Biomedical subjects

Stefano Seri

Publications and source records attributed to Stefano Seri.

11 recordsLinked to original sources

PubMed2006

Pre-attentive auditory sensory processing in autistic spectrum disorder. Are electromagnetic measurements telling us a coherent story?

Sensory processing is a crucial underpinning of the development of social cognition, a function which is compromised in variable degree in patients with pervasive developmental disorders (PDD). In this manuscript, we review some of the most recent and relevant contributions, which have looked at auditory sensory processing derangement in PDD. The variability in the clinical characteristics of the samples studied so far, in terms of severity of the associated cognitive deficits and associated limited compliance, underlying aetiology and demographic features makes a univocal interpretation arduous. We hypothesise that, in patients with severe mental deficits, the presence of impaired auditory sensory memory as expressed by the mismatch negativity could be a non-specific indicator of more diffuse cortical deficits rather than causally related to the clinical symptomatology. More consistent findings seem to emerge from studies on less severely impaired patients, in whom increased pitch perception has been interpreted as an indicator of increased local processing, probably as compensatory mechanism for the lack of global processing (central coherence). This latter hypothesis seems extremely attractive and future trials in larger cohorts of patients, possibly standardising the characteristics of the stimuli are a much-needed development. Finally, specificity of the role of the auditory derangement as opposed to other sensory channels needs to be assessed more systematically using multimodal stimuli in the same patient group.

Attention↗

PubMed2006

Hypohidrosis during topiramate treatment: a rare and reversible side effect.

Topiramate is an antiepileptic drug with a beneficial clinical effect on various seizure types. Topiramate does not seem to be associated with serious adverse effects and is also well tolerated in pediatric patients. Only few cases of hypohidrosis have been described. This report presents one young patient with complex partial seizures who was medicated with topiramate when she developed fatigue, headache, intermittent hyperthermia, inability to produce sweat secretion, and dryness of the skin. Reduced sweat response was determined using the Wescor Macroduct collection procedure. Topiramate was discontinued, and within 3 weeks a repeat sweat test was completely normal. At that time, clinical signs had also disappeared. Hypohidrosis is an uncommon and reversible side effect reported in association with topiramate therapy. It is rare in patients on monotherapy. Although a definite causal relationship still needs to be established, this side effect might be attributed to an autonomic dysfunction by inhibition of isoenzymes of carbonic anhydrase localized in human eccrine sweat glands.

Anticonvulsants↗

PubMed2006

Deletion of the long arm of chromosome 6: report on a new case with intractable epilepsy.

Interstitial deletions in the terminal region of chromosome 6 are rare. The deletion most often occurs de novo. Mental retardation is always described. The most characteristic manifestations are microcephaly, micrognathia, hypotonia, typical facial appearance, strabismus, and congenital heart defects. Although this chromosomal syndrome does not appear to have a distinctive phenotype, epileptic seizures are uncommon in affected individuals. We report on a novel finding in a patient with the 46 XX karyotype and del(6)(q25-q26) who developed intractable epilepsy.

Abnormalities, Multiple↗

PubMed2005

Intractable seizures in tuberous sclerosis complex: from molecular pathogenesis to the rationale for treatment.

Tuberous sclerosis complex is a multisystem autosomal dominant genetic disorder resulting from mutations in one of two genes, TSC1 and TSC2. Pathologically, tuberous sclerosis complex is characterized by abnormal cellular differentiation and proliferation, as well as abnormal neuronal migration. Epilepsy occurs in about 90% of patients, with onset frequently in the first year of life. In a sizable proportion of individuals, seizures tend to be refractory to antiepileptic drug treatment. This article reviews the progress in understanding drug-resistant seizures in tuberous sclerosis complex, from molecular pathogenesis to the pathophysiologic mechanisms of epileptogenesis, and the rationale for appropriate medical and surgical treatment.

Brain↗

PubMed2004

Lamotrigine-induced seizure aggravation and negative myoclonus in idiopathic rolandic epilepsy.

The authors describe a paradoxical reaction to lamotrigine (LTG) treatment in a patient with idiopathic rolandic epilepsy characterized by seizure deterioration, the appearance of new seizure type, and transient cognitive impairment. This phenomenon was present at a low dose after a slow titration and promptly reverted on LTG discontinuation. This rare event may have similarities with carbamazepine-induced seizure worsening caused by the Na++ channel inhibitory effect of the two antiepileptic drugs.

Anticonvulsants↗

PubMed2004

Autism in tuberous sclerosis.

Despite considerable progress in the last few years, the neurobiologic basis of autism in tuberous sclerosis complex is still largely unknown and its clinical management represents a major challenge for child neurologists. Recent evidence suggests that early-onset refractory epilepsy and functional deficits associated with the anatomical lesions in the temporal lobes may be associated with autism. No one factor alone (cognitive impairment, tuber localization, occurrence of infantile spasms, focal EEG abnormalities), can be causally linked with the abnormal behaviour. Autism may also reflect a direct effect of the abnormal genetic program. Incidence of autism associated with Tuberous Sclerosis may be significantly higher than the rates of cardiac and renal abnormalities, for which screening is routinely conducted in this population. Hopefully, early diagnosis of autism will allow for earlier treatment and the potential for better outcome for children with Tuberous Sclerosis.

Autistic Disorder↗

PubMed2004

Epilepsy surgery for tuberous sclerosis.

Tuberous sclerosis complex is often associated with medically refractory epilepsy secondary to cortical tubers. Previous studies have identified an association between early seizure onset, greater seizure burden, and mental retardation in childhood. Early effective seizure control could therefore significantly reduce the adverse developmental effects of chronic epilepsy in tuberous sclerosis complex. In medically intractable epileptic patients, surgical treatment has been demonstrated to reduce or abolish seizures and the associated burden for the child and its environment. Epilepsy surgery has not been widely used in patients with tuberous sclerosis complex thus far, mostly because of the concern that the multifocal nature of the cortical lesions could be associated with the development of independent epileptogenic zones. Advances in electroencephalographic techniques, functional neuroimaging, and invasive cortical mapping are changing this view and allowing an increased number of tuberous sclerosis complex patients to be evaluated for resective surgery. Additional techniques emerging in the neurosurgical field may add further treatment options to the current state of the art.

Anticonvulsants↗

PubMed2004

Electrophysiological characterization of spontaneous and carbamazepine-induced epileptic negative myoclonus in benign childhood epilepsy with centro-temporal spikes.

OBJECTIVE: Epileptic negative myoclonus (ENM), a transient muscular atonic phenomenon time-locked to epileptiform EEG abnormalities, is often observed in children with benign childhood epilepsy with centro-temporal spikes (BECTS). In some, for unknown reasons, ENM can be worsened by carbamazepine (CBZ). We describe two children aged 11 and 15 years, in whom CBZ precipitated seizure worsening and ENM. We investigated the morphological and topographic features of the EEG abnormalities while on CBZ and after CBZ withdrawal and compared them with those from 9 children with classical BECTS. The aim of the study was to identify possible electrophysiological specificities in patients who eventually develop ENM during CBZ treatment. METHODS: The characterization of EEG abnormalities, related (R) and unrelated to ENM (U), in patients with ENM and rolandic discharges (RD) and in matched controls with BECTS was performed based on polygraphic digital EEG recordings. Off-line time-domain analysis included correlation coefficient between EEG and EMG channels, quantitative analysis on ENM, and topographic analysis on spike-and-wave complexes. Z-score test and paired t test were used when appropriate for statistical analysis on R, U and RD. RESULTS: Recordings in both children with BECTS and ENM while on CBZ showed frequent R discharges (mean interval between R=19.89+/-9.4 s in patient 1; 2.16+/-1.2 s in patient 2). Withdrawal of CBZ produced abatement of R (no R recorded in patient 1; 5.69+/-7.1 s in patient 2) and reduction of the slow wave component of R (P<0.01). Morphology and topography of R and RD differed in field distribution, amplitude (P<0.01) and duration (P<0.01) of the slow wave component. RD and U did not show a significantly different morphology and field distribution. CONCLUSIONS: Our findings suggest that an increased cortical inhibition could be the electrophysiological correlate of CBZ-induced ENM. If confirmed on a larger series, the presence of spike-wave (rather than sharp waves) discharges in children with BECTS might be used as an electrophysiological predictor of an abnormal response to CBZ.

Adolescent↗

PubMed2004

EEG diagnostic procedures and special investigations in the assessment of photosensitivity.

Photosensitivity can be assessed in laboratory conditions with different methods. The most common procedure is intermittent photic stimulation (IPS), whose effectiveness in detecting photosensitivity depends largely on methodologic aspects. Although IPS is a widespread and routinely used procedure in EEG laboratories, only recently has a standardization of the IPS method been proposed. Furthermore, other modalities of visual stimulation, including pattern stimulation and low-luminance visual stimulation (LLVS), have proven their usefulness in detecting photosensitivity. We provide an overview of the methodologic aspects and clinical implications of these procedures, resulting from recent consensus meetings, and the diagnostic usefulness of the LLVS technique in photosensitive individuals whose seizures are triggered particularly by television images. Finally, we briefly illustrate the potential of advanced neurophysiological (magnetoencephalography and high-density EEG) and functional imaging techniques in the investigation of the pathophysiologic mechanisms underlying photosensitivity.

Electroencephalography↗

PubMed2003

Auditory sensory processing in autism: a magnetoencephalographic study.

BACKGROUND: Patients with autism show clinical features suggestive of abnormal processing of auditory and other sensory information. We hypothesized that low-functioning autistic subjects present abnormalities in discriminating simple auditory stimuli at sensory system preconscious stages of cortical processing. METHODS: To verify our hypothesis, we used magnetoencephalographic measurements of mismatch field (MMF), which reflects the detection of a change in the physical characteristics of a repetitive sound. Fourteen patients (aged 8-32 years) who met DSM-IV diagnostic criteria for autistic disorder participated in an auditory oddball experiment. Ten healthy participants matched for age and gender acted as control subjects. RESULTS: Significant differences in cerebral responses between patients and control subjects were recorded. Whereas control subjects showed a clearly identifiable MMF, with distinct generators in the M100 brain wave with regard to latency, position, and strength, no identifiable MMF was present in the autistic group. CONCLUSIONS: Our findings suggest that low-functioning autistic subjects present a dysfunction at preconscious stages of cortical auditory discrimination, playing a role in the abnormal processing of auditory sensory afferences. The attention independence of the MMF allows for exclusion of an effect related to impaired attention or task-related responses.

Acoustic Stimulation↗

PubMed2003

Short-term nonhormonal and nonsteroid treatment in West syndrome.

PURPOSE: West syndrome (WS) is considered an age-dependent epileptic encephalopathy and also a particular type of electrical epileptic status. Short-term hormonal or steroid treatment of WS with good efficacy is reported in the literature. The aim of this retrospective multiinstitutional study was to evaluate the early discontinuation of nonhormonal and nonsteroid treatment for WS. METHODS: Twenty-two WS cases in which treatment was discontinued after a maximum of 6 months, were collected. Inclusion criteria were the presence of typical EEG hypsarrhythmia (HY) and video-EEG recorded epileptic spasms. Exclusion criteria were the presence of partial seizures or other seizure types before spasm onset. The patients were treated with vigabatrin (VGB) in 19 cases and nitrazepam (NTZ) in three. The dose range was 70-130 mg/kg/day for VGB and 0.7-1.5 mg/kg/day for NTZ. The drug was discontinued if spasms stopped and HY disappeared after a mean treatment period of 5.1 months (range, 3-6 months). All patients underwent repeated and prolonged awake and sleep video-EEG, both before and after drug discontinuation. RESULTS: Cryptogenic (15) and symptomatic (seven) WS patients were included. All the symptomatic cases had neonatal hypoxic-ischemic encephalopathy. The mean age at spasm onset was 5.5 months (range, 3-7 months; median, 6). The interval between spasm onset and drug administration ranged from 7 to 90 days (mean, 23 days; median, 20). The interval between drug administration and spasm disappearance ranged from 2 to 11 days (mean, 6 days; median, 6 days). The interval between drug administration and HY disappearance ranged from 3 to 30 days (mean, 9 days; median, 10 days). Drugs were stopped progressively over a 30- to 60-day period. Follow-up ranged from 13 to 50 months (mean, 26 months; median, 22 months). None of our cases showed spasm recurrence. CONCLUSIONS: Our data show that successful nonhormonal and nonsteroid treatment can be shortened to a few months without spasm recurrence in patients with cryptogenic or postanoxic WS.

Anticonvulsants↗