PubMed Health⌕ Search

Biomedical subjects

E Favale

Publications and source records attributed to E Favale.

At least 37 records · Page 2Linked to original sources
PubMed1991

Motor evoked potentials (MEPs) in lacunar syndromes.

Motor evoked potentials (MEPs) evoked in the biceps, thenar and tibialis anterior muscles by electrical stimulation of the scalp and of the spinal regions were recorded in 32 patients with focal deficits due to minor cerebral ischemia of the lacunar type and in a control group. Somatosensory evoked potentials (SEPs) to median nerve stimulation were also recorded. The central motor conduction times (CMCTs) and the threshold intensities for eliciting MEPs in the relaxed muscles were significantly increased on the affected side. Central motor conduction, for at least one muscle, was altered in 18 patients. MEP abnormalities were related to pyramidal signs (though they could be observed also in a patient without any motor impairment) and occurred independently of a specific clinical picture or a radiologically confirmed lacunar lesion. SEPs were less frequently altered than MEPs.

Aged↗
PubMed1991

Hemisphere asymmetry in decision making abilities. An experimental study in unilateral brain damage.

Thirty control subjects and 60 unilateral brain-damaged patients, 30 with left hemisphere (LH) damage and 30 with right hemisphere (RH) disease, underwent a disjunctive 4-choice reaction time study. Speed of reaction (as defined by the reciprocal of reaction time (RT), movement time (MT) and total response time (TRT] and accuracy of response (as represented by the sum of errors in selecting the correct response key) were investigated comparatively as a function of side of lesion and of performance on Raven's Coloured Progressive Matrices (PM47). In contrast to movement speed (1/MT), reaction speed (1/RT) as well as total response speed (1/TRT) showed a lesion effect independent of side of damage. Conversely, accuracy was differentially impaired, LH damage being associated with a significantly higher number of errors. Speed and accuracy had different relationships with the performance on the PM47 in the two hemisphere groups. Speed was affected in parallel with changes in PM47 performance both in the LH and in RH groups, whereas accuracy was altered only in LH patients. It was concluded that speed of motor reaction is affected by unilateral brain lesions irrespective of their side, whereas decision making processes, as expressed by accuracy of response, seem to be specifically impaired by LH damage.

Attention↗
PubMed1991

Changes in central delay of soleus H reflex after facilitatory or inhibitory conditioning in humans.

1. Central delay (CD) changes after facilitatory or inhibitory conditioning of the soleus H reflex have been investigated in a group of normal subjects as a function of the conditioning and test stimulus intensities and also as a function of the Hmax/Mmax ratio. Both facilitation and inhibition of the reflex response have been obtained by conditioning stimulation of the ipsilateral tibial nerve at suitable conditioning-test stimulus intervals. CD changes have been extrapolated from the variations of the time interval between afferent and efferent neural volleys underlying the H reflex, directly recorded from the sciatic nerve. 2. The CD was significantly decreased by facilitatory and increased by inhibitory conditioning. Facilitatory CD changes were positively related to test stimulus strength (at a given conditioning stimulus intensity) and negatively related to conditioning stimulus strength (at a given test stimulus intensity). Both trends were reversed after inhibitory conditioning. The effectiveness of facilitatory conditioning was positively related to the individual Hmax/Mmax ratio whereas a negative relationship could be observed after inhibitory conditioning. 3. Also, the "conditioning threshold" (the minimal conditioning stimulus strength affecting the reflex size) and the "maximal conditioning effect" (the conditioning stimulus intensities leading to either the saturation of the facilitatory effect or the suppression of the reflex response) were significantly related to the Hmax/Mmax ratio. 4. We suggest that temporal changes in the H reflex pathway after facilitatory or inhibitory conditioning stimuli depend both on the size of the motoneuronal pool underlying the reflex response, as determined by the test stimulus intensity, and on the individual excitability of the motoneuronal pool, as defined by the Hmax/Mmax ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Diagnostic relevance of trigeminal evoked potentials following infraorbital nerve stimulation.

A new tool in neurophysiological exploration of the trigeminal nerve has recently been introduced. It has been demonstrated that stimulation of the infraorbital nerve trunk gives rise to very reliable scalp responses reflecting the activity of the afferent pathway between the maximally nerve and the brain stem. The authors demonstrate that alterations of such trigeminal evoked responses fit with documented pathological processes at various locations along the trigeminal pathway (maxillary sinus, parasellar region, and within the brain-stem parenchyma). They report the findings in 68 patients suffering from "idiopathic" trigeminal neuralgia. Alterations of the response were detected in 33 cases, suggesting that some damage of the nerve had taken place either at the root entry zone into the pons (23 cases) or slightly distal to it (10 cases). Such results support the hypothesis that trigeminal neuralgia may be due to a compression of the trigeminal root at the pons entry zone.

Adult↗
PubMed1990

Impaired habituation of long-latency stretch reflexes of the wrist muscles in Huntington's disease.

Electromyographic responses to sudden wrist extension were recorded from the forearm and finger flexor muscles in 10 patients with Huntington's disease (HD) and in 10 normal controls. Stretch reflexes were characterized by a short-latency (SL) and a long-latency (LL) component both in patients and controls. Latency, duration, and size of the SL component were not different in the two groups, whereas the LL component was delayed in latency and reduced in size in HD patients. Increasing the stretch repetition rate from 0.1 to 0.4 cycles/s did not affect the SL component of either group, whereas the LL stretch reflex was reduced in size and duration in normal controls, but not in HD patients. These findings suggest an impairment of the "gain" mechanisms of the sole LL component, responsible for a desaturation of this component. This study supports the hypothesis that LL stretch reflexes are mediated by a transcortical long loop, possibly damaged in HD.

Adult↗
PubMed1990

Selective effects of repetition rate on frontal and parietal somatosensory evoked potentials (SEPs).

The effects of changing the stimulus presentation rate on early parietal (N20-P25) and frontal (P22-N30) somatosensory potentials (SEPs), evoked by median nerve stimulation, were investigated in 15 normal subjects. Stimuli were presented at 0.1, 0.4, 1.0, 4.0 and 10/sec. Only minor latency changes, mainly for the frontal P22 component, were observed when the stimulus rate was increased up to 10/sec: while the frontal P22-N30 complex was more rapidly and severely reduced in amplitude than the parietal N20-P25 complex. The differential effects of stimulus presentation rate on early frontal and parietal SEPs support the hypothesis of separate neural generators and suggest that the choice of the stimulation frequency may be critical for the interpretation of diagnostic SEP studies.

Adult↗
PubMed1990

Generalized dystonia with bilateral striatal computed-tomographic lucencies in a patient with human immunodeficiency virus infection.

We report the case of a 36-year-old, drug-addicted woman with laboratory evidence of human immunodeficiency virus infection in the central nervous system. The patient presented with generalized dystonia involving both axial and segmental muscles, mainly in the legs, and with minimal additional neurological abnormalities. A computed-tomographic scan revealed bilateral and symmetrical lucencies in the putaminal region. The possibility of an acquired immunodeficiency syndrome-related manifestation is discussed.

AIDS Dementia Complex↗
PubMed1990

Early scalp responses evoked by stimulation of the mental nerve in humans.

In 20 subjects, we stimulated the mental nerve through needle electrodes inserted into the homonymous foramen; recording electrodes were placed on the scalp and along the jaw. Within the 1st 5 msec after the stimulus we recorded 4 constant waves, thought to reflect the afferent activity from the mandibular nerve up to the trigeminal nuclei. These waves have similar characteristics and the same high degree of reliability as those obtained after stimulation of the infraorbital and supraorbital nerves; therefore, they should be a useful complement for a complete exploration of trigeminal nerve function.

Adult↗
PubMed1988

Do muscle afferents contribute to the cervical response evoked by electrical stimulation of the median nerve in man?

The possible contribution of low threshold muscle afferents to the postsynaptic component (N13) of the cervical response evoked by electrical stimulation of the median nerve (MN) was investigated in normal subjects. Electroneurographic (ENG) and electromyographic (EMG) correlates of the reflex motoneuronal discharge (RMND) were recorded simultaneously. A. No reflex activity could be elicited by stimulation of the MN at the wrist, at least in the resting subjects, while well developed ENG (P2 efferent volley) and EMG (H reflex) monosynaptic responses occurred following stimulation of the MN at the elbow at suitable strengths. In neither case could a surface correlate of interneuronal activity evoked by muscle afferents be demonstrated. B. Recruitment curves showed that at stimulus intensities above maximal for the H reflex both P2 and H responses started to decrease until they completely disappeared, while N13 showed further enhancement. C. Subthreshold conditioning stimulation of the MN enhanced both P2 and H responses, while vibratory muscle stimuli provoked a clearcut suppression of these two responses. In contrast, N13 was completely unaffected by either manoeuvre. D. No cervical evoked activity could be detected following tendon tapping of the anterior forearm muscles in spite of the appearance of well developed cortical responses and the ENG and EMG correlates of the T reflex. E. Conditioning volleys elicited by tendon taps of the anterior forearm muscles suppressed both P2 and H responses following stimulation of the MN at the elbow without affecting the related N13 component. Conditioning supramaximal stimulation of the MN at the wrist suppressed the N13 component of the cervical response evoked by stimulation of the MN at the elbow without affecting the related reflex responses. No component chronologically related to the RMND could be recorded at the posterior neck region during suppression of N13, thus ruling out the possibility that failure to detect the RMND (as well as its interneuronal concomitants) with cervical electrodes is due to a masking effect of the N13 component. G. Conditioning tendon taps of anterior forearm muscles provoked a clearcut reduction of the primary cortical response to finger stimulation without affecting the postsynaptic component of the related cervical response. It is concluded that neither segmental (motoneuronal or interneuronal in origin) nor ascending postsynaptic impulses generated in the spinal cord by stimulation of low threshold muscle afferents contribute to N13, the latter being probably due to activation of both short and long axoned spinal neurons by cutaneous afferents.

Adult↗
PubMed1988

Somatosensory evoked potentials in lacunar syndromes.

Parietal and prerolandic somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded from 40 patients with lacunar syndromes due to CT-verified lacunar infarcts. The control group consisted of 30 age-matched normal controls. Nineteen patients showed SEP abnormalities, mainly an increase of height-covariated latency of cortical components and/or of the central conduction time. Such changes occurred independently of the clinical features of lacunar syndromes, being related more to the lesion location than to its size. SEP studies may be a useful adjunct to the clinical diagnosis of lacunar infarct, possibly also when the CT scans are normal.

Adult↗
PubMed1988

Electrical stimulation of the motor tracts in cervical spondylosis.

Motor action potentials evoked by percutaneous electrical stimulation of the scalp and of the cervical (or lumbar) vertebral region were recorded from the biceps, thenar and tibialis anterior muscles in 30 patients with cervical spondylosis. Twelve normal controls were matched for age and height. Abnormalities of central motor conduction (absence or increased central delay of cortical responses) for at least one muscle were observed in all (but one) the patients with myelopathy alone or combined with radiculopathy. An increase in latency of the responses evoked by cervical stimulation occurred in 40% of patients with radiculopathy or myelo-radiculopathy. Changes of motor conduction occurred even in the absence of abnormalities of somatosensory evoked potentials, while the opposite was never observed. Direct stimulation of the motor tracts may be of value in the functional assessment of the motor pathways in cervical spondylosis.

Adult↗
PubMed1987

Electrophysiological analysis of motor control in patients with vascular hemichorea.

An EMG analysis of motor control was performed in 4 patients with unilateral choreic movements of sudden onset, 3 of whom presented CT scan evidence of lacunar infarcts involving the contralateral striatum. The choreic dyskinesias were correlated with EMG bursts of variable duration occurring with a random order of activation. Ballistic elbow flexion movements were performed with a normal triphasic EMG pattern, but both size and duration of the first agonist burst were increased on the affected side. Abnormalities of cerebral somatosensory evoked responses were observed in 3 patients on stimulation of the side with choreic movements.

Aged↗
PubMed1987

Subcortical and cortical responses following infraorbital nerve stimulation in man.

Scalp responses following stimulation of the infraorbital nerve have been recorded in awake and anaesthetized subjects from non-cephalic (NCR) and vertex (VR) reference derivations. In awake subjects, after 3 very early potentials (W1, W2 and W3), 4 small components (P4, N5, P6 and N7) with widespread distribution have been constantly recorded from NCR derivations. Sometimes a further component, named N10, could be recorded in VR derivations on the scalp contralateral to the stimulus in the absence of earlier events. Large and inconstant waves were recorded following N7 in NCR and N10 in VR derivations. The muscular origin of these waves was demonstrated by simultaneous records taken from scalp and muscles. Records from NCR derivations in anaesthetized subjects showed that wave N7 was followed by a further event (N10) localized on the scalp contralateral to the stimulus and by a few slow waves. Wave N10 could also be recorded, in the absence of earlier events, from the VR derivation contralateral to the stimulus. All the responses recorded in these patients could be considered of neurogenic origin because curarization abolished any reflex activation of muscles. All the waves following W3 are of postsynaptic nature and, on the basis of their distribution and latency, we suggest that P4, N5, P6, N7 and N10 have their respective origins in the trigeminal nucleus, trigeminal lemniscus, thalamus, thalamic radiation and cortical projection of the stimulated area. It was also demonstrated that stimulation of lips and gums fails to evoke any neural event recordable from the scalp.

Anesthesia↗