient to improve symptoms. Chronic and more advanced stages usually require surgery. $$: