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Biomedical subjects

M Meglio

Publications and source records attributed to M Meglio.

At least 19 recordsLinked to original sources
PubMed2005

Retrospective analysis of variables favouring good surgical outcome in posterior epilepsies.

AIM: to determine variables favouring good surgical outcome in posterior epilepsies. METHODS: Fourteen patients submitted to epilepsy surgery were included in the study. The epileptogenic zone was located in temporo-parieto-occipital areas as assessed by both invasive and non-invasive pre-surgical evaluation. Several variables (age at first seizure; age at surgery; disease duration; type, frequency and clinical semiology of seizures; presence of lesion; scalp ictal and interictal EEG; localization and extension of epileptogenic zone; completeness of surgical resection) were compared (Fisher's exact test) with freedom from seizures to determine whether surgical outcome (Engel's classification) could be related to any of them. RESULTS: Seven patients were seizure free (Ia) and very satisfying results were obtained for 3 patients (2 Ib, 1 Ic). New post-surgical visual deficits occurred only in 3 patients. Surgical outcome was related significantly to two variables: scalp ictal EEG (focal versus non-focal; p: 0.014) and completeness of surgical resection of epileptogenic zone (p: 0.0023). A significant trend towards a better outcome for focal interictal intracranial activity versus a non-focal one (p: 0.07) was found. CONCLUSIONS: The correlation between completeness of epileptogenic zone resection and surgical outcome suggests that a presurgical protocol, allowing a precise definition of the area of resection, could help in obtaining more satisfying results in posterior epilepsies.

Adolescent↗
PubMed2004

Effects of vagus nerve stimulation on cortical excitability in epileptic patients.

Vagus nerve stimulation (VNS) is used as adjunctive treatment for medically refractory epilepsy, but little is known about its mechanisms of action. The effects of VNS on the excitatory and inhibitory circuits of the motor cortex were evaluated in five patients with epilepsy using single- and paired-pulse transcranial magnetic stimulation (TMS). Patients were examined with the stimulator on and off. VNS determined a selective and pronounced increase in the inhibition produced by paired-pulse TMS with no effects on the excitability by single-pulse TMS.

Adult↗
PubMed2004

Comparison of descending volleys evoked by transcranial and epidural motor cortex stimulation in a conscious patient with bulbar pain.

OBJECTIVE: To compare the pattern of activation of motor cortex produced by transcranial magnetic stimulation and epidural electrical stimulation. METHODS: The spinal volleys evoked by transcranial magnetic stimulation and epidural electrical stimulation over the cerebral motor cortex were recorded from an electrode inserted into the cervical epidural space of one conscious subject who also had a cortical epidural electrode over the motor area. The volleys were termed D- and I-waves according to their latency. Magnetic stimulation was performed with a figure-of-eight coil and the induced current flowed either in a postero-anterior (PA) or in latero-medial (LM) direction. RESULTS: At active motor threshold intensity LM magnetic stimulation evoked a D wave whereas PA stimulation evoked an I(1) wave with later I waves being recruited at increasing stimulus intensities. Electrical epidural stimulation evoked both a D wave and I waves. However, the D wave evoked by electrical epidural stimulation had a longer latency than the LM D wave, suggesting either a more proximal site of activation of the pyramidal axon or activation of slightly faster conducting set of corticospinal fibres by LM stimulation. The I3 wave evoked by electrical epidural stimulation also had a longer latency than the PA I3-wave CONCLUSIONS: Epidural stimulation of the motor cortex can produce repetitive excitation of corticospinal neurones. The order of recruitment of the volleys, and the latency of the D and I3 waves may be slightly different to that seen after transcranial magnetic stimulation. SIGNIFICANCE: Our findings suggest that there may be subtle differences in the populations of neurones activated by the two forms of stimulation.

Consciousness↗
PubMed2004

Direct recording of the output of the motor cortex produced by transcranial magnetic stimulation in a patient with cerebral cortex atrophy.

OBJECTIVE: To examine the descending motor activity evoked by transcranial magnetic stimulation (TMS) in a chronic alcoholic patient with a slight atrophy of the peri-central cortex and compare with that observed in neurologically intact subjects. METHODS: EMGs from the first dorsal interosseous (FDI) muscle, and descending activity from an electrode implanted in the high cervical epidural space for relief of pain were recorded after TMS of the hand area of motor cortex. A figure-of-8 coil was used to induce either a posterior-anterior (PA) or a latero-medial (LM) flow across the central sulcus. RESULTS: In intact subjects, LM stimulation evoked the earliest volley, which we termed a D wave. This was followed by later, presumed I waves at intervals of about 1.5 ms. At a stimulus intensity of 120% resting threshold (RMT), up to 5 I waves were seen. PA stimulation rarely evoked D waves at intensities up to 120% RMT, but 3 or 4 I waves were visible in all subjects. The patient had an increased resting threshold, and the descending volleys were dominated by a D wave. I waves were unclear, with two possible small peaks at 5.5 and 7.2 ms. CONCLUSIONS: The lack of I waves in the patient was probably due to an impairment of interneuronal circuitry in the context of the brain damage related to chronic alcohol abuse, and is consistent with a trans-synaptic origin of the I waves in humans. The intact D wave is consistent with the assumption that the D wave represents direct stimulation of the axons of intact corticospinal neurones in the subcortical white matter. The patient's increased RMT reflects the fact that usually multiple descending volleys are needed to discharge resting spinal motoneurones.

Alcoholism↗
PubMed2003

Craniocervical junction instability: instrumentation and fusion with titanium rods and sublaminar wires. Effectiveness and failures in personal experience.

BACKGROUND: The aim of the study was to evaluate the effectiveness, pitfalls and failures of instrumentation and fusion with titanium wires and rods in 12 h patients with craniovertebral junction instability. METHODS: Among nine adult patients (mean age 48.11 years) with craniovertebral junction instability, four had basilar impression, three metastatic disease, one rheumatoid arthritis and one Down's syndrome. Three children (mean age 7.33 years) with genetic (Down's syndrome, 2 cases) and metabolic (mucopolisaccarydoses type IV, i.e. Morquio Syndrome, 1 case) disease were studied as well. Each patient underwent preoperative radiological evaluation by means of X-Ray, CT scan and MRI of the craniocervical region. Occipitocervical instrumentation with a titanium U-shaped wired rod was performed in each patient. Autologous bone fusion was performed in all but the two cancer patients, in whom polymethylmetacrylate was used. Postoperatively, all the patients used an external orthosis for 3-6 months. Post-operative X-Ray, CT and MRI were performed on each patient. The Frankel clinical scale was used to asses the outcome at follow-up which ranged from 1 to 10 years. At maximum follow up, there was either clinical improvement or stabilization recorded in all but one patient. This patient with basilar impression transiently worsened from grade D to C and a spinal cord lesion was already evident before the operation on MRI examination. INTERPRETATION: The effectiveness of surgical management of craniovertebral junction instability by instrumentation and fusion was demonstratedly in our experience. Nevertheless, the choice of the surgical technique should be made with caution when a spinal cord lesion is revealed by preoperative neuroimaging studies.

Adult↗
PubMed2003

Subacute clinical onset of postraumatic myelopathy.

BACKGROUND: Subacute neurological deterioration unrelated to mechanical instability is a rare event. CASES REPORT: The authors describe two patients with subacute neurological deterioration unrelated to mechanical instability, which occurred 24 hours after spinal cord injury.The phenomenon could not be prevented by steroid therapy carried out either before or after the onset of clinical signs. An early surgical decompressive procedure performed in one of the two patients, failed to reverse the clinical symptomatology. FINDINGS: In the first case, temporal evolution of the neurological deterioration suggested a venous thrombosis with secondary congestive ischemia, whereas ischemia involving the anterior spinal artery seems to account for the deterioration observed in the second patient. INTERPRETATION: Spinal cord haemodynamics plays the main role in mediating the onset of descending subacute posttraumatic myelopathy. The cure and the prevention of the secondary vascular injury still remains unknown.

Acute Disease↗
PubMed2002

Hypoflow and hyperflow in diffuse axonal injury. Prognostic and therapeutic implications of transcranial Doppler sonography evaluation.

BACKGROUND: In the present report we describe the results of a study aimed at evaluating the cerebral haemodynamics and the neuroradiological findings observ-ed in 7 consecutive patients, 4 adults and 3 children (6, 8 and 10 years old), affected by diffuse axonal injury (DAI). METHODS: All the patients were admitted to the Paediatric or Adult Intensive Care Unit with GCS scores less than 8 after a severe brain injury. Serial head CT scan and trans-cranial Doppler sonography (TCD) examinations were carried out in all patients; MRI was carried out in the paediatric patients only. TCD of the middle cerebral arteries was performed through the temporal bone window. In 6 cases (2 paediatric) diuretic osmotic therapy was immediately administered and in 6 cases (3 paediatric) barbiturates and hyperventilation were also used. RESULTS: Hyperflow, variably responsive to barbiturate therapy of vasoparalysis, was observed in all paediatric patients and in 3 adult subjects (85.7%: 6 out of 7 pa-tients) by means of TCD. CONCLUSIONS: Observation of these phenomena allowed us to modify the pharmacological treatment and/or perform external cerebrospinal fluid (CSF) drainage (4 cases). Compartimental hyperflow TCD pattern was evident in 1 patient. Although the limited number of patients in our series does not allow definitive conclusions, we strongly believe that TCD monitoring is an useful tool in planning surgical strategy in patients with DAI.

Accidents, Traffic↗
PubMed2001

Descending spinal cord volleys evoked by transcranial magnetic and electrical stimulation of the motor cortex leg area in conscious humans.

1. Descending corticospinal volleys evoked after transcranial magnetic or electrical stimulation of the leg area of the motor cortex were recorded from an electrode in the spinal epidural space of six conscious patients who had electrodes implanted for treatment of chronic pain, and from one anaesthetised patient undergoing surgery for a spinal tumour. 2. At threshold, the shortest-latency volley (L1 volley) was evoked by stimulation with an anode 2 cm lateral to the vertex. Anodal stimulation at the vertex also elicited a volley at this latency in two patients, but in the other patients the first volley evoked appeared 1-1.3 ms later (L2 volley), at the same latency as the initial volley evoked by magnetic stimulation. High-intensity stimulation of any type could evoke both the L1 and L2 waves as well as later ones (L3, L4, etc.) that had a periodicity of about 1.5 ms. 3. Voluntary contraction increased the amplitude of the L2 and later volleys, but had no effect on the L1 volley. 4. Intracortical inhibition between pairs of magnetic stimuli resulted in clear suppression of the L4 and later waves. The L2 and L3 waves were unaffected. 5. In the anaesthetised patient the L1 volley occurred 1.7 ms later than the volley produced by transmastoid stimulation of the corticospinal pathways in the brainstem. 6. The L1 volley is likely to be a D wave produced by the direct activation of pyramidal axons in the subcortical white matter; the L2 and later volleys are likely to be I waves produced by the trans-synaptic activation of corticospinal neurones. The implication is that electrical stimulation with an anode at the vertex is more likely to evoke I waves preferentially than stimulation over the hand area. A more secure way to ensure D wave activation of corticospinal fibres from the leg area is to place the anode 2 cm lateral to the vertex.

Adult↗
PubMed2001

Spinal cord stimulation and early experimental cerebral spasm: the "functional monitoring" and the "preventing effect".

BACKGROUND: Clinical and experimental data on cerebral blood flow (CBF) changes during spinal cord stimulation (SCS) were published since 1986. The aims of the present work are: 1. To find an experimental model of reliable, simple and in vivo monitoring of "early" basilar artery spasm after subarachnoid haemorrhage (SAH) and 2. To investigate the effects of cervical spinal cord stimulation (CSCS) on it. Vasospasm due to SAH is both "acute" and "recurrent". Early spasm occurs within minutes of the SAH. its duration is approximately 1 hour. The need of different morphological and haemodynamic methods to evaluate experimental early spasm is reported. To overcome intracranial surgical manipulations and biological effects of contrast and fixation media we designed a model that allows "in vivo" functional monitoring of basilar blood flow far away from the spasm without direct surgical and chemical interference. Subsequently we investigated the effects of CSCS on the new model of "functional monitoring" of the "early" cerebral vasospasm. METHOD: 29 adult Burgundy rabbits were studied. Group 1: under homeostatic monitoring, "on-line" carotid blood flow (carotid BF) changes produced by SAH in cisterna magna of 12 (plus 5 sham treated) animals were studied from the common carotid artery after external carotid artery occlusion before, during SAH and up to the end of the experiments. All the animals underwent digital subtraction cerebral panangiography (CPA) after SAH obtaining a significant increase of carotid BF only when basilar vasospasm was shown by CPA. Carotid BF increase during basilar vasospasm was defined "functional monitoring" of early spasm. Group 2: Twelve animals wearing a cervical epidural electrode underwent carotid BF "functional monitoring" of early basilar spasm before and during CSCS. FINDINGS: Carotid BF changes during CSCS occurred in 10 animals. No carotid BF changes (i.e. no basilar vasospasm) occurred after SAH up to the end of the experiments in all the stimulated animals. INTERPRETATION: CSCS is able to prevent "early spasm" due to SAH in all the animals studied with the new model of "functional monitoring" described, independently from the occurence and the sign for stimulation-induced carotid BF variations. The role and the limits of reversible functional sympathectomy in mediating the effect of CSCS on early vasospam are discussed.

Acute Disease↗
PubMed2001

Spinal cord stimulation and cerebral blood flow in stroke: personal experience.

Spinal cord stimulation (SCS) can increase cerebral blood flow (CBF) and improve stroke patients. In order to better understand the haemodynamic changes underlining the clinical improvement, we have studied with transcranial Doppler (TCD), SPECT and NIRS 18 patients harbouring a stroke. SPECT Group: An increase of regional CBF during SCS was measured far from the stroke areas in 9 patients, further decrease in CBF was found in 2, no changes in 1. TCD Group: An increase of CBF velocities during SCS was found in 4 patients, no changes in 6, a decrease in 1. NIRS Group: Data consistent with and increase in CBF were obtained during SCS in the only patient undergone such a study. In 6 patients studied with different techniques, data obtained fitted only in 2 patients. In 3 patients no changes in TCD faced with changes in SPECT. In one case an improvement in TCD was evident in the left while an improvement of SPECT was shown in the right site. SCS is a valid therapeutic tool in stroke patient even if, as matter of fact, parallelism between clinical and haemodynamic changes during SCS is not demonstrated in our patients, rising the question on the role of ischemic penumbra in mediating clinical improvement.

Adult↗
PubMed2001

Protective effect of spinal cord stimulation on experimental early cerebral vasospasm. Conclusive results.

In this study we investigate the effects of cervical spinal cord stimulation (cSCS) on experimental 'early spasm' in rabbits as described in personal previous experience (Acta Neurochir 2001;143:177-185). Twenty-four adult red Burgundy rabbits wearing a cervical epidural electrode underwent cerebral blood flow (CBF) and functional monitoring of early basilar spasm before and during cSCS. CBF changes, as a consequence of cSCS, occurred in 20 control animals. No CBF changes, consistent with no basilar artery vasospasm, occurred after subarachnoid haemorrhage (SAH) up to the end of the experiments in all the stimulated animals. The role of reversible functional sympathectomy in mediating the effect of spinal cord stimulation on early spasm is discussed. cSCS is able to prevent 'early spasm' due to SAH in all the animals studied, independently from the occurrence and the sign of stimulation induced CBF variations.

Animals↗
PubMed2001

Spinal cord stimulation prevents the effects of combined experimental ischemic and traumatic brain injury. An MR study.

Spinal cord stimulation (SCS) interferes with cerebral blood flow (CBF). In this paper we try to evaluate the possible preventing effect of SCS in an animal model of combined ischemic and traumatic injury. We studied 20 New Zealand rabbits undergoing ligature of both carotid arteries and a right hemispheric craniectomy and about 3 h mechanical injury (200 mg) over the dura. In 10 animals (control group) SCS was not delivered; in 10 (SCS group) cervical SCS was started 20 min after arterial ligation and before the craniectomy and the mechanical injury. MR examination was performed in all the animals at the end of the experiments. Compared to the control group none but one of the SCS showed lesional pattern far from the craniectomy suggesting a 'preventing' effect of SCS on the secondary damage associated with our model combined ischemic and traumatic brain injury.

Animals↗
PubMed2001

Spinal cord stimulation in patients with refractory anginal pain and normal coronary arteries.

BACKGROUND: Spinal cord stimulation (SCS) has been shown to be effective in patients with refractory angina and coronary artery disease. No previous study assessed the clinical effects of SCS in patients with refractory angina who present angiographically normal coronary arteries. METHODS: SCS was performed in 7 patients (4 men, 3 women, mean age 59.3 +/- 11 years) with refractory angina and normal coronary arteries. Clinical status was assessed 1 month after SCS device implantation and at a mean follow-up of 11 months (range 2-17 months) by: 1) an estimate of the number of anginal attacks and nitrate consumption in the 2 weeks prior to implantation and to follow-up visits; 2) a score of quality of life by a visual analogic scale; 3) a five-item questionnaire assessing effort angina and satisfaction with treatment; 4) treadmill exercise testing. RESULTS: At the last follow-up the number of anginal episodes (p < 0.001) and nitrate consumption (p < 0.004) were both reduced by SCS. Visual analogic scale score improved from 2.1 +/- 0.98 to 9.0 +/- 0.9 (p < 0.001) at 1 month and to 6.4 +/- 2.3 (p < 0.01) at the last follow-up. Questionnaire analysis showed that mild (p = 0.006) and moderate (p = 0.000) physical activity, as well as patient satisfaction with anginal status (p = 0.000) and with current treatment (p = 0.000) all improved by SCS. Finally, time to 1 mm ST segment depression, time to angina, and exercise duration were all prolonged by SCS. CONCLUSIONS: Our data point out that SCS may considerably improve anginal symptoms and exercise tolerance in a significant number of patients with refractory angina and normal coronary arteries and therefore it should be considered as a valuable treatment option in this group of patients.

Electric Stimulation Therapy↗
PubMed2001

Alternative technique for subclavian vein cannulation.

BACKGROUND: Subclavian vein catheterism, a commonly used methodology in ICU, is not devoid of complications, even some serious ones (Pneumothorax 0.5%). METHODS: The authors propose an alternative technique based on the use of an introducer needle bent on its own axis to form an arch with its concavity turned towards the Quincke point. On searching the blood vessel, once the subclavian plane has been reached, the needle advancement towards the jugular fosse happens by following the needle curvature. In this way the operator can keep the needle on a plane parallel to the cutaneous one, and all the complications due to involuntary exceeding of the costal plane are avoided. The response of this new technique in 110 patients (study group) is compared through a retrospective study, to 100 patients with whom the standard technique has been used (control group). RESULTS: The study group has presented a significant reduction both of total complications (p<0.05) and of total failures (p< 0.01). CONCLUSIONS: Such results, although pertinent to a still limited study, testify to an improvement in terms of security and efficacy, with the new alternative technique without an increase in costs.

Adult↗
PubMed2000

Direct demonstration of the effect of lorazepam on the excitability of the human motor cortex.

OBJECTIVES: The present study explored the effects of lorazepam, a benzodiazepine with agonist action at the GABA(A) receptor, on human motor cortex excitability as tested using transcranial magnetic stimulation. METHODS: We recorded directly the descending volley evoked by single and paired transcranial magnetic stimulation from the spinal cord of a conscious subject with a cervical epidural electrode before and after a single oral dose of lorazepam. We evaluated the effects of lorazepam on the descending volleys evoked by a single magnetic stimulation and paired cortical stimulation using the intracortical inhibition paradigm (subthreshold conditioning stimulus) and the short latency intracortical facilitation paradigm (suprathreshold conditioning stimulus). RESULTS: Using a single magnetic stimulus lorazepam decreased the amplitude of the later I waves in the descending volley; this was accompanied by a decrease in the amplitude of the evoked EMG response. Using the intracortical inhibition paradigm lorazepam increased the amount of corticocortical inhibition, particularly at 4 and 5 ms interstimulus intervals. There was no effect on the amount of facilitation observed in the short latency intracortical facilitation paradigm. CONCLUSIONS: The present findings provide direct evidence that lorazepam increases the excitability of inhibitory circuits in the human motor cortex.

Aged↗
PubMed1999

Intraoperative motor evoked potentials monitoring in spinal neurosurgery.

Neurological damage may follow even a technically accurate spinal surgery. The intraoperative monitoring of neurological functions put at risk by the operation is a method utilized to correctly identify the topography of neural structures and to avoid surgical insults. SEPs monitoring is 20 year old, and only recently direct motor tract monitoring has become possible. Transcranial electrical motor cortex stimulation with single pulses or with short trains of stimuli and recording of the evoked responses from the spinal epidural space (D-waves) and from limb muscles is a reliable and safe technique for monitoring corticospinal tract activity even under general anesthesia. The method has a solid theoretical experimental background. Its clinical application has demonstrated high sensitivity and specificity. Intraoperative MEPs monitoring is nowadays considered indispensable during spinal neurosurgery.

Animals↗
PubMed1998

[Anesthesiologic and surgical problems in adenotonsillectomy in pediatric patients. Our current trend].

AIM: To verify, in dissection adenotonsillectomy (AT) performed in Rose position under general anaesthesia with oro-tracheal intubation, the following: 1) the ability of tramadol to produce an effective intra- and postoperative analgesia without any considerable side effects or interferences with the normal post-surgical course of the operation; 2) the possibility of obtaining, thanks to mivacurium, a myoresolution closer both to surgical times of the operation and to the necessity of a fast recovering of the pharyngo-laryngeal reflexes. EXPERIMENTAL DESIGN: A perspective and retrospective clinical study. SETTING: University clinic department (operating room and facility). PATIENTS: 110 patients submitted to adenotonsillectomy, aged 4-10, belonging to the I-II ASA categories and not taking any drug for at least 30 days. INTERVENTIONS: Intravenous pre-medication with tramadol 2 mg/kg; myoresolution with mivacurium 0.2 mg/kg; postoperative analgesia with tramadol 2 mg/kg i.m. one hour after the first administration and, with an equivalent oral dose of tramadol, six hours later. MEASUREMENTS: During surgery: ECG, HR, Sat HbO2, non-invasive arterial blood pressure; after surgery: clinical evaluation of pain, through a three-point scale, and of the surgical course. RESULTS: Good analgesical level both during and after surgery; myoresolution especially suitable to adenotonsillectomy duration and characteristics; no considerable complications. CONCLUSIONS: Tramadol intra- and postoperative analgesia and mivacurium myoresolution represents, in personal opinion, an efficient approach to dissection adenotonsillectomy performed in children under general anaesthesia.

Adenoidectomy↗