Visually induced syncope: a nonepileptic manifestation of visual sensitivity?
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Child↗
Biomedical subjects
S Seri
Publications and source records attributed to S Seri.
Dynamic susceptibility contrast perfusion imaging of cerebral ischemia in nonhuman primates: comparison of Gd-DTPA and NMS60.
PURPOSE: To study a new gadolinium (Gd) contrast agent-NMS60-for MR perfusion-weighted imaging (PWI) of brain tissue. MATERIALS AND METHODS: NMS60 is a Gd3+ trimer with a molecular weight of 2158 Daltons, and a T2 relaxivity almost three times higher than that of Gd-DTPA. Middle cerebral artery (MCA) occlusion was induced in nine nonhuman primates. The animals were scanned acutely and for up to six follow-up time points. PWI peak, and time-to-peak maps were generated, and perfusion deficit volumes were measured from these maps. The values of peak, time-to-peak, and perfusion deficit volume were compared between NMS60 and GD-DTPA. RESULTS: These results demonstrate that there was no significant difference in our calculated perfusion parameters between the two contrast agents. CONCLUSION: The two agents were found to be equally effective for PWI for acute and chronic stroke in primates. Along with its previously demonstrated advantage for T1-enhanced imaging, the current results show that NMS60 is a viable contrast agent for use in stroke patients.
Animals↗
A comparison of CH3-DTPA-GD (NMS60) and GD-DTPA for evaluation of acute myocardial ischemia.
PURPOSE: Our objective was to evaluate the use of a new medium weight MRI contrast agent, NMS60 (a synthetic oligomeric Gd-complex containing three Gd(3+) atoms, molecular weight 2158 Da) compared to gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) in a pig myocardial ischemia model. MATERIALS: We used 13 male white hybrid pigs. Animals were scanned in the acute phase 2-3 h after the onset of myocardial ischemia. Scans were acquired on a 1.5T GE Signa with dynamic T1-weighted imaging during a bolus injection of 0.1 mmol(gd)/kg of either NMS60 or Gd-DTPA, 2D CINE at 5 min after injection, and T1-weighted spin-echo imaging up to 60 min. RESULTS: The postcontrast CINE scans showed improved contrast-to-noise ratio after NMS60 injection, compared to Gd-DTPA. There was significantly greater enhancement with NMS60 in both normal myocardium and in the ischemic lesion on T1-weighted spin-echo scans up to 60 min after injection. The dose ranging study shows a 24% greater enhancement with NMS60 compared to Gd-DTPA. DISCUSSION: This new medium weighted contrast agent offers improved enhancement for cardiac MRI, compared to Gd-DTPA, with similar washout kinetics and lower toxicity, and may prove useful for better detection of myocardial ischemia as well as delayed or hyperenhancement after reperfusion.
Acute Disease↗
Early-onset encephalopathy and cortical myoclonus in a boy with MECP2 gene mutation.
The authors report the unusual clinical and neurophysiologic features of a sporadic case of a boy carrying an 806delG mutation on the MECP2 gene. A 28-month-old boy was examined for severe developmental delay, seizures, microcephaly, breathing dysfunction, and spontaneous and evoked myoclonic jerks of upper limbs. Neurophysiologic study proved the cortical origin of myoclonus; however, it was not associated with signs of cortical hyperexcitability. 3-Methoxy-4-hydroxy-phenylethylene glycol and valine concentrations were low in CSF.
Chromosomal Proteins, Non-Histone↗
A comparative evaluation of CH3-DTPA-Gd (NMS60) for contrast-enhanced magnetic resonance angiography.
In a canine model the signal dynamics of a new oligomer-based MR contrast agent (NMS60, 2158 Da) were compared to Gd-DTPA to investigate the agents' potential for magnetic resonance angiography (MRA). Twelve male mongrel dogs were imaged sequentially under anesthesia with two different MRA sequences (Tlw 3DSPGR). Initial enhancement was measured every 9 s for eight points in time. Thereafter, spatial highly resolved MRAs were obtained at 5, 10, 15, 20, 30, 45, and 60 min post-injection of two different dosages. Over the first 20 s following bolus administration the average arterial enhancement of 0.1 mmol(Gd)kg NMS60 was 44% greater than Gd-DTPA. Twenty minutes post-injection the relative signal intensity of NMS60 was as high as the peak signal intensity with Gd-DTPA at the same dosage level (0.1 mmol(Gd)/kg). In the animals that received NMS60 injections the vascular conspicuity was overly superior to those who received Gd-DTPA. No significant toxicity effects were noted for either dosage level. The intermediate weight contrast agent NMS60 offers greater vascular enhancement and retention time than Gd-DTPA. For a given set of optimized imaging parameters this offers improved spatial details, less arterial/venous overlap, and better vascular contrast.
Animals↗
The effect of intrathecal baclofen on muscle co-contraction in children with spasticity of cerebral origin.
AIM: Investigation of the effect of intrathecal baclofen administration on the time course of electrical patterns of muscle activation in patients with spasticity due to upper motor neuron syndrome. METHODS: Six children with clinical signs of upper motor neuron syndrome resulting from an acquired cerebral hypoxic injury were tested. Simultaneous multichannel acquisition of surface EMG activity from flexor/extensor muscle groups of the upper and lower limbs was recorded. Investigated muscle group pairs included biceps/triceps brachii, wrist flexors/extensors, rectus/biceps femoris and tibialis anterioris/gastrocnemius. Time-frequency analysis of EMG activity at rest and while eliciting a stretch reflex was performed. The non-linear cross-correlation coefficient and time lag estimation were computed between paired channel groups both for baseline and post-intrathecal baclofen injection conditions for epochs consisting of 2 s prior to and 2 s after voluntary contraction. The effect of baclofen was assessed 3 h following single-bolus intrathecal injections of 25 or 50 microg during the baclofen trial and 6 months after baclofen pump implantation. RESULTS: In the baseline condition, the stretch reflex resulted in a synchronous increase in spectral EMG power in both the agonist and the antagonist muscles. The mean correlation coefficient between agonist and antagonist muscles was 0.948 (SD = 0.034), and the mean time lag was 4.64 ms (SD = 1.84 ms). After intrathecal administration of baclofen, a dramatic decrease in the correlation coefficient between agonist and antagonists (mean value = 0.342) during voluntary contraction was observed. This corresponded to a significant reduction of tone and spasticity in all four limbs, and reduction of the Ashworth score by 2 points on average. CONCLUSION: After intrathecal baclofen administration, we observed a significant decrease in the co-contraction pattern typically associated with upper motor neuron spasticity. This was evident clinically and was quantitatively expressed by the significantly decreased degree of coupling in EMG activity of agonist/antagonist muscles. Although a relatively small sample was investigated in this study, we were able to demonstrate the efficacy of this procedure in restoring selective activation of agonists during voluntary contraction. This is one of the prerequisites of an improvement of motor function in patients with spasticity.
Adolescent↗
The clinical value of electroencephalogram/magnetic resonance imaging co-registration and three-dimensional reconstruction in the surgical treatment of epileptogenic lesions.
With the rapid developments in image processing, new clinical applications of manipulation and three-dimensional (3-D) reconstruction of neuro-imaging are evolving. Combination with other non-invasive techniques aimed at localising electric sources in the brain is of particular interest. These techniques rely on the recording of brain electrical activity and/or the associated magnetic fields from multiple areas on the scalp. Data obtained from an electroencephalogram (EEG) or from magnetoencephalography (MEG) can be fused in 3-D arrangement with anatomical [magnetic resonance imaging/computerised tomography (MRI/CT)] and/or metabolic [positron emission tomography (PET)] data. Such techniques highlight information on the functional correlates of anatomical or space-occupying lesions and their role in the localisation of related symptomatic epilepsy. In the present study we report on methodological issues and preliminary clinical data on spectral EEG/MRI co-registration procedures, offering two examples of children presenting with hemispheric lesions, one frontal tumour and one temporal arterio-venous malformation. The EEG was acquired from 32/64 electrode location. The electrode position and that of four reference points were measured with a dual sensor Polhemus 3D Isotrak digitiser. Sources of EEG activity were determined in 3-D space with the inverse solution method low resolution electromagnetic tomography (LORETA), providing for each frequency component, the topographic distribution of active electrical sources. The positions of the reference points were also measured on MRI, and co-registration of EEG and MRI was achieved using a transformation algorithm. The reconstructed 3-D images of co-registered EEG/MRI clearly demonstrate the relationship between the space-occupying lesion and the epileptic activity. Preliminary results show that in all the patients it was possible to identify with a remarkable accuracy the 3-D topographic relationship between lesion and cortical areas showing localised abnormalities on the EEG. The present method could further enhance the understanding of the effect of resective treatment of structural lesions on brain functioning. The new combined images can be used in combination with image-guided surgery equipment to modify effective surgical resection.
Brain↗
Infantile spasms in tuberous sclerosis complex.
The high incidence of infantile spasms (IS) and hypsarrhythmia in tuberous sclerosis complex (TSC) has long been emphasized but it is now clear that infants with TSC show clinical and EEG differences from those with classical West syndrome. Seizures at onset are mainly characterized by partial motor seizures and IS. Subtle partial seizures may be present in the early neonatal period and may precede the onset of IS. Visual recording techniques have led to significant progress in the classification of seizures associated with TSC, demonstrating that they have a focal or multifocal origin in the vast majority of cases. In most cases, an awake interictal EEG shows focal or independent multifocal spike and slow-wave activity at onset and later a pseudo-hypsarrhythmic pattern. Ictal EEG starts with focal spikes originating from the posterotemporal, or occipital regions followed by a generalized irregular slow transient and an abrupt diffuse flattening. Although the pathophysiological mechanisms responsible for the coexistence of partial seizures and IS are still unclear, IS associated with TSC may be the result of a rapid secondary generalization. The presence of IS due to TSC is strongly predicted by the cortical tuber count, while the age of onset of seizures and the age of occurrence of EEG foci depend on the localization of cortical tubers with an earlier expression of the parieto-occipital than of the frontal regions. Early recognition of these distinctive features appears worthwhile for therapeutic and prognostic implications. Despite the efficacy of vigabatrin the prognosis of IS is generally poor. Studies using combined topographic mapping of EEG, magnetic resonance imaging and positron emission tomography may provide new strategies for selecting candidates suitable for surgery.
Electroencephalography↗
Melatonin as a sleep inductor for electroencephalogram recordings in children.
OBJECTIVE: To determine the efficacy of melatonin in obtaining sleep electroencephalograms in children. METHODS: Melatonin was used in 68 unselected children referred to the neurophysiology department for sleep electroencephalogram (EEG). A group of 68 children matched for age and sex who underwent EEGs after sleep deprivation in the same period was used as control. Sleep latency, as well as latency from stage 1 to stages 2, 3 and 4 were measured. RESULTS: No difference in the number of children who went to sleep was seen. No significant difference is the macrostructure of sleep was seen, other than a reduced sleep latency for the melatonin group (P<0.01). CONCLUSION: The study suggests that melatonin can reliably be used for obtaining sleep EEGs in children. Its use seems to provide a good alternative to pharmacological sedation and a complementary method to sleep deprivation.
Child↗
Idiopathic central pontine myelinolysis in childhood.
Central pontine myelinolysis (CPM) is rare in childhood with only a few cases reported in world literature. We report a 7-year-old male who presented with acute ataxia, swallowing difficulties, dysarthria, and radiological features consistent with the disorder. He improved remarkably with oral prednisolone therapy and was almost back to normal by 2 weeks. A review of the literature is also included.
Anti-Inflammatory Agents↗
Melatonin is useful for recording sleep EEGs: a prospective audit of outcome.
The study aimed to determine if melatonin could reliably induce sleep in children undergoing sleep EEG without affecting the usefulness of the EEG itself. One hundred and sixty three children (112 males, 51 females; mean age 8 years, range 1 to 16 years) referred for sleep EEG were studied. The children were given 2 to 10 mg of melatonin, depending on age, just before EEG recording. Measurements included sleep-onset latency, adverse effects, and acceptability of the EEG. Usefulness and acceptability of melatonin-induced sleep EEG were compared with the standard technique of sleep EEG following sleep deprivation in 30 children (matched for sex and age). Sleep was obtained in 79% of the 163 children who received melatonin after an average of 33 minutes. Yield of epileptiform abnormalities demonstrated in the melatonin sleep EEG was similar to that reported in the literature for sleep-deprived EEGs. There was no significant adverse effect. When compared, a melatonin-induced sleep EEG was as useful as a sleep-deprived EEG. However, the children's behaviour on the day of the melatonin-induced sleep EEG recording was more acceptable to parents.
Antioxidants↗
Melatonin as a sedation substitute for diagnostic procedures: MRI and EEG.
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Anticonvulsants↗
Derangement of the dopaminergic system in phenylketonuria: study of the event-related potential (P300).
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Adolescent↗
Dynamic contrast-enhanced MRI of Implanted VX2 tumors in rabbit muscle: comparison of Gd-DTPA and NMS60.
We studied the dynamics of injected contrast enhancement in implanted VX2 tumors in rabbit thigh muscle. We compared two contrast agents Gd-DTPA and NMS60, a novel gadolinium containing trimer of molecular weight 2.1 kd. T1-weighted spin echo images were acquired preinjection and at 5-60 min after i.v. injection of 0.1 mmol/kg of agent. Dynamic T1-weighted SPGR images (1.9 s/image) were acquired during the bolus injection. Male NZW rabbits (n = 13) were implanted with approximately 2 x 10(6) VX2 tumor cells and grew tumors of 28+/-27 mL over 12 to 21 days. NMS60 showed significantly greater peak enhancement in muscle, tumor rim, and core compared to DTPA in both T1-weighted and SPGR images. NMS60 also showed delayed peak enhancement in the dynamic scans (compared to Gd-DTPA) and significantly reduced leakage rate constant into the extravascular space for tumor rim (K21 = 5.1 min(-1) vs. 11.5 min(-1) based on a 2 compartment kinetic model). The intermediate weight contrast agent NMS60 offers greater tumor enhancement than Gd-DTPA and may offer improved regional differentiation on the basis of vascular permeability in tumors.
Animals↗
Autism in tuberous sclerosis: evoked potential evidence for a deficit in auditory sensory processing.
OBJECTIVE: Autism is a frequent manifestation of tuberous sclerosis complex (TSC) being reported in up to 60% of the patients. Its presence is in association with cortical and subcortical lesions involving the temporal lobes. This study was designed to shed light on the functional mechanisms linking anatomical lesions of TSC and behavioural phenotype by investigating scalp recorded event related potentials to auditory stimuli. METHODS: Fourteen children with TSC, seven of which fulfilled the DSM IV criteria for autistic disorder were selected for this study. All of the subjects underwent high resolution MRI, EEG, brainstem auditory evoked potentials, cognitive and behavioural evaluation. Electrical evoked responses to two different pitches, presented with different probability (80% 1000 Hz, 20% 1500 Hz) were recorded from 21 scalp electrodes in the autistic and non-autistic subgroups, to assess central auditory processing and automatic memory. RESULTS: The first component of the long latency auditory response (N1) had a significantly prolonged latency with lower amplitude in all of the patients with autistic behaviour who, contrary to non-autistics had MRI lesions involving one or both temporal lobes. A mismatch negativity was detected in all subjects and had a longer latency in subjects with autistic behaviour. CONCLUSIONS: To our knowledge this is the first electrophysiological evidence of a deficit in auditory information processing and automatic memory in TSC patients with autistic behaviour.
Auditory Perception↗
The acceptability of sleep-deprived electroencephalograms.
The aim of this study was to ascertain the acceptability of sleep-deprived EEGs to parents and their young child. Fifty unselected children having a sleep-deprived EEG were recruited. Data were collected from a sleep diary, a parent questionnaire and the request form of the EEG. Data collected covered developmental, learning and behavioural problems and the acceptability of the sleep-deprived EEG. There were 29 males (58%) in the study group. The average age was 8.6 years (range 2-17 years). Fifty percent of parents found it difficult to keep their child awake at night and 30% of parents found it difficult to wake their child in the morning. Fifty-four percent of parents reported their child had difficult behaviour on the day of the EEG. None had seizures provoked by sleep deprivation.
Adolescent↗
Landau-Kleffner syndrome and atypical benign partial epilepsy of childhood: the effectiveness of acetazolamide.
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Acetazolamide↗
Spike-induced interference in auditory sensory processing in Landau-Kleffner syndrome.
OBJECTIVES: Landau-Kleffner Syndrome (LKS) is an epileptic syndrome characterised by a deficit in language comprehension and production, paroxysmal epileptiform activity in the posterior temporal leads, and by the inconsistent presence of epileptic fits. Its interest lies in the fact that it stands as a model for the study of interference of epileptiform activity on cognitive function, although the pathophysiology of the decline in language skills that follows its onset has not yet been clarified. METHODS: We have recorded spike-triggered auditory evoked responses in a group of 6 children with LKS, to investigate whether the occurrence of individual EEG paroxysms is able per se to induce a decline in the response of the auditory cortex. RESULTS: Results have indicated that left hemisphere spikes are associated with a greater reduction in amplitude and an increase in latency of the NI, than spikes occurring in the right hemisphere. No stable change in the evoked response has been detected outside of the EEG paroxysm. CONCLUSIONS: We postulate EEG interictal activity is able to induce impairment in processing auditory information and that this may play a role in the pathogenesis of language deficit in LKS.
Auditory Cortex↗