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Biomedical subjects

M Valeriani

Publications and source records attributed to M Valeriani.

At least 73 records · Page 4Linked to original sources
PubMed1997

Giant central N20-P22 with normal area 3b N20-P20: an argument in favour of an area 3a generator of early median nerve cortical SEPs?

Generators of early cortical somatosensory evoked potentials (SEPs) still remain to be precisely localised. This gap in knowledge has often resulted in unclear and contrasting SEPs localisation in patients with focal hemispheric lesions. We recorded SEPs to median nerve stimulation in a patient with right frontal astrocytoma, using a 19-channel recording technique. After stimulation of the left median nerve, N20 amplitude was normal when recorded by the parietal electrode contralateral to the stimulation, while it was abnormally enhanced in traces obtained by the contralateral central electrode. The amplitude of the frontal P20 response was within normal limits. This finding suggests that two dipolar sources, tangential and radial to the scalp surface, respectively, contribute concomitantly to N20 generation. The possible location of the N20 radial source in area 3a is discussed. The P22 potential was also recorded with increased amplitude by the central electrode contralateral to the stimulation, while N30 amplitude was normal in frontal and central traces. We propose that the radial dipolar source of P22 response is independent from both N20 and N30 generators and can be located either in 3a or in area 4. This report illustrates the usefulness of multichannel recordings in diagnosing dysfunction of the sensorimotor cortex in focal cortical lesions.

Adult↗
PubMed1997

The pathophysiology of giant SEPs in cortical myoclonus: a scalp topography and dipolar source modelling study.

Somatosensory evoked potential (SEP) recordings in patients suffering from cortical myoclonus (CM) are characterised by evidence of abnormally enhanced scalp components. Our aim was to verify whether enhanced activity in giant SEPs arises from the same generators as in healthy subjects. We used the brain electrical source analysis (BESA) to compare scalp SEP generators of healthy subjects to those calculated in 3 patients with CM of varying causes. Firstly, we built a 4-dipole model explaining scalp distribution of early SEPs in normal subjects and then applied it to traces recorded from CM patients. Our model, issued from the right median nerve grand average and applied also to recordings from single individuals, included a dipole at the base of the skull and three other perirolandic dipoles. The first of the latter dipoles was tangentially oriented and was active at the same latencies as the N20/P20 potentials and, with opposite polarity, the P24/ N24 responses; the second dipole explained the central P22 distribution and the third had a peak of activity corresponding to the N30 component. When we applied our 4-dipole model to CM recordings, the first perirolandic dipole had a third peak of activity in all patients at the same latency as a parietal negativity and a frontal positivity, both following giant P24/N24 components; on the other hand, in one patient the second perirolandic dipole showed a later activation corresponding to a high central negativity, following a giant P22 response. We suggest that only the initial giant SEPs correspond to physiological potentials evoked in healthy subjects. The occurrence of late giant SEPs could be explained by hyperpolarization, following the postsynaptic excitatory potentials responsible for the early giant components.

Adult↗
PubMed1997

Functional involvement of central nervous system in mitochondrial disorders.

Thirty-nine patients with mitochondrial diseases were studied with somatosensory and motor evoked potentials. Sixteen patients (41%) had clinical and 12 (31%) had neuroradiological evidence of central nervous system involvement. The overall incidence of electrophysiological abnormalities was 64%. Abnormal evoked potentials were also found in a significant percentage (33%) of patients with pure myopathic forms of mitochondrial diseases and in an asymptomatic carrier of MERRF mutation. Of the individual tests, somatosensory evoked potentials were abnormal in 49% of the patients and motor evoked potentials were abnormal in 46% of the patients. The outcome is that electrophysiological evidence of central nervous system involvement is present in a high percentage of patients with mitochondrial disorders, and that the threshold for central nervous system electrophysiological abnormalities is well below that for clinical and/or radiological manifestations.

Adolescent↗
PubMed1997

Neurophysiological abnormalities in adrenoleukodystrophy carriers. Evidence of different degrees of central nervous system involvement.

We studied 19 women, heterozygous for adrenoleukodystrophy (ALD) in whom the carrier status was demonstrated by abnormally high plasma levels of very-long-chain fatty acids. Clinical examination revealed slight neurological signs in two patients. Clear-cut neurological deficits in three, and it was fully normal in the remaining 14. All subjects underwent motor evoked potential (MEP) and somatosensory evoked potential (SEP) studies. Seventeen out of 19 subjects underwent brain MRI which demonstrated various degrees of abnormality in one asymptomatic and five symptomatic subjects; SEPs and MEPs revealed CNS involvement in 12 and 8 out of the 19 subjects, respectively. Symptomatic patients showed severe neurophysiological abnormalities, whereas milder but unequivocal EP abnormalities were found in seven of the 14 patients with normal clinical examination. Our data thus suggest CNS involvement in the majority of the ALD carriers, evident also in preclinical stages and progressively severe. The possibility of assessing different degrees of neurological involvement could be relevant for therapeutical purposes. Moreover, neurophysiological studies could provide the only objective marker of functional nervous system involvement, e.g. in order to monitor the efficacy of treatment, and in clinically and radiologically silent cases.

Adolescent↗
PubMed1997

Ischaemic myelopathy associated with cocaine: clinical, neurophysiological, and neuroradiological features.

Two patients with spinal infarction and one patient with the previously unreported complication of spinal transient ischaemic attack associated with cocaine misuse are reported. Spinal MRI documented an infarction in the territory of the anterior spinal artery in the first two patients and was completely normal in the patient with a transient ischaemic attack. Motor evoked potentials were abnormal in all three patients.

Adult↗
PubMed1996

Brain-stem somatosensory dysfunction in a case of long-standing left hemispherectomy with removal of the left thalamus: a nasopharyngeal and scalp SEP study.

We have studied median nerve somatosensory evoked potentials (SEPs) in a patient who had undergone early surgical removal of the left cerebral hemisphere and left thalamus. Stimulation of the right side evoked normal latency P9, P11 and P13 potentials at scalp as well as at nasopharyngeal (NP) leads, while P14 and N18 potentials were absent. These SEP abnormalities, that have been described previously in cervico-medullary lesions and in comatose patients with upper brain-stem involvement, suggest that in our patient the removal of the left thalamus has caused retrograde degeneration of the cuneate-thalamic projections. Moreover, this study confirms that P13 and P14 potentials have different generators.

Adolescent↗
PubMed1996

Central nervous system modifications in patients with lesion of the anterior cruciate ligament of the knee.

Patients with traumatic lesion of the anterior cruciate ligament often experience knee instability, which, recent studies suggest, is probably due to reduced knee proprioception. We studied knee proprioception and somatosensory evoked potentials (SEPs) after stimulation of the common peroneal nerve at the knee above the articular branches subserving the sensory innervation of the anterior cruciate ligament, in 19 patients with traumatic anterior cruciate ligament lesion. Ten patients showed decreased position sense of the knee, and of these, seven presented loss of cortical P27 potential while preserving lemniscal P20 and spinal N14 responses to common peroneal nerve stimulation on the side of the anterior cruciate ligament lesion. All our patients had normal SEPs to stimulation of the posterior tibial nerve at both the ankle and the knee. We suggest that in patients showing SEP abnormalities, the dysfunction of the central somatosensory conduction is located above the medial lemniscus and is limited to common peroneal nerve somatosensory pathways. Therefore, it is likely that in the seven patients showing SEP abnormalities, the loss of the knee mechanoreceptors was followed by remodelling of the CNS above the medial lemniscus. In five patients with P27 absence after common peroneal nerve stimulation, we also recorded SEPs after stimulation of the peroneal nerve at the ankle and obtained a normal cortical positive response; moreover, in our healthy subjects, cortical responses were significantly higher in amplitude after peroneal nerve than after common peroneal nerve stimulation. These findings strongly suggest that proprioceptive afferent inputs from the knee are more effective than distal afferent inputs in generating the greater part of the common peroneal nerve cortical SEPs. Since common peroneal nerve stimulation probably allows selective recording of the responses produced by the activation of the cortical representation of the knee, minor lesions with a reduction in the number of knee mechanoceptors could result in SEP changes after common peroneal nerve stimulation.

Adult↗
PubMed1996

Spinal responses to median and tibial nerve stimulation and magnetic resonance imaging in intramedullary cord lesions.

We recorded median and tibial nerve somatosensory evoked potentials (SEPs) in 18 patients with intramedullary lesions of the cord (intramedullary tumors in 14 patients and syringomyelia cavitations in 4). Patients were divided into four groups on the basis of the longitudinal extension of the lesions as revealed by magnetic resonance imaging. The lesions involved the cervical cord in nine patients (group 1), both cervical and lumbar cord ("holocord" lesion) in two (group 2), the dorsal cord in one (group 3), and the lumbar cord in six (group 4). The recording technique enabled us to analyze clearly the spinal SEPs, labeled for the median nerve as N13, and for the tibial nerve as N24. Both spinal responses are probably generated by the activation of dorsal horn cells and proved useful in revealing focal lesions of the cervical or lumbar cords. Median nerve N13 was abnormal in all group 1 and group 2 patients; in three patients, this was the only median SEP abnormality, suggesting that the dysfunction was limited to the cervical grey matter. Tibial nerve N24 was abnormal in all group 2 and group 4 patients. The abnormality of both cervical and lumbar segmental responses in patients with holocord lesions strongly suggested that both the cervical and lumbar cords were involved. The SEP study was often more effective than the clinical examination in revealing cord involvement and the actual extension of damage. The recording of the spinal SEPs is thus highly sensitive in assessing cord dysfunction in intramedullary lesions, providing that specific recording techniques are used.

Adult↗
PubMed1995

Origin and distribution of P13 and P14 far-field potentials after median nerve stimulation. Scalp, nasopharyngeal and neck recording in healthy subjects and in patients with cervical and cervico-medullary lesions.

We studied median nerve SEPs in 10 healthy subjects, by means of simultaneous recording over the scalp, around the neck and near the ventral surface of the medulla using a nasopharyngeal (NP) electrode. This recording technique enabled us to clearly differentiate P13 and P14 potentials. The former was always found in NP records, while the latter was more evident in scalp traces. The same technique was used to study 9 patients with various lesions of the cervical cord or cervico-medullary junction. Patients with high cervical lesions demonstrated abnormalities of both P13 and P14 potentials, while patients with lesions of the cervico-medullary junction demonstrated a clear dissociation between normal P13 in scalp and NP traces, and abnormal scalp P14. Patients with lower cervical lesions, selectively involving the central grey matter, showed normal P13 and P14 potentials, in spite of abnormal N13 cervical responses. Our findings strongly suggest that both scalp and NP P13 have the same generators in higher segments of the cervical cord, and that NP more than scalp records are effective in analyzing the P13 response. We suggest that the selective recording of the P13 potential could be useful in the assessment of focal lesions of the higher cervical cord or of the cervico-medullary junction.

Adult↗
PubMed1995

Recovery after surgery of the spinal N24 SEP in dural arteriovenous malformation of the dorsal cord.

We studied somatosensory evoked potentials (SEPs) to tibial nerve stimulation in two patients suffering from dorsal dural arteriovenous malformation (AVM). We found in both patients abnormalities in the lumbar N24 potential and in the cortical P40 response. After surgical removal of the AVM, the N24 recovered in both patients. Cord lesions probably occur in patients with dural AVM because of a theft of blood through the fistula; N24 recovery may therefore be associated with a restoration of blood supply after surgery. The N24 recovery in our patients with dural AVM suggests that the abnormality of this potential does not necessarily reflect irreversible damage to the lumbo-sacral cord and that the N24 recording can be useful in post-surgical monitoring.

Aged↗
PubMed1994

The role of upper limb somatosensory evoked potentials in the management of cervical spondylotic myelopathy: preliminary data.

We studied upper limb somatosensory evoked potentials (SEPs) in 11 patients with MRI and clinical evidence of cervical spondylotic myelopathy (CSM), before and after cervical open-door laminoplasty. SEP studies before surgery revealed two main types of abnormality, the first characterized by the isolated loss of the spinal N13 response, reflecting the dysfunction of dorsal horn cervical cells in 4 patients. The second combined abnormalities of both spinal N13 and scalp far-field P14 potential, suggesting the involvement of both dorsal horn cells and dorsal columns at the cervical level in 7 patients. After surgery, N13 recovered in 9 patients, while P14 abnormalities remained unchanged. Clinical recovery, evaluated by means of the Japanese Orthopaedic Association (JOA) disability scale, was accompanied by SEP improvement. Moreover, this improvement was more pronounced in patients with isolated loss of the N13 than in patients with combined abnormalities of the N13 and scalp P14 response. Our data strongly suggest that upper limb SEPs can be useful in monitoring the effectiveness of surgery, as well as in selecting before surgery patients who are likely to have a better postsurgical outcome.

Adult↗
PubMed1994

Somatosensory evoked potentials after multisegmental upper limb stimulation in diagnosis of cervical spondylotic myelopathy.

Radial, median, and ulnar nerve somatosensory evoked potentials (SEPs) were recorded, with non-cephalic reference montage, in 38 patients with clinical signs of cervical myelopathy and MRI evidence of spondylotic compression of the cervical cord. Upper limb SEPs are useful in spondylotic myelopathy because SEPs were abnormal in all patients for at least one of the stimulated nerves and SEP abnormalities were bilateral in all patients but one. Reduction of the amplitude of the N13 potential indicating a segmental dysfunction of the cervical cord was the most frequent abnormality; it occurred in 93.4%, 84.2%, and 64.5% of radial, median, and ulnar nerve SEPs respectively. A second finding was that the P14 far-field potential was more sensitive than the cortical N20 potential to slowing of conduction in the dorsal column fibres. The high percentage of N13 abnormalities in the radial and median rather than in the ulnar nerve SEPs correlated well with the radiological compression level, mainly involving the C5-C6 vertebral segments. Therefore the recording of the N13 response is a reliable diagnostic tool in patients with cervical spondylotic myelopathy and P14 abnormalities, though less frequent, can be useful in assessing subclinical dorsal column dysfunction.

Adult↗
PubMed1993

N24 spinal response to tibial nerve stimulation and magnetic resonance imaging in lesions of the lumbosacral spinal cord.

We studied tibial nerve somatosensory evoked potentials (SEPs) in 22 patients with progressive clinical signs of sensory and motor involvement of the lower limbs. Magnetic resonance imaging (MRI) in 21 patients revealed lesions of the thoracolumbar cord in 18 and of the cauda equina in the remaining three. SEP recordings enabled us to clearly differentiate the response generated by the dorsal horns of the lumbosacral cord from the activity generated in the cauda equina dorsal roots. Neurophysiologic findings strongly correlated with the lesion site demonstrated by the MRI (cauda equina, lumbosacral cord, or thoracic cord immediately above the lumbar enlargement). The N24 cord potential was absent with a normal cauda equina response in 10 of 12 patients with MRI signs of lumbosacral cord lesions. Clinical examination often failed to localize the spinal cord as the lesion site, suggesting pure peripheral involvement in six of the 12 patients with MRI signs of lumbosacral cord lesions.

Adult↗
PubMed1992

Segmental dysfunction of the cervical cord revealed by abnormalities of the spinal N13 potential in cervical spondylotic myelopathy.

We studied somatosensory potentials (SEPs) evoked by stimulation of radial, median, and ulnar nerves in 11 patients with MRI evidence of cervical spondylosis. All patients presented with progressive spastic paraparesis that was either isolated or associated with lower motor neuron signs in the upper limbs, with preserved joint, touch, pain, and temperature sensations in the four limbs. In all patients, scalp SEPs reflecting the activity of the dorsal column system up to the parietal cortex were normal while segmental cervical cord dysfunction was manifested by an abnormal spinal N13 potential in 95% of radial, 90% of median, and 54% of ulnar nerve SEPs. These subclinical abnormalities of the spinal N13 SEP probably result from reduced blood supply due to compression of the anterior spinal artery in patients with cervical spondylotic myelopathy.

Adult↗
PubMedDate not supplied

Brachytherapy for squamous cell carcinoma of the lip. The experience of the Institute of Radiology of the University of Rome "La Sapienza".

AIMS AND BACKGROUND: Cancer of the lip is the most common malignancy occurring in the oral cavity. The aim of our retrospective study was to review the results of patients with lower lip squamous cell carcinoma who were treated with radiotherapy. METHODS & STUDY DESIGN: From 1970 to 1992, 57 patients with squamous cell carcinoma of the lower lip were treated at the Institute of Radiology of the University of Rome "La Sapienza" with low-dose rate interstitial brachytherapy. According to the UICC 1992 TNM classification, the disease stage was T1 in 27 (47%) cases, T2 in 20 (35%) and T3 in 10 (18%); 8 patients (14%) were cN+. The median tumor dose was 62 Gy (range, 44-96): 10 patients (18%) received a total dose < 50 Gy, 28 (49%) between 50 and 70 Gy, and 19 (33%) > 70 Gy. The cN+ cases were irradiated to total doses of 65-70 Gy on the involved station. All patients obtained complete remission. RESULTS: The actuarial overall survival rates at 3, 5 and 10 years were 95%, 76% and 53%; actuarial disease-free survival at 3, 5 and 10 years was 84%, 81%, and 81%, respectively. Actuarial cause-specific survival was 98%, 88% and 84% at 3, 5 and 10 years, respectively. Actuarial local control rate was 90% at 3 and 5 years, rising to 94% with salvage surgery. Local-regional control was obtained in 90% and 86% of patients at 3 and 5 years, and in 93% and 89% of cases, respectively, following surgery. Five of 11 deaths were due to local-regional or distant disease recurrence. CONCLUSIONS: Tumor stage and positivity of regional nodes were the only predictive factors of survival and disease control. Radiation-induced morbidity was very low, and all patients considered their cosmetic outcome at least satisfactory.

Aged↗
PubMedDate not supplied

Radiotherapy in classic Kaposi's sarcoma (CKS): experience of the Institute of Radiology of University "La Sapienza" of Rome.

Between 1992 and 1995 24 histologically demon strated Kaposi's. Sarcoma in 14 HIV negative patients were treated at the Institute of Radiology of the University "La Sapienza" of Rome. All patients underwent irradiation with 60CO in three different fractionations: 800 cGy in 1 fraction in 2 (8%) cases, 2000 cGy in 5 fractions in 18 (75%) and 300 cGy in 10 fractions in 4 (17%). Complete response was obtained in 13/24 (54%), partial response in 9/24 (38%), no change in 2/24 (8%). In 2 cases there were out field relapses 2 and 3 months after the end of therapy, and one patient presented with a field recurrence at 4 months. The median duration of local control was 19.5 months (range 4-40 months). All patients had complete remission of symptoms. Our results seem to confirm the effectiveness of radiotherapy in the local control and palliation of symptoms of CKS.

Aged↗
PubMedDate not supplied

Radiotherapy alone in elderly patients with medically inoperable stage IIIA and IIIB non-small cell lung cancer.

BACKGROUND: We have analysed our experience with medically inoperable IIIA and IIIB elderly patients (aged > or = 70 years), treated with radiotherapy alone, to better define the potential benefit of this approach. MATERIALS AND METHODS: From 1992 to 1995, 41 patients with NSCLC (Non Small Cell Lunc Cancer), stage III, aged > or = 70 years were irradiated with curative intent. RESULTS: Median follow-up was 20 months (range 9-53). The 2 year OS (Overall Survival) and DFS (Disease Free Survival) were respectively 27% and 14.6% for all patients. Patients presenting weight loss > 10% experienced 14% OS at 24 months compared to 58% for those without weight loss (p = 0.0027). A 64% OS at 24 months was seen in patients with tumor size less than 4 cm compared to 7% of patients with tumor size > 4 cm (p = 0.0009). CONCLUSION: Radiotherapy is a good management for locally advanced NSCLC in the elderly patients assuring good quality of life, high rates of relief of symptoms and OS and DFS similar to those obtained with chemotherapy and chemotherapy plus radiotherapy.

Aged↗