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Biomedical subjects

M Meglio

Publications and source records attributed to M Meglio.

At least 55 records · Page 3Linked to original sources
PubMed1991

Antinociceptive activity of intracerebroventricular lysine acetylsalicylate: an experimental study.

We investigated the antinociceptive activity of Lysine Acetylsalicylate (LAS) after intracerebroventricular (icv) injection in experimental animals. The effect on tonic pain was studied by means of the Formalin test on 140 male Swiss mice. In a first group of animals icv LAS was injected at different doses (0.25-0.5-1 mg in saline solution 5 microliters). A second group received icv morphine 1 microgram in 5 microliters saline, and finally a third control group received icv 5 microliters saline. The effect of the compounds on the Formalin test was evaluated under blind conditions. Icv LAS had no effect on the nociceptive behaviour at doses of 0.25 and 0.5 mg, while a reduction of the licking time was evident after the injection of 1 mg of the drug. The time course and the degree of the analgesic effect of icv LAS was investigated and compared to the effect of icv morphine.

Analgesics↗
PubMed1991

Spinal cord stimulation and cerebral haemodynamics.

An increase of regional cerebral blood flow (rCBF) has been shown to occur in man during spinal cord stimulation (SCS) by Hosobuchi (1986) and by Meglio et al. (1988) using the 133-Xenon wash-out technique. In this paper we report the effects of SCS on CBF as measured by two different techniques: 8 patients were studied with the 133-Xe method and 28 with the transcranial doppler sonography (TCD), in two cases both studies were performed. The aim of our study was to: 1-verify the effect of SCS on CBF, 2-compare observations made by two different methods, and 3-evaluate a possible correlation between the stimulated spinal segmental level and the modification of CBF. The results of our study confirm that SCS interacts with the mechanisms of regulation of CBF. The stimulation of different spinal cord levels in the same patient can produce different effects and such effects are reproducible. An increase of CBF is more likely to occur with the stimulation of the cervical spinal cord. In patients studied by both methods the sign of CBF changes induced by SCS was the same. Finally, in two patients the effect of SCS on CO2 autoregulation was studied with TCD. The results of such a study, although preliminary, suggest that CO2 and SCS have a competitive effect upon the mechanisms of regulation of CBF.

Blood Flow Velocity↗
PubMed1991

Cerebral hemodynamics during spinal cord stimulation.

An increase of cerebral blood flow (CBF) during spinal cord stimulation (SCS) has been shown in man using the 133Xenon inhalation technique. We report the effects of SCS on cerebral hemodynamics studied with transcranial Doppler sonography (TCD). Twenty-six patients with epidural electrodes implanted at the cervical level (11 patients) and at the thoracic level (15 patients) were investigated with recordings of CBF velocity in the middle cerebral arteries before and during SCS. Sixty-three and two-thirds percent of patients with cervical stimulation and 29.4% of patients with thoracic stimulation showed a decrease of cerebral vascular resistance simultaneously with an increase of the velocity of CBF.

Blood Flow Velocity↗
PubMed1990

Microvascular decompression versus percutaneous procedures for typical trigeminal neuralgia: personal experience.

This study includes 127 patients treated for typical trigeminal neuralgia, 74 of whom underwent a percutaneous microcompression (PMC), 33 a radiofrequency thermocoagulation (RFT) and 20 were explored for microvascular decompression (MVD). A mean follow-up of 24 months was reached by all the groups. Pain relief was evaluated as an 'all or none' effect. At hospital discharge, pain had disappeared in 93.2% of the patients treated with PMC, in 81.8% of those treated with RFT, and in 85% of the MVD group. At 24 months the effect was maintained by 57.2% of the PMC group, 57.6% of the RFT, and by 75% of the MVD group. Marked dysesthesia was reported by 6.7% of the patients treated with PMC, and by 24.2% of those who received a RFT. Impairment of masticatory function was observed in 10% of the PMC patients. Ipsilateral hypoacusia and transient IV nerve palsy in 1 patient was the only major complication after MVD.

Electrocoagulation↗
PubMed1989

Spinal cord stimulation (SCS) in the treatment of postherpetic pain.

SCS is considered to be of poor value in treating postherpetic pain. We have retrospectively analyzed the results obtained in 10 patients suffering from postherpetic neuralgia. An epidural electrode was implanted, aiming the tip in a position where stimulation could produce paraesthesiae over the painful area. At the end of the test period 6 out of 10 patients reporting a mean analgesia of 52.5% underwent a permanent implant. At mean follow-up (15 months) all the 6 patients were still reporting a satisfactory pain relief (74% of mean analgesia). These figures remained unchanged at the next follow-ups (max 46 months). The result of SCS in our patients, although positive in only 60% of them, are remarkably stable with time. We therefore recommend a percutaneous test trial of SCS in every case of postherpetic neuralgia resistent to medical treatment.

Aged↗
PubMed1989

Spinal cord stimulation (SCS) in deafferentation pain.

Spinal cord stimulation is considered to be ineffective in relieving deafferentation pain. We have retrospectively analyzed the results obtained in a series of 41 patients. Sixteen suffered from pain associated with an incomplete traumatic spinal lesion, 15 from a posttherapeutic neuralgia, and 10 from pain due to root and/or nerve damage. At the end of the test period, 43.7% of the patients with paraplegic pain, (40% of those with peripheral deafferentation pain and 66.6% of the ones with postherapeutic neuralgia), reported satisfactory pain relief and were connected to a chronic stimulation system. At mean follow-up (15 months), only 20% of the patients of the first two groups reported sufficient pain relief. In the postherapeutic group the figure of responders was unchanged. The mean analgesia achieved was 70%. From this analysis we conclude that the results achieved in the postherapeutic pain patients, although positive in only 66% of them, are remarkably stable with time. Therefore, we recommend a percutaneous test trial of SCS in every case of postherapeutic pain resistant to medical treatment.

Adult↗
PubMed1989

Spinal cord stimulation (SCS) in spastic hemiparesis.

Thirteen patients with post-stroke spastic hemiparesis underwent a percutaneous test trial of spinal cord stimulation (SCS) in order to modify their motor disturbances. Clinical evaluation based on Albert's motor scale and neurophysiological evaluation consisting of surface EMG during voluntary, involuntary, and reflex motor activity were performed before and during SCS. At the end of the test period, eight patients showed a significant improvement in their motor performance. The EMG analysis confirmed the clinical data. SCS was followed by a reduction or disappearance of synergic coactivation with better agonist-antagonist coordination, a decrease of clonus both in duration and spreading, and better endurance. The effect on motor control did not increase with time after the first month of SCS, but was long lasting (mean follow-up: 2 years). There was a correlation between sensory deficit and motor outcome suggesting that the enhancement of sensory input put into play by SCS and the consequent development of new sensory-motor integration might be responsible for the improvement in motor performance.

Adult↗
PubMed1989

Effect of spinal cord stimulation on motor performances in hemiplegics.

Spinal cord stimulation (SCS) was performed in 11 patients with stabilized spastic hemiparesis due to cerebrovascular ischaemic accident in order to improve their motor performances. The patients were studied before and after 5-7 days of stimulation of the cervical cord according to the following protocol: (1) clinical evaluation based on assessment of the neurological status and on Albert's motor scale and (2) neurophysiological evaluation of reflex voluntary and involuntary motor activity, obtained by means of surface electromyography. Improvement in motor performance following SCS occurred in 7 of the 11 patients. The effect appeared to be particularly evident during specific voluntary movements and gait. Analysis of the electromyography recordings showed that SCS mainly broke down pathological patterns of voluntary movement and reduced agonist-antagonist coactivation and clonus. A relationship between motor outcome and status of the sensory function was noticed as well. We conclude that SCS may play a role in the motor rehabilitation of post-stroke patients with spastic hemiparesis, provided that a careful selection be made before surgery.

Adult↗
PubMed1989

Spinal cord stimulation in management of chronic pain. A 9-year experience.

Between 1978 and 1986, 109 patients with chronic pain underwent spinal cord stimulation (SCS) at the authors' institute as part of their pain treatment program. The results of SCS in these patients at the end of the test period and at the latest follow-up examination are analyzed in relation to the etiology of their pain. In 40 patients pain was associated with an obstructive peripheral vasculopathy, in 10 with a previous herpes zoster infection, in 15 with an incomplete traumatic spinal cord lesion, in nine with root and/or nerve damage, in 11 with cancer, and in 19 with previous back surgery. The etiology of the pain in five patients was uncertain. This experience supports the conclusion that the best indications for SCS are vasculopathic pain and post-herpetic neuralgia. No clinical usefulness was found for SCS in cancer pain or in central deafferentation types of pain.

Adult↗
PubMed1989

[Stimulation of the spinal cord in peripheral vasculopathies].

Spinal cord stimulation (SCS) by means of percutaneously implantable epidural electrodes was utilized for the treatment of benign pain of different etiologies. The technique was particularly useful when dealing with pain due to peripheral obstructive vascular disease. Improvement of claudication and of trophic lesions occurred as well. Different techniques were utilized in order to evaluate changes in peripheral blood flow during SCS. The results of our studies, even though not conclusive, suggest that SCS induces an increase in peripheral blood flow. A reduction of sympathetic out-flow during SCS was demonstrated by our group in studies of Heart Rate in man. Such so called "Reversible Functional Sympathectomy" can, at least partially, account for the results of SCS in peripheral vasculopathies.

Arterial Occlusive Diseases↗
PubMed1987

Spinal cord stimulation improves motor performances in hemiplegics: clinical and neurophysiological study.

We studied the effects of spinal cord stimulation (SCS) on motor performances in patients with spastic hemiparesis due to cerebrovascular ischemic accident. 11 patients were evaluated before and after 7 days of SCS by means of the Albert's motor scale and a surface polyelectromyography. SCS significantly improved motor performances in 63% of the patients. It reduced agonist-antagonist coactivation and clonus. Such an effect was particularly evident during voluntary movements and gait.

Electric Stimulation Therapy↗
PubMed1987

Percutaneous microcompression of the gasserian ganglion: personal experience.

The effectiveness of percutaneous microcompression of the gasserian ganglion, performed according to the technique proposed by Mullan and Lichtor, was evaluated in 74 patients affected by essential trigeminal neuralgia and compared to the results obtained with the RF thermocoagulation of Sweet and Wepsic. Similar results were obtained with the two methods but adverse side-effects were less common with microcompression. It is concluded that the microcompression should be recommended as a first choice among the different percutaneous procedures in the treatment of trigeminal neuralgia.

Electrocoagulation↗
PubMed1987

The 'foramen ovale electrode': a safe tool to study temporal lobe epilepsy.

Following the description by Wieser et al. (1985) of the use of a foramen ovale electrode to record from mesial temporal structures the authors describe an alternative electrode equipped with radial tines to make it self-retaining. A helical section provides flexibility along the electrode's longitudinal axis preventing displacement of the tip during jaw movements. Clinical and detailed neurophysiological examinations failed to demonstrate any evidence of motor or sensory trigeminal nerve dysfunction and no complications were encountered.

Electrodes, Implanted↗
PubMed1987

Intracranial stimulation of the trigeminal nerve in man. III. Sensory potentials.

Percutaneous electrical stimulation of the trigeminal root was performed in 18 subjects undergoing surgery for idiopathic trigeminal neuralgia or implantation of electrodes into Meckel's cave for recording of limbic epileptic activity. All subjects had normal trigeminal reflexes and evoked potentials. Sensory action potentials were recorded antidromically from the supraorbital (V1), infraorbital (V2) and mental (V3) nerves. In the awake subject, sensory potentials were usually followed by myogenic artifacts due to direct activation of masticatory muscles or reflex activation of facial muscles. In the anaesthetised and curarised subject, sensory potentials from the three nerves showed 1.4-2.2 ms onset latency, 1.9-2.7 ms peak latency and 17-29 microV amplitude. Sensory conduction velocity was computed at the onset latency (maximum CV) and at the peak latency (peak CV). On average, maximum and peak CV were 52 and 39 m/s for V1, 54 and 42 m/s for V2 and 54 and 44 m/s for V3. There was no apparent difference in CV between subjects with trigeminal neuralgia and those with epilepsy. A significant inverse correlation was found between CV and age, the overall maximum CV declining from 59 m/s (16 years) to 49 m/s (73 years). This range of CV is compatible both with histometric data and previous electrophysiological findings on trigeminal nerve conduction. Intraoperative intracranial stimulation is also proposed as a method of monitoring trigeminal function under general anaesthesia.

Action Potentials↗
PubMed1986

Spinal cord stimulation affects the central mechanisms of regulation of heart rate.

The effect of spinal cord stimulation (SCS) on heart rate (HR) was studied in 25 patients without cardiological symptoms, who were undergoing SCS for various reasons. HR at rest significantly decreased during SCS. Physiological and pharmacological maneuvers of sympathetic and parasympathetic activation or blockade before and during SCS indicate that SCS interferes with the central mechanisms of regulation of HR mainly by inducing a functional sympathectomy, and that such an effect is mediated by an action on spinal cord ascending fibers.

Adult↗
PubMed1986

Epidural recordings of electrical events produced in the spinal cord by segmental, ascending and descending volleys.

Epidural electrodes implanted for a percutaneous trial of therapeutic spinal cord stimulation were used to record electrical events evoked by the stimulation of peripheral nerves or of the spinal cord itself. The data collected in patients with no neurological deficit were analyzed in order (1) to check the consistency between epidural and surface recordings, (2) to get information on the genesis of such potentials, and (3) to demonstrate the feasibility of complex neurophysiological studies by means of epidural electrodes. Spinal cord potentials evoked by segmental volleys were recorded at cervical levels with the recording electrodes anterior, lateral and posterior to the spinal cord. The refractory period of the evoked potentials has been studied as well. Responses to stimulation of the tibial nerve were obtained at T11-12 vertebral level with posterior epidural electrodes. Segmental cervical potentials were characterized by a P10, N11, N13/P13 followed by a slow positivity/negativity. A response of similar waveform, but with different peak latencies, was recorded at segmental levels following tibial nerve stimulation. Such a response showed an increasing number of spikes while ascending along the spinal cord. Maximum conduction velocities in the cord were between 65 and 85 m/s. Our epidural recordings are similar to those obtained from the skin, but with a greater amplitude and waveform resolution. Furthermore, the use of epidural electrodes made it feasible to perform complex examinations of sensory function (i.e., the study of orthodromic and antidromic conduction along the dorsal cord and of the influence of a single dorsal cord volley on the segmental cervical potential). Finally, the genesis of the potentials recorded is discussed.

Adult↗