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Biomedical subjects

C W Hess

Publications and source records attributed to C W Hess.

At least 91 records · Page 5Linked to original sources
PubMed1991

Isolated muscle hypertrophy as a sign of radicular or peripheral nerve injury.

Two patients with isolated neurogenic hypertrophy of the trapezius muscle due to accessory nerve injury and a patient with neurogenic hypertrophy of the anterior tibial muscle due to chronic radicular lesion L4 are described. Electromyography of the affected muscles showed dense continuing spontaneous discharges of complex potentials. Muscle biopsy performed in two patients showed abundant hypertrophic muscle fibres, identified in one case by ATP-ase reaction as being of predominantly type I. In the majority of previously reported patients with neurogenic muscle hypertrophy confined to the calf muscle, a passive stretch mechanism was suggested as a cause of the hypertrophy. It is assumed that the excessive spontaneous muscle activity gave rise to the hypertrophy in these patients. This may also be true in previously reported patients with neurogenic hypertrophy and similar spontaneous activity in electromyography.

Adult↗
PubMed1991

Central motor conduction in a family with hereditary motor and sensory neuropathy with pyramidal signs (HMSN V).

Two generations of a family affected by hereditary motor and sensory neuropathy with pyramidal signs (HMSN V) were clinically and electrophysiologically examined. Apart from electroneurographic studies, the central motor conduction (CMC) to arm and leg muscles was assessed using magnetic transcranial motor cortex stimulation. Abnormal CMC was confined to the clinically affected members, with the exception of an unaffected subject who had a diminished but normal latency response in a leg. The typical pattern was a significant diminution of the compound muscle action potential from the tibialis anterior and a moderately prolonged cortico-muscular conduction time (CoMCT) to this muscle.

Adult↗
PubMed1991

Influence of peripheral nerve stimulation on the responses in small hand muscles to transcranial magnetic cortex stimulation.

The influence of afferent median nerve stimulation on the responses of small hand muscles (CMAPs) to cortical stimulation (CortStim) was investigated by applying short stimulus trains to the median nerve at the wrist and slightly suprathreshold magnetic stimuli to the scalp. Train stimulus frequency (TSF), train stimulus intensity (TSI), and train onset (TO) in relation to the CortStim were varied. Amplitudes and latencies of CMAPs were compared with those obtained by CortStim alone. When applying short trains of 10 msec duration, of 300/sec-400/sec TSF, and of threshold or supramaximal intensity for motor fibers, both facilitatory and inhibitory effects on the responses to CortStim were achieved depending on the timing of the train onset. With a TO of 8-10 msec before CortStim, mean amplitudes of CMAPs were enhanced 3-10 times; mean amplitudes reached up to 20 times the baseline values when the TO was greater than 45 msec before CortStim. With a TO of 15-35 msec before CortStim, amplitudes were diminished below control values. No systematic changes in latency were noted with TO of 8-10 msec, but when the TO was 45-60 msec before CortStim the latencies of CMAPs were 1.5-3 msec shorter than baseline latencies. With afferent stimuli that were subthreshold for motor fibers facilitation only occurred when the TO was about 45 msec before CortStim. The differences were statistically significant (Wilcoxon-Mann-Whitney Test). This biphasic pattern of facilitation and inhibition probably reflects spinal and supraspinal reflex phenomena mediated by spindle receptor and various cutaneous afferents.

Action Potentials↗
PubMed1991

Transcranial magnetic stimulation of the facial nerve: where is the actual excitation site?

The site where excitation on the facial nerve to transcranial magnetic stimulation occurs was studied by recording the muscle responses of 13 patients who had facial nerve lesions at different locations, and by comparing the latencies of muscle responses to transcranial magnetic and direct electrical stimulation of the facial nerve recorded in another 5 patients undergoing posterior fossa surgery. The results of both approaches of this study led independently to the conclusion that magnetic stimulation acts within the proximal part of the facial canal. It is suggested that the cerebrospinal fluid (CSF) conducts the magnetically induced stimulation currents into the labyrinthine segment of the facial canal, where the facial nerve is still surrounded by CSF for about 10 mm.

Action Potentials↗
PubMed1991

Transcutaneous magnetic and electrical stimulation over the cervical spine: excitation of plexus roots-rather than spinal roots.

Percutaneous magnetic stimulation (MagStim) and electrical stimulation (ElStim) over the cervical spine were performed in 65 subjects. Compound muscle action potentials (CMAPs) from the abductor digiti minimi (ADM) and the biceps muscles (BICEPS) could be recorded in all subjects tested with both, ElStim and MagStim. Maximal stimulation as determined from the amplitudes of CMAPs was possible in most cases with ElStim but not with MagStim. Latencies after MagStim (centered over C7) and ElStim (cathode over C7/T1, anode positioned 6 cm cephalad in the midline) were not statistically significantly different (P = 0.3). However, in the individual case, it was difficult to predict the precise site at which the motor roots would be activated, since latencies of CMAPs to ElStim and MagStim could differ by up to 1.2 msec. In addition, the excitation site migrated distally when the stimulation intensity was increased with the aim to obtain CMAPs of nearly maximal amplitudes. The results of studying brachial plexus stimulation as well in 22 of the subjects led us to the conclusion that excitation of the motor roots occurs on the average 7 cm (range: 1.4-8.2 cm) proximally to Erb's point. This was confirmed by the finding that when the C7 motor root was stimulated directly intraoperatively within the intervertebral foramen, the excitation site was calculated to be 7.7 cm distal to the foramen and 8.4 cm proximal to Erb's point.

Action Potentials↗
PubMed1990

[Peroneal muscle atrophy with talipes cavus. Pyramidal symptoms and sensory disorders in one family. On the problem of the nosological classification of hereditary spinal diseases and polyneuropathies].

We describe a family with peroneal muscular weakness and atrophy with associated pyramidal signs. Onset of obvious symptoms was usually after the age of 50 years, but history pointed to subtle symptoms at an earlier age. The disorder was of autosomal dominant inheritance. The muscle weakness involved only the legs. All affected persons remained independent as regards their ability to walk. Sensory disturbances were never significant for the affected individual. With regard to the neurographies, the disease could be classified as a form of hereditary motor and sensory neuropathy (HMSN). The clinical picture, however, allows the classification of the disease as a form of spinal muscular atrophy or spastic spinal paralysis. We discuss the diagnostic implications of such disorders, which involve both the peripheral and the central motor pathways.

Adult↗
PubMed1990

[Bladder disorders in young adults with myelomeningocele: results of urodynamic-electromyographic studies].

Voiding disorders are common in patients with myelomeningocele (MMC) and are of great prognostic importance. We performed urodynamic-electromyographic measurements in 11 adolescent MMC patients who had undergone immediate postnatal surgery. None of our patients was able to urinate normally, and 9 suffered from some form of incontinence. The detrusor vesicae was hyper-reflexive in 6 patients and hypo-reflexive in 4. The bladder neck was never obstructive, but the striated sphincter was obstructive in 4. In 2 of these detrusor sphincter dyssynergy was found, and in 2 patients a non-relaxing sphincter was present. There was no correlation between the localization of the MMC and the type of dysfunction. The aim of any treatment of these disorders should be to prevent the development of vesico-ureteral reflux. Appropriate treatment requires the type of bladder dysfunction to be precisely known. Hence a urodynamic-electromyographic assessment should be performed in all MMC patients with voiding problems.

Adolescent↗
PubMed1990

Magnetic and electrical stimulation of cervical motor roots: technique, site and mechanisms of excitation.

Cervical motor roots and the brachial plexus were excited transcutaneously with magnetic (MagStim) and electrical stimulation (ElStim) applied dorsally over the spine and over the supraclavicular fossa (Erb's point). The compound muscle action potentials (CMAPs) from the abductor digiti minimi (ADM) and the biceps muscles (BICEPS) could be evoked with either stimulating technique in all 52 subjects tested. With MagStim over the spinous process C7, greater CMAPs were obtained from ADM (p less than or equal to 0.0001, paired t test) and BICEPS (p less than or equal to 0.005) when the inducing current in the coil as viewed from behind was clockwise for the right arm and vice versa. ElStim with the cathode over C7/T1 and the anode directed cranially provided greater CMAPs from the ADM (p less than or equal to 0.0001) and smaller CMAPs from the BICEPS (p less than or equal to 0.01) than with the inverse polarity. MagStim of the cervical roots provided CMAPs which were smaller from ADM (p less than or equal to 0.0001), and greater from BICEPS (p less than or equal to 0.0001), than ElStim (cathode C7/T1), whereas latencies did not differ significantly (p less than or equal to 0.3). When comparing ElStim and MagStim applied over Erb's point, the former yielded greater CMAPs and 0.5 ms longer latencies from both the ADM and BICEPS (p less than or equal to 0.001). From these data and additional studies in four patients, including direct intraoperative root stimulation in one of them, it is concluded that ElStim and MagStim over the spine excite the motor roots at a similar site, that is, within a few cm outside the intervertebral foramina. The site of stimulation is difficult to predict and depends on the placement of the stimulating devices and the intensities used. In contrast, MagStim of the brachial plexus over Erb's point occurs on average about 3.5 cm distal to the site of ElmStim.

Adult↗
PubMed1989

[Remission of a sleep apnea syndrome following aortocoronary bypass surgery].

It is well known that sleep apnea syndrome may develop or worsen in patients with cardiac failure. The case is reported of a patient with severe coronary artery disease involving three vessels but without symptoms or signs of cardiac failure. Aortocoronary bypass operation nevertheless eliminated the coexisting sleep apnea syndrome.

Aged↗
PubMed1989

[Non-epileptic impaired consciousness in neurologic diseases].

Transient recurrent confusional and stuporous states of nonepileptic origin are clearly less frequent than epileptic ones. They are relatively common in diseases of disturbed vigilance, like narcolepsy, idiopathic hypersomnolence, and sleep apnea. These patients often suffer from attacks of hypovigilance, characterized by altered awareness, automatic behaviour and partial or complete amnesia for the attack. Because of the memory 'black outs' and the frequently associated hypnagogic hallucinations, the patients behave inappropriately and often appear confused. Confusional states also typically arise during basilar artery migraine attacks. This special form of complicated migraine predominantly affects young females and is characterized by symptoms and signs of brain stem dysfunction such as vertigo, ataxia, paresthesia, limb weakness, dysarthria; in 75% of the cases, disorders of consciousness dominate. Transient ischemic attacks are sometimes recurrent and, when involving the cranial basilar territory, may result in confusional states without significant motor dysfunction. Attacks of transient global amnesia are possibly also ischemic in nature and are assumed to arise from transient bilateral limbic failure. Affecting only memory functions, they are strictly spoken not confusional, but must nevertheless be taken into consideration when proper observation during the attack was not possible.

Adult↗
PubMed1989

Significance of shape and size of the stimulating coil in magnetic stimulation of the human motor cortex.

Three different stimulating coil designs were evaluated for magnetic motor cortex stimulation by comparing threshold stimulus intensities at different sites over the scalp for exciting upper and lower limb muscles. Little difference was found between stimulation characteristics of two circular coils of different size, the smaller coil delivering slightly more focal stimuli. A twin coil composed of two single circular coils in series arranged side-by-side, produced significantly more powerful and more focal stimuli. It proved to be superior for exciting the leg muscles, in that less output energy was needed. For all coils, the orientation of the inducing current over the presumed motor area was the most critical stimulation parameter, and a sagittal current in anterior direction or coronal towards the stimulated hemisphere was optimal for the upper limb or lower limb muscles, respectively.

Adult↗
PubMed1989

The reliability of type-token ratios for the oral language of school age children.

This study investigated the alternate forms reliability of four type-token ratios (TTRs) of oral language samples obtained from 52 elementary school children (9 through 12 years of age). The four TTRs included the basic type-token ratio, the corrected type-token ratio, the root type-token ratio, and the bilogarithmic type-token ratio. Language samples of 600 words were segmented into 50-word, 100-word, and 200-word samples. Within each TTR measure, there were no significant differences among the means for samples of the same size, but all means for a given sample size differed significantly from the means of all other sample sizes. Further, for samples of the same size the reliability coefficients calculated for each TTR measure were neither consistent nor significant. These findings indicate that under the conditions of the present study TTRs are not comparable when calculated for different sample sizes ranging from 50 to 600 words, and further, that they are not reliable measures of the language performance of individual elementary school children from regular classrooms for language samples of 50 to 200 words.

Child↗
PubMed1989

Investigation of facial motor pathways by electrical and magnetic stimulation: sites and mechanisms of excitation.

A refined technique is described for non invasive examination of the facial motor pathways by stimulation of the extra- and intracranial segment of the facial nerve and the facial motor cortex. Surface recordings from the nasalis muscle rather than from the orbicularis oris muscle were used, since the compound muscle action potential (CMAP) from this muscle showed a more clearly defined onset. Electrical extracranial stimulation of the facial nerve at the stylomastoid fossa in 14 healthy subjects yielded a mean distal motor latency of 3.7 ms (SD 0.46), comparable with reported latencies to the orbicularis oris muscle. Using a magnetic stimulator, transcranial stimulation of the facial nerve was performed. The mechanism of transcranial magnetic facial nerve stimulation was studied using recordings on 12 patients who had facial nerve lesions at different locations, and with intraoperative direct measurements in four patients undergoing posterior fossa surgery. The actual site of stimulation could be localised to the proximal part of the facial canal, and a mean "transosseal conduction time" of 1.2 ms (SD 0.18) was calculated. The cerebrospinal fluid (CSF) played an important role in mediating the magnetically induced stimulating currents. Finally, with transcranial magnetic stimulation of the facial motor cortex, clearly discernible CMAPs could be produced when voluntary activation of several facial muscles was used to facilitate the responses. From this, a central motor conduction time of 5.1 ms was calculated (SD 0.60, 6 subjects).

Action Potentials↗
PubMed1989

[A method of electrical cervical motor root stimulation: effect of stimulation parameters and normal values].

Following percutaneous stimulation over the cervical column, a compound action potential (CMAP) can be recorded from the muscles of the arm. The actual site of excitation is located on the spinal motor roots, probably near to their exit from the spinal column. This method allows the electroneurographical assessment of the proximal brachial plexus and is used to calculate a central motor conduction time following motor cortex stimulation. So far, the optimal placement of the stimulating electrodes is unknown, and normal values must be established. We measured onset latencies of CMAPs of Mm biceps brachii and abductor digiti minimi (ADM) after supramaximal cervical motor root stimulation in 31 healthy subjects. Distances between the stimulating electrodes varying from 3 to 12 cm were studied. With 6 cm interelectrode distance, the electrodes were then placed either in a longitudinal or in a transversal direction, with the cathode over the interspace C7/T1 or C6/7. In addition, for the longitudinal stimulation, the effect of cathodal versus anodal stimulation over the C7/T1 interspace was studied. The results of various stimulating electrode positions and directions over the lower cervical column were then compared statistically. With the longitudinal electrode position, the cathode over C7/T1 and the anode placed 6 cm cranially, it was always possible to excite muscles from both sides simultaneously. When a very proximal stimulation site at the nerve roots was required in both muscles after one single stimulus, this method was superior to the transversal electrode position with the cathode C6/7 or C7/T1, or to the longitudinal electrode position with the anode over C7/T1 and the cathode placed cranially. For the ADM (29 subjects, 58 sides), the mean onset latency was 13.795 +/- 1.307 ms (mean +/- 1 SD), the mean side-to-side difference (SSD) was 0.452 +/- 0.388 ms. The mean amplitude was 7.71 +/- 2.64 mV, the mean side-to-side quotient (SDQ) was 41.88 +/- 97.59%. For M. biceps (29 subjects, 58 sides), the mean onset latency was 5.138 +/- 0.582 ms, the mean SSD 0.166 +/- 0.193 ms. The mean amplitude was 7.91 +/- 3.45 mV, the mean SSQ was 55.42 +/- 67.94%.

Adult↗
PubMed1989

[Transcranial magnetic stimulation of the motor cortex and percutaneous magnetic stimulation of the peripheral nervous structures in the dog].

The motor cortex was transcranially and peripheral nervous structures (motor roots, plexus, peripheral nerves) were percutaneously stimulated by magnetic pulses in awake dogs and in dogs awaking from general anesthesia. The compound muscle action potentials were recorded by surface or needle electrodes. The central motor conduction time as an information about central motor tracts was obtained by subtracting the peripheral latency from the corticomuscular latency. The peripheral latency was assessed by high voltage electrical and magnetic stimulation of motor roots and by the F-wave technique. The motor conduction velocity of the tibial nerve was measured by percutaneous magnetic and by electrical stimulation and the resulting values were compared.

Action Potentials↗
PubMed1988

[Therapy of brain-related minor seizures].

The pharmacotherapy of minor seizures depends on the type of epileptic manifestation. Generalized minor seizures (petit-mal) must be differentiated from focal (partial) seizures. The former are further divided into the typical absence attacks of childhood and benign myoclonic seizures. The drug of choice for both forms of generalized minor seizures is valproate, which also has the advantage of being reliably effective against the frequently associated grand-mal seizures. The focal seizures' epileptic activity is either in the neocortex (simple partial seizures) or in the limbic system (complex partial seizures). Neocortical focal seizures are characterized by motor jerks in one limb (Jacksonian type), head turning (adversive attack), or localized sensory manifestations, and limbic or psychomotor attacks by brief impairment of consciousness and often by motor automatisms. Focal seizures, which are sometimes difficult to control, are best treated with carbamazepine or phenytoin.

Anticonvulsants↗