Electrodiagnostic features of the Guillain-Barré syndrome: the relative sensitivity of different techniques.

We compared the diagnostic sensitivity of somatosensory evoked potentials (SEPs) and F waves with peripheral motor and sensory nerve conduction studies in 15 patients with the Guillain-Barré syndrome. All 4 types of studies were performed on 44 nerves (17 median, 12 ulnar, and 15 lower extremity). In the lower extremities, we used the peroneal nerves for all types of study except peripheral sensory conduction studies, which were performed on the sural nerve.

The role of thermography in the evaluation of lumbosacral radiculopathy.

We studied 27 normal subjects and 30 patients with low back pain to evaluate the diagnostic accuracy of thermography in the diagnosis of lumbosacral radiculopathy. Thermographic abnormality was defined as the presence of either interside temperature difference exceeding 3 standard deviations from the normal mean, or an abnormal heat pattern overlying the lumbosacral spine. In patients with clinically unequivocal radiculopathy, thermography and electrophysiologic study were similar in diagnostic sensitivity, and the 2 methods agreed on the presence or absence of abnormality in 71% of cases.

Effects of different sensory inputs on the median-derived somatosensory evoked potential.

We studied the effect of a variety of "interfering" stimuli on the median-derived somatosensory evoked potentials recorded over Erb's point, cervical spine, and scalp. We found that the amplitude of N20 and P27 recorded over the scalp was attenuated by active movement, vibration, and tactile stimulation of the ipsilateral hand but not by passive movement. Cervical and peripheral responses were unaffected.

Neurology: botulinum toxin therapy for torticollis.

The Scientific Board of the California Medical Association presents the following inventory of items of progress in neurology. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and important clinical significance. The items are presented in simple epitome and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item.

Red cell deformability and lipid composition in two forms of acanthocytosis: enrichment of acanthocytic populations by density gradient centrifugation.

Whole cell deformability and lipid determinations were performed on red cells from two patients who had acanthocytes in the peripheral blood (10% and 20% to 30%) and normal serum lipoprotein levels. One patient had typical chorea-acanthocytosis and the other had no clinical abnormalities associated with acanthocytosis. Red cells from the patient with chorea-acanthocytosis showed reduced deformability, as measured by a visco-diffractometric method (ektacytometry), which could be explained by the presence of increased numbers of dehydrated cells containing high concentrations of hemoglobin.

Evaluation of thermography in the diagnosis of selected entrapment neuropathies.

We studied 20 normal subjects, 22 patients with carpal tunnel syndrome, and 15 with ulnar neuropathy at the elbow to compare the diagnostic accuracy of infrared thermography with that of conventional electrodiagnostic studies. We found abnormal thermograms in 55% of patients with carpal tunnel syndrome and 47% with ulnar neuropathy, using 2.5 SD from the normal mean as criteria for abnormality.

Controlled trial of botulinum toxin injections in the treatment of spasmodic torticollis.

We administered local injections of botulinum toxin to 20 patients with torticollis in a blinded, placebo-controlled study. Each patient received four sets of injections: three different doses of botulinum toxin and one placebo. The order of the sessions was random and unknown to the patients.

The use of somatosensory evoked potentials in the evaluation of the central nervous system.

SEPs may be recorded over the spine and scalp to stimulation of any accessible mixed or sensory nerve in the extremities. SEP abnormalities are useful in detecting lesions in central somatosensory pathways. They do not establish a specific diagnosis, but they may suggest or support a diagnosis made on clinical grounds.

AAEE minimonograph #32: the electrophysiologic examination in patients with radiculopathies.

A brief history of the evolution of radiculopathy as a clinical entity, and the use of electrodiagnostic studies to diagnose it, are provided. Root anatomy and the concept of myotomes and dermatomes are reviewed, as is the pathophysiology of radiculopathy. The value and limitations of the various electrophysiologic procedures used in the diagnosis of radiculopathies are discussed, including motor and sensory nerve conduction studies, late responses, somatosensory evoked potentials, nerve root stimulation, and the needle electrode examination.

Neuromuscular effects distant from the site of botulinum neurotoxin injection.

We assessed the severity and temporal profile of distant neuromuscular effects from a single dose (280 units) of botulinum neurotoxin injected into neck muscles for torticollis. We performed single-fiber EMG studies on the biceps brachii of six patients to measure jitter (20 pairs) and fiber density on the initial treatment day and then again, at least once more, after 2 to 12 weeks. No patient developed weakness beyond the neck muscles or decrement of the biceps response to repetitive 3-Hz nerve stimulation.

Effect of reference point on visual evoked potentials: clinical relevance.

For clinical purposes the VEP is generally recorded from the mid-occipital region referenced to the vertex or mid-frontal region. This may lead to interpretive errors that can be avoided if a relatively inactive reference point, such as linked mastoids, is used simultaneously. The additional recording derivation may also be helpful in clarifying aberrant or ambiguous wave forms.

Electrocerebral accompaniments of syncope associated with malignant ventricular arrhythmias.

Study Objective: To examine the electrocerebral and clinical accompaniments of syncope associated with malignant ventricular cardiac arrhythmias.

Design: Survey of clinical and electroencephalographic changes during induced cardiac dysrhythmia.

Setting: Clinical electrophysiology laboratory of a university medical center.

Recovery of peripheral and central responses to median nerve stimulation.

We recorded the responses to paired stimuli delivered to the median nerve at the wrist in 8 healthy adult volunteers, in order to characterize the recovery of function after a single conditioning stimulus. Responses were recorded over the nerve at the ipsilateral elbow and in the Erb's point region, over the second cervical spinous process, and over the contralateral 'hand area' of the scalp. The data from 1 subject were discarded because of possible artifactual contamination.

Ambulatory EEG recordings in epileptic and nonepileptic children.

We examined the cassette-recorded 24-hour ambulatory EEG findings in children who had either clinically definite seizures or episodic behavioral disturbances not regarded as epileptic on clinical grounds. Among 40 epileptic patients, 22 had one or more attacks during the 24-hour recording session. In 15 of these patients all clinical attacks had appropriate ictal electrographic accompaniments; in another 6 some (but not all) attacks did so.

The clinical course of spasmodic torticollis.

Among 24 of 36 patients with idiopathic spasmodic torticollis referred to one of us over a 10-year period, who were followed up for more than 1 year, we defined three outcome groups. Three patients (13%) underwent complete or almost complete remission at a median of 3.0 years into the illness.

Relative utility of different electrophysiologic techniques in the evaluation of brachial plexopathies.

We report the results of detailed electrophysiologic studies in 23 patients with suspected brachial plexopathies. In five with neurogenic thoracic outlet syndrome, needle EMG and determination of size of ulnar sensory nerve action potentials (SNAPs) and thenar M waves were important in localizing the lesion; F-response and somatosensory evoked potential (SEP) studies were of more limited utility. All electrodiagnostic studies were normal in 10 patients with nonneurogenic thoracic outlet syndrome.

Unusual type of spinal arteriovenous malformation.

We describe an uncommon type of spinal arteriovenous malformation that is intradural rather than dural and that consists of a true fistula rather than a nidus of abnormal vessels between the anterior spinal artery and a draining vein. Its clinical significance and treatment are discussed.

Barbiturate anesthesia in the treatment of status epilepticus: clinical experience with 14 patients.

We report our experience using barbiturate anesthesia for the treatment of refractory status epilepticus. Following a retrospective review of eight patients treated with a variety of barbiturates and dosing regimens, we established a specific protocol employing pentobarbital and evaluated it prospectively in six patients. Among the 14 patients, intravenous barbiturates, when administered with a loading dose followed by continuous infusion, were uniformly effective in aborting seizures and producing a burst-suppression EEG pattern.

Visual evoked potentials in the investigation of "blindsight".

We recorded long-latency visual evoked potentials in four patients with homonymous hemianopias, one of whom had clinical evidence of "blindsight." Stimuli consisted of different words that appeared randomly and at a constant angle to either side of the center of a TV screen, and subjects responded to one previously specified word (the "target") by finger extension. Target stimuli in the intact hemifield elicited a well-formed P3 response in all subjects, whereas stimuli in the blind field produced no such response except in the subject with blindsight.

Sensory discrimination and its relationship to the cerebral processing of infrequent stimuli.

We recorded cerebral evoked potentials, back and forward averaged from the EMG onset of the responding muscle, in three reaction time tasks, each requiring an identical motor response to an identical stimulus but differing in the nature of the sensory discrimination required. Two types of stimuli were presented: a rare one to which the subject responded with finger-extension, and a frequent one to which no response was required. We found a close but variable relationship between the cerebral events associated with performance of a task and the timing of the motor response.

Parkinson's disease in the elderly: current management strategies.

Parkinson's disease generally responds well to dopaminergic therapy, but there is no unanimity concerning the optimal time for introducing dopaminergic medication. Dose-related side effects of these drugs may respond to a drug holiday, and fluctuations in response to levodopa may sometimes be helped by addition of bromocriptine to the drug regimen. Anticholinergic drugs, tricyclic compounds, and amantadine may sometimes lead to benefit, but any antiparkinsonian effect is often disappointing.