The influence of the position of surface recording electrodes on the relative uptake of the masseteric and temporal M-responses in man

The present report aimed at evaluating the influence of recording conditions on the relative uptake of direct motor responses obtained in the masseter and temporalis muscles after electrical stimulation of their nerves, using a monopolar needle technique. In 10 subjects, various surface electromyographic recording set-ups were compared using supramaximal M-responses. Volume-conducted potentials originating from the masseter muscle could be recorded from the neck. For the masseter muscle, the optimal position for the active recording electrode was over the anterior and inferior part of the muscle belly. The configuration of the masseter M-response recorded from various positions over the muscle belly was highly variable both intra- and interindividually. The configuration of the M-response of the anterior part of the temporalis muscle showed less variability.

The influence of stimulating techniques on the masseteric and temporal M-responses in man

The direct motor responses obtained in the masseter and temporalis muscles after electrical stimulation of their nerves were evaluated. In 10 individuals, earlier stimulation techniques used to evoke M-responses ('bipolar needle' and 'surface' techniques) were compared with a previously undescribed 'monopolar needle' technique. The monopolar needle technique proved to give more stable stimulating conditions than the earlier techniques. Selective stimulation of the masseteric nerve or simultaneous stimulation of the masseteric and deep temporal nerves were found, depending on the position of the stimulating electrode.

Migrant sensory neuritis associated with AIDS: case report

We studied an AIDS patient who suffered from numbness, paresthesias and pain in the territories of different non-contiguous cutaneous nerves at different times. A transitory partial loss of touch and pinprick sensibility was also present in the same cutaneous areas. Sensory conduction velocities and SAP amplitudes were normal. The clinical picture was consistent with the Migrant Sensory Neuritis of Wartenberg. This rare neuropathy has never previously been described in patients affected by AIDS.

[Temporal muscle fatigue studied via muscle conduction velocity technics and spectral analysis of the electromyographic signal]

We examined 6 normal volunteers (3 males and 3 females, age 26-30). They were requested to clench as hard as they could until they felt pain. The experiment was repeated one hour later. Emg was recorded during the fatiguing exercise and the recovery period. We couldn't determine the muscle conduction velocity, probably because of the anatomy of the temporal muscle. The mean of the power spectrum showed wide variability and proved unsuitable for clinical applications, both for diagnosis and follow-up.

Unusual synkinetic movements between facial muscles and respiration in hemifacial spasm

We describe two cases of hemifacial spasm (HFS) with unusual synkinetic movements between facial muscles and respiratory activity. Patient 1 developed an idiopathic HFS. She underwent microvascular decompression surgery, followed by transitory facial nerve palsy; she recovered but later developed a facial synkinesia characterized by involuntary and forced eyelid closure on spontaneous and deep breathing; the orbicularis oculi muscle was active also when her mouth was open (the so-called Marin-Amat syndrome). Patient 2, 1 year after a peripheral facial nerve palsy (Bell's palsy), developed an HFS together with synkinetic movements between the orbicularis oculi muscle and respiration. In both cases electrophysiological studies showed pathological synkinetic electromyographic activity. An enhanced hyperexcitability of brain stem interneurons and facial motoneurons could be suggested to explain the phenomenon.

On the cause of tendon areflexia in the Holmes-Adie syndrome

A case of Holmes-Adie syndrome was studied clinically and electrophysiologically. A total loss of tendon reflexes was observed in upper and lower limbs. The main electrophysiological finding was a marked increase of the central conduction time after stimulation of peroneal and tibial nerves. Motor evoked potentials in soleus muscle after transcranial magnetic stimulation showed normal threshold and latencies. We suggest that tendon areflexia could be a consequence of a dysfunction of somatosensory large diameter afferent fibres at the spinal level.

Acute sensory and autonomic neuropathy: possible association with coxsackie B virus infection

This report describes a 26 year old woman with a Coxsackie B virus infection complicated by an acute pandysautonomic and sensory neuropathy. Electrophysiological studies suggested an axonal neuropathy. A sural nerve biopsy performed early in the disease showed axonal degeneration with a virtual absence of unmyelinated fibres and moderate loss of myelinated fibres, mainly affecting the small fibres; this differs from previous reports. An immune-mediated or direct virus action might explain the pathogenesis of this unusual evolution of a viral infection.

Magnetic motor evoked potentials (MEPs) in masseter muscles

Electromyographic responses of the masseter muscles and orbicularis oris muscles following transcranial magnetic stimulations were recorded with surface and needle electrodes. MEPs in masseter muscles (latency 6.9 +/- 0.71 ms, mean +/- SD) due to activation of controlateral cortico-nuclear connections were evoked by magnetic stimulations at 4 cm laterally to the vertex on the biauricular line. These MEPs were followed bilaterally by a silent period lasting about 20 ms and, less constantly, by a later silent period lasting up to 80 ms. The ipsilateral responses to the same stimuli presented shorter latencies and higher amplitudes and they were ascribed to direct stimulation of the trigeminal nerve, probably its intracisternal portion. Ipsilateral masseter "cortical" MEPs could be elicited only by a lower output setting (70% of the maximum output) of the stimulator. Orbicularis oris MEPs were polyphasic and dispersed with latencies ranging from 7 to 11 ms. In patients with hemispheric or capsular ischemic lesions "cortical" MEPs were absent when stimulating the affected hemisphere and present when stimulating the unaffected one. We suggest that the direct corticomotoneuronal projections for the masseter are mainly crossed.

[Dysgeusia in clinical practice. 2. Pathology]

The various types of dysgeusia are discussed and a clinical classification is proposed. Dysgeusia are divided according to the modifications of the intensity of the perception: ipergeusia and ipogeusie/ageusia. The latter are the most frequent and important ones; they are divided in congenital ones, rapidly developing ones, and slow developing ones. A practical way to distinguish among the rapidly arousing ones is to consider the duration of the symptom. If it lasts more than a week the probabilities of an underlying serious illness grow, mainly of CNS. The slow onset ones are most commonly due to general metabolic alterations, among which diabetes, and to common habits, like smoking.

[Functional velopalatal insufficiency. Therapeutic possibilities]

The function of the soft palate is complex; it takes part in speech, swallowing, and masticatory mechanisms. Its pathology ranges from morphological deficits to functional ones; these are commonly due to a central nervous system damage. The clinical analysis is based upon examination and instrumental prove, and leads to an optimum choice between surgical and prosthetic solutions. The latter is the best one in terms of quick execution, low costs and future possibilities of improvement.

[Dysgeusia in clinical practice. 1. Physiology]

The anatomical basis of taste are discussed both in their peripheral and in central aspects. The perception is based upon four principal flavors; this happens by complex chemical interactions between peripheral receptors of papillae and the taste producing substances. The nervous stimulus flows through fibres of VII-IX-X cranial nerves up to the tractus solitarius nucleus; successive elaboration leads to the taste sensation, whose principal cortical site is the zone between Silvius and Rolando's sulcus. The distribution of the sensible zones for the fundamental flavors is presented.

[Individual cast posts for single anterior implants]

The Authors utilized in order to replace anterior missing teeth osseointegrated implants provided with individual angled posts. These types of abutment are used to allow a good parallel situation between implants with different angulation and also between implants and proximal teeth. The head of this abutment is thread to receive the screw that allows the crown to be fastened.

[Handicapped situations in dentistry]

Moving from the general definition of "handicap" "the Authors suggest a classification system based upon the most important altered function of a patient. A handicap situation happens when a patient needs special care in a dental office, both for particular oral changes due to his primary pathology or related therapy and for increased operatory risks.

[Headaches and craniofacial pains with dental involvement in the classification of the International Headache Society (1988)]

Facial pain often presents complex diagnosis, requiring other specialists' consultation. The use of different terminology and protocols can affect the information exchange negatively. These problems in the field of headache, cranial neuralgias and facial pain lead the International Headache Society to introduce a new classification in 1988. The chief difference with the previous ones is the presence of strictly codified diagnostic principles. Its target is research, but it can help the general practice as well. We discuss the most interesting points to the stomatologist.

[Magnetic stimulation of the scalp: the responses of the masseter muscles. I]

Magnetic stimulation of nervous elements is a new neurophysiological technique. It easily succeeds in stimulating the brain motor cortex. We applied this technique to the trigeminal motor system, recording responses in masseter muscles. The magnetic stimulations at 4 cm laterally to the vertex on the biauricular line elicited responses in the contralateral masseter due to activation of motor cortex or adjacent elements along the cortico-nuclear pathway. The ipsilateral responses to the same stimuli and to more lateral ones presented shorter latencies and they were ascribed to direct stimulation of the trigeminal nerve, probably its intracisternal portion. The latency values were 6.9 +/- 0.71 ms and 3.6 +/- 0.3 ms respectively.

[Magnetic stimulation of the scalp: the responses of the masseter muscles. II]

Magnetic stimulation of nervous elements is a new technique of investigation in intact alert man. Electromyographic responses of the masseter muscles were recorded in normal volunteers and in two patients with hemispheric or capsular lesions, both by surface and needle electrodes. In the patients "cortical" responses were absent when stimulating the affected hemisphere and present when stimulating the unaffected one. These findings suggest that the direct facilitating cortico-nuclear projections for the masseter muscle are mainly crossed. Nevertheless the presence of clear ipsilateral responses after stimulation of the unaffected hemisphere demonstrates the existence of uncrossed projections; in fact only the ipsilateral motor cortex can be the site of origin of the responses in these patients.

[Masseteric responses following electrical stimulation of the scalp]

Electromyographic responses of the masseter muscles following electric transcranial stimulations by a conventional constant current stimulator were recorded with surface and needle electrodes. Ipsilateral motor evoked responses following both anodic and cathodic bipolar electrical stimulations performed at 7 and 11 cm laterally to the vertex on the biauricular line were recorded, with latencies ranging from 2 to 3.6 ms. Contralateral responses were not elicited. The ipsilateral responses to stimuli were ascribed to direct stimulation of the trigeminal nerve, probably its intracisternal portion.

Motor-evoked potentials in masseter muscle by electrical and magnetic stimulation in intact alert man

The electromyographic responses of the masseter after different types of transcranial stimulation were recorded with surface and needle electrodes. Magnetic stimulation at 4 cm lateral to the vertex on the biauricular line elicited MEPs in the contralateral masseter (latency 6.9 ms) due to activation of motor cortex or adjacent elements along the cortico-nuclear pathway. The ipsilateral responses to the same stimuli and to more lateral ones had shorter latencies and were ascribed to direct stimulation of the trigeminal nerve, probably its intracisternal portion. This was also the probable origin of the ipsilateral MEPs after both anodic and cathodic bipolar electrical stimulation at 7 and 11 cm lateral to the vertex on the biauricular line.