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Biomedical subjects

M Caramia

Publications and source records attributed to M Caramia.

At least 19 recordsLinked to original sources
PubMed2005

Cortical hyperexcitability in post-traumatic stress disorder secondary to minor accidental head trauma: a neurophysiologic study.

OBJECTIVE: We applied paired transcranial magnetic stimulation (pTMS) to patients with post-traumatic stress disorder (PTSD) secondary to minor accidental head trauma. Our purpose was to determine the potential abnormality of motor cortex excitability in this pathologic condition. METHODS: pTMS stimulation, according to the conditioning-test paradigm employing interstimulus intervals (ISIs) of 1-6 ms, was used to investigate intracortical inhibition in control subjects and patients with PTSD. The study population consisted of 14 patients who had developed PTSD following minor head trauma, 12 healthy volunteers without a clinical history of head trauma and 11 healthy subjects who had reported accidental minor head trauma 1-4 months before the study. This clinical electrophysiologic study was performed at the Department of Neuroscience, University of Rome "Tor Vergata." RESULTS: All patients with PTSD exhibited a significantly lower motor evoked potential (MEP) inhibition than controls at 2 ms, 3 ms and 4 ms ISI. The statistical analysis of the pTMS protocol showed a significant effect (F2,36 = 25.63, p < 0.001) of the factor "group," because patients with PTSD showed a mean conditioned MEP amplitude higher than that observed in both control groups for all 6 ISIs analyzed. The "ISI" factor was also significant (F5,180 = 89.85, Greenhouse-Geisser epsilon = 0.35; p < 0.001), with the mean conditioned MEP amplitude increasing from 22.5% to 127.8% as the ISI increased from 1 ms to 6 ms. Finally, the interaction of group with ISI was also significant (F10,180 = 8.97, p < 0.001), showing that the condition of PTSD secondary to head trauma was able to affect the MEP amplitude at different ISIs. CONCLUSIONS: Our results demonstrate that PTSD can give rise to abnormalities in intracortical inhibition. Our results provide further evidence that alterations in cortical inhibitory circuits may underlie specific forms of neuroticism in humans.

Adolescent↗
PubMed2004

Uric acid, phosphate and oxalate stones: treatment and prophylaxis.

Medical treatment for the most commonly encountered types of renal stones is described. Nowadays treatment for uric acid stones is well-defined: alkalinizing urine is easy with drugs that are sufficiently active and well enough managed. Relapse is avoided in a high percentage of patients. Medical treatment of phosphate or calcium stones is a more open question as results are far from satisfactory compared with intra- and extra-corporeal approaches which are often minimally invasive and well accepted by both patient and urologist. Relapses are not easy to control because prophylactic measures such as changes in lifestyle and diet are never activated or because they are adopted for a brief period of time. Water therapy is examined, with the choice of water depending on the type of stone, together with drug therapy. Drugs such as citrate, with or without magnesium, and thiazides are considered excellent for curing renal stones and relapses. Although medical therapy has a limited role in many types of stones, its use is decisive in some others.

Calcium Oxalate↗
PubMed2004

Lithiasic obstructive uropathy. Hydronephrosis characterization by magnetic resonance pyelography.

OBJECTIVES: The purpose of this study was to evaluate the role of magnetic resonance (MR) pyelography in patients affected by hydronephrosis due to ureteric stones, in order to identify a pyonephrotic condition. MATERIALS AND METHODS: In the last 3 years, 315 patients, who had originally been investigated by ultrasonography, were evaluated with MR pyelography in order to define the etiology of obstruction. In 67 patients hydronephrosis was referred as caused by lithiasis. RESULTS: MR pyelography not only confirmed urinary tract dilatation in all patients, but also identified grade and site of obstruction, both in acute dilatation (25 patients) and in chronic obstructions (42 patients). In 7 patients, MR pyelography documented pyonephrosis that was obviously confirmed by nephrostomic drainage. CONCLUSION: MR pyelography, made with ultrafast breath-hold sequences, has a great value in identifying hydronephrosis in patients with ureteric stones. Furthermore, it provides the chance to identify pyonephrosis requiring an immediate drainage of the kidney before major complications develop.

Adult↗
PubMed1998

Plasmapheresis in severe forms of myasthenia gravis.

In this study we introduce a new combination treatment of plasma exchange (PE) and high daily doses of prednisone for severe forms of myasthenia gravis (MG). The clinical efficacy of the combined therapy has been tested in 18 patients suffering from severe forms of MG. The protocol included 5 sessions of PE, performed in a range of 15 days, 1 session every 3 days, with concurrent administration of oral prednisone (1 mg/kg of body weight), starting at the first session of PE and given daily for at least 3 months. At the end of the entire cycle of PE, almost complete recovery (more than 90% of the initial clinical score) was obtained in 8 of 18 patients while an improvement between 60 and 90% of the initial score was achieved in 9 of 18 patients. An early improvement was noted 24 h after the beginning of plasmapheresis in 11 of 18 patients. No recurrence of symptoms was reported after 36 months of follow-up for 17 patients. The administration of steroid therapy was never followed by an early exacerbation of myasthenic symptoms as reported when it is administered in the absence of concomitant PE. According to our results, we can conclude that high doses of oral prednisone therapy in simultaneous association with PE lead to successful control of severe forms of MG, significantly superior to the therapeutic strategies until now adopted and reported in literature.

Administration, Oral↗
PubMed1994

[Gallbladder carcinoma. Our experience].

Carcinoma of the gallbladder is the most frequent neoplasm of the biliary tract. During the period between 1 January 1979 and 31 December 1991 a total of 1016 operations for cholecystectomy were performed by our Division of Surgery and 27 cases of gallbladder carcinoma were diagnosed. The symptoms were generally similar to those of benign hepatobiliary disorders. The diagnostic tests carried out did not allow a preoperative diagnosis of gallbladder carcinoma to be made. In the majority of cases diagnosis was a surprise following the histological analysis of the operated part. The prime therapy for these lesions is surgery. Since it is not possible to make an early diagnosis of this type of neoplasm, which in the majority of cases has a fatal prognosis, the authors consider that the finding of inveterate calculosis, large calculi and echographic thickening of the gallbladder wall represent indications for surgery even in the absence of major symptoms.

Adult↗
PubMed1988

Pre-movement facilitation of motor-evoked potentials in man during transcranial stimulation of the central motor pathways.

Motor evoked potentials (MEPs) following trans-cranial stimulation (TCS) through unifocal electric or magnetic impulses have been evaluated in the pre-movement period in 8 healthy volunteers. By utilizing a simple reaction time paradigm, progressive amplitude increments and latency decrements of MEPs have been demonstrated in the 100 ms preceding the onset of EMG activity in the muscle examined. By employing surface and depth recordings from various muscles of hand and forearm contralateral to the TCS, it was observed that in the 'early' period of pre-EMG facilitation (100-60 ms before EMG onset) TCS solely recruited the same low-threshold motor units which are fired first during self-paced contractions. In the 'middle and late' epochs of pre-EMG facilitation, TCS served when MEPs were recorded from a relaxed muscle, during TCS of progressively higher intensity. Multiple muscle recordings showed that pre-EMG facilitation was remarkably limited to the muscular group of the hand primarily involved in the intended movement.

Adult↗
PubMed1988

Enhancement of motor cortical excitability in humans by non-invasive electrical stimulation appears prior to voluntary movement.

The time course of facilitation of motor evoked potentials (MEPs) to transcranial electrical stimulation delivered at varying intervals near the onset of a voluntary ballistic movement was studied in 4 normal subjects. MEPs were recorded from the left thenar muscles to unifocal anodal stimulation of the right scalp overlying the hand motor area delivered every 8-10 sec. A click, occasionally associated with the scalp stimulation (P = 0.3-0.6), was the signal for the subject to make a brief thumb press on a piston at short latency. The timing of the scalp stimulus and the click was adjusted so that the former occurred approximately between 100 msec before and 100 msec after the onset of the voluntary movement signaled by the EMG in the thenar muscles. MEPs were not detected when the scalp was stimulated 80 msec or more before onset of voluntary movement and then appeared with increasing probability as the time interval before movement shortened. The amplitudes of MEPs in the 80-40 msec period preceding movement onset were small (less than 20% of maximum) and achieved maximum values 20 msec after movement onset.

Adult↗
PubMed1987

Central motor tract propagation in man: studies with non-invasive, unifocal, scalp stimulation.

Motor-evoked potentials (MEPs) to unifocal, anodal scalp stimulation have been recorded in 45 healthy volunteers from proximal and distal upper limb muscles. Optimal responses were obtained through a pericranial cathode consisting of 6 or more regularly spaced, interconnected plaques whose impedance was carefully balanced with that of a 0.8-cm2 stimulating anode on the scalp. Individual rectangular pulses with threshold intensity (70-86 mA) 100-200 microseconds in duration, with rise-decay times shorter than 50 microseconds resulted more efficient in eliciting individual MEPs in the target muscle. The foci of maximal response for hand and shoulder muscles were localized. The scalp-to-cervical cord conduction time along the motor tracts governing the hand muscles was 5.21 +/- 0.42 ms. This index was highly correlated with the subject's height and stable in time when repeatedly tested. Collision between orthodromically and antidromically propagated motor impulses was obtained by simultaneous stimulation of scalp and median nerve at wrist. Response facilitation was achieved by means of prestimulus voluntary contraction of the target muscle, continuous vibration of its tendon or scalp stimulation with paired shocks. Facilitation of MEPs was obtained by prestimulating the ipsilateral motor cortex 8-24 ms before the stimulation of the one contralateral to the target muscle. This was considered at least in part mediated by transcallosal connections. An efferent volley secondary to scalp stimulation was recorded for the nerve trunk with the near-nerve technique. Segmental and suprasegmental mechanisms underlying MEP facilitation provoked by phasic and tonic contractions of the target muscle have been investigated.

Adult↗
PubMed1987

Non-invasive evaluation of input-output characteristics of sensorimotor cerebral areas in healthy humans.

The topography of scalp SEPs to mixed and sensory median nerve (MN) and to musculocutaneous nerve stimulation was examined in 20 healthy subjects through multichannel (12-36) recording in a 50 msec post-stimulus epoch. MN-SEPs in both frontal leads were characterized by an N18, P20, N24, P28 complex showing maximal amplitude at contralateral parasagittal sites. This was sometimes partly obscured by a wide wave N30 having a fixed latency, but a steep amplitude gradient moving toward the scalp vertex. A P40 component followed, having longer peak latencies, moving the recording sites from contralateral medial parietal toward the vertex and frontal ipsilateral positions. MN-SEPs in contralateral parietal leads contained a widespread N20 with a maximum source posterior to the Cz-ear line. The following P25 enveloped two subcomponents - early and late P25 - having different distributions. The late P25 showed a maximum - coincident with that of wave N20 - which was localized more posteriorly than that of the early P25. An inconstant wave N33 with progressively longer peak latencies from sagittal toward lateral positions was then recorded. MN-SEPs in contralateral central positions showed a well-localized P22 wave in which both the parietal early P25 and the frontal P20 were vanishing. Common or separate generators for frontal, central and parietal SEPs were discriminated by evaluating the influence of stimulus rate and intensity, as well as of general anesthesia and transient CBF deficits, investigated in 7 patients undergoing carotid endarterectomy. Unifocal anodal threshold shocks were separately delivered to each of the scalp electrodes and motor action potentials were recorded from the target muscle in order to delineate the scalp representation of the motor strip for the upper limb and, consequently, to monitor, through SEP tracings, the short-latency sensory input to the motor cortex for hand and shoulder muscles. This was characterized by a boundary zone separating the parietal N20-early P25 complex, from the fronto-central N18-P22 one. This zone had an oblique direction strongly resembling that of the central sulcus.

Adult↗
PubMed1987

Monitoring of subcortical and cortical somatosensory evoked potentials during carotid endarterectomy: comparison with stump pressure levels.

Monitoring of multichannel somatosensory evoked potentials (SEPs) has been performed in 40 cases of carotid endarterectomy (CEA). SEPs were obtained after median nerve stimulation at wrist, recording from 2nd cervical and from the scalp parietal (ipsi- and contralateral) and central (contralateral) positions. The reduction of CBF due to clamping of the carotid artery provoked SEP abnormalities in 10 of the 40 cases. None of the 30 patients with unmodified SEPs developed post-surgical neurological sequelae. SEP alterations were characterized exclusively by amplitude decrements and latency increases of the cortical components, the subcortical ones being unaffected. In 5 of these patients, SEPs returned to normal values before the end of the intervention and no neurological deficit was observed on awakening. In the remaining 5 cases SEPs retained their abnormalities and patients developed post-surgery neurological sequelae (4 immediately, 1 the day after). SEP alterations affected parietal and central components to a similar extent; however, in a few cases cerebral blood flow deficits provoked by carotid clamping modified differently the central P22 and the parietal N20-P25 waves. Comparisons with stump (back) pressure in the carotid artery revealed a higher sensitivity of the SEP technique in detecting vascularization problems due to carotid clamping. The time course of the appearance of SEP abnormalities seems to discriminate alterations secondary to collateral revascularization from those determined by embolization.

Adult↗
PubMed1986

On the spinal pathways mediating scalp-SEPs to upper and lower limb nerve stimulation: case report and discussion.

Scalp-SEPs to peroneal nerve stimulation were abnormal in a patient with an intradural meningeoma which was compressing the antero-lateral quadrant of the 1st and, partly, the 2nd cervical myelomers. In contrast, spine and scalp-SEPs were symmetrically normal during the sural, median and ulnar nerve stimulation of either side. On surgery, it was observed that the tumor had left the dorsal columns (DCs) almost unaffected. It is argued, in agreement with the bulk of experimental evidence, that in humans the scalp-SEPs to lower mixed nerve stimulation are also mediated, at the rostral cord level, by fast-propagating tracts ascending outside the DCs.

Adult↗
PubMed1985

Nervous propagation along 'central' motor pathways in intact man: characteristics of motor responses to 'bifocal' and 'unifocal' spine and scalp non-invasive stimulation.

In 23 healthy adult volunteers motor action potentials (MAPs) were elicited in upper and lower limb muscles during stimulation of appropriate sites at spinal and scalp level, through skin electrodes. 'Bifocal' stimulation of scalp and spine motor tracts was performed with 2 plaques (3.5 cm2 each), delivering single pulses of 440-940 mA, less than 50 microseconds in duration, which elicited high voltage (up to 10 mV) MAPs in arm and leg muscles. 'Unifocal' stimulation of scalp was carried out through a cathode consisting in a belt or in a series of rectangular interconnected plaques secured around the head, 1-2 cm rostral to the nasion-inion plane, and in a circular anode placed on the appropriate scalp site. MAPs with similar amplitude-latency characteristics were recorded with both 'bifocal' and 'unifocal' stimulating methods. However, the 'unifocal' stimulation necessitated 5-10 times less current than the 'bifocal' one. The 'unifocal' device using the interconnected plaques (6-12 in number) provided the most tolerable stimuli with the lowest amount of current (60-106 mA, rectangular pulses of 100-150 microseconds). Conduction times and velocities of motor pathways in various 'central' and 'peripheral' districts were calculated. Voluntary contraction of target muscles remarkably enhanced MAP amplitudes during scalp, but not during spine stimulation. A nerve action potential was recorded from ulnar nerve during scalp stimulation. MAPs in hand muscles to scalp stimulation were obliterated by the simultaneous activation of the peripheral fibres innervating the target muscle, because of collision between ortho- and antidromically propagated motor impulses. Anodal stimuli showed liminal values significantly lower than the cathodal ones. Mapping studies have been carried out with 'unifocal' scalp stimulation by using different types of anode and of stimulus parameters.

Action Potentials↗
PubMed1981

Evaluation of blood toxicity in chronic uremia by an improved chromatographic method.

Biogel P2 gel chromatography of ultrafiltrate from chronic uremic patients leads to better resolution of the compounds present than so far reported in the literature. Reproducibility is good. Toxicity, evaluated by cell cultures, was detected in only one chromatographic fraction. Further purification of this fraction with HPLC on a RP18 column revealed two toxic fractions, to the better defined of which a polyol structure was ascribed.

Animals↗