Bernard Dachy

Electrophysiology of spatial scene analysis: the mismatch negativity (MMN) is sensitive to the ventriloquism illusion.

OBJECTIVES The ventriloquism effect is the tendency to underestimate the spatial separation between synchronous auditory and visual signals moderately separated in space. If, as it is thought, this effect is pre-attentive, it could modulate the mismatch negativity (MMN) that indexes the automatic, pre-attentive detection of deviant auditory stimuli rarely occurring in a sequence of standard stimuli. We assessed the existence of an MMN evoked by auditory and visual signals made up of standard sounds coming from the same location as the visual signal and deviant sounds coming from lateral deviations (20 or 60 degrees). As first observed in a behavioral study, a ventriloquism effect occurred for 20 degrees spatial separation but not for 60 degrees. METHODS Cortical evoked potentials were recorded using the oddball paradigm on 8 adults in auditory alone and audiovisual conditions. RESULTS In the auditory alone condition, each spatial localization contrast elicited a significant MMN. In the audiovisual condition, a significant MMN was only evoked for the 60 degrees contrasts. CONCLUSIONS The MMN evoked by spatial separation contrasts (20 and 60 degrees) in the auditory alone condition was suppressed by the corresponding audiovisual condition only when the latter yielded a ventriloquism effect, suggesting that this effect occurs at an early perceptual level.

Electrophysiological assessment of the effect of intrathecal baclofen in spastic children.

OBJECTIVE To evaluate the effect of intrathecal baclofen in a group of dystonic children using electrophysiological procedures previously validated in spastic children. METHODS Seven children (aged 2-16 years) with dystonia of various aetiologies (dyskinetic cerebral palsy, pantothenate kinase-associated neurodegeneration and Aicardi-Goutières syndrome) underwent transcranial magnetic stimulation, H-reflex and flexor reflex studies before and after intrathecal injection of baclofen. The Barry-Albright Dystonia Scale (BADS) was used for clinical evaluation of dystonia. RESULTS Motor-evoked potentials, present in 2 of 5 patients before baclofen, were preserved after injection. Before baclofen, H reflex was present in 6 of 7 patients (mean H(max)/M(max:) 0.45+/-0.21). It was markedly reduced after the injection (mean H(max)/M(max:) 0.09+/-0.11) (P<0.001). Area of flexor reflex significantly decreased after baclofen (P=0.047), while threshold significantly increased (P=0.01). No significant clinical improvement of the BADS scores was observed (P=0.058). CONCLUSIONS These electrophysiological procedures, previously demonstrated to quantify the action of intrathecal baclofen in spastic adults and children, also appear sensitive in dystonic children. The electrophysiological changes are consistent with primarily spinal sites of action of baclofen. They appear more sensitive than clinical evaluation.

Predictive value of electrophysiology in children with hypoxic coma

Assessment of prognosis of children in hypoxic coma is difficult. The value of clinical evaluation is often limited. The usefulness of electrophysiologic tests has been documented mostly in adults and neonates and in cases of traumatic coma. We reviewed retrospectively 39 consecutive children with nontraumatic hypoxic coma to assess the prognostic value of EEG, visual, and auditory evoked potentials. Correlation between electrophysiology and neurologic outcome after mean follow-up period of 30 months was significant (r(s) = 0.6, P < 0.001). In contrast there was no correlation between Pediatric Risk of Mortality score (PRISM) and outcome (r(s) = -0.42, P = 0.8). Combining magnetic resonance imaging with electrophysiology further enhanced their prognostic value (r(s) = 0.69, P < 0.001). Neuroimaging was highly sensitive but less specific, and electrophysiologic tests were highly specific but less sensitive. We conclude that early electrophysiology can contribute to predicting outcome in pediatric hypoxic coma.

Benign intracranial hypertension : atypical presentation of Miller Fisher syndrome?

Acute ocular paresis, nausea, vomiting, and headaches associated with high intracranial pressure without obvious intracranial pathology are typical features of benign intracranial hypertension. We describe two young children whose presentation, initially suggestive of idiopathic or benign intracranial hypertension, evolved to comprise ophthalmoplegia, ataxia, and areflexia. This triad characterizes Miller Fisher syndrome, a clinical variant of Guillain-Barré syndrome that occurs rarely among children. In both patients, this diagnosis was supported by the clinical course and neurophysiologic findings. Plasma serology was positive for Campylobacter jejuni and anti-GQ1b antibodies in one patient and for antimyelin antibodies in the other. This report of two children with Miller Fisher syndrome presenting with intracranial hypertension adds to the findings for a similar patient treated previously, which raises the question concerning the possible role or contribution of benign intracranial hypertension in Miller Fisher syndrome.

Infantile spinal muscular atrophy variant with congenital fractures in a female neonate: evidence for autosomal recessive inheritance

We read with great interest the article published in this journal in 1991 by Borochowitz et al ,1 describing a new lethal syndrome consisting of infantile spinal muscular atrophy (SMA) and multiple congenital bone fractures in two sibs. Recently, another infant with a form of SMA and congenital fractures was reported by Kelly et al ,2 thus validating the suggestion of a distinct and rare form of SMA associated with congenital bone fractures. Autosomal recessive inheritance was suggested in the original report,1 but no history of consanguinity was noted in the second.2 X linked inheritance could, however, not be excluded since these three affected infants were male. Greenberg et al 3 reported four cases with infantile SMA, neonatal death, congenital joint contractures, and the presence of bone fractures in three of the four cases; these cases seem clinically to be similar to the originally reported cases,1 but the pedigree in this report was consistent with X linked recessive inheritance and the gene in this family was mapped to Xp11.3-q11.2.4 Here, we report on a female neonate with a severe, acute, lethal form of SMA and congenital bone fractures, thus excluding X linked inheritance. Furthermore, since this girl was born to first cousin parents, this suggests autosomal recessive inheritance in this rare variant of SMA type 1 with congenital fractures. The girl was born to a 35 year old, G5 P5 mother and a 41 year old father. The parents, of Moroccan origin, were consanguineous, as were the maternal grandparents. They had one healthy son and two healthy daughters, and another son who had died at the age of 3 months in Morocco. The pregnancy was not medically followed but reported by the mother as uneventful. Delivery, recorded as normal by both gynaecologist and mother, …

Transcranial magnetic stimulation and other evoked potentials in pediatric multiple sclerosis

In children, multiple sclerosis is rare and has some clinical and paraclinical differences compared with adults. The assessment of corticospinal motor tracts is expected to be relevant because of their frequent early involvement in this disease. Reported are the results of transcranial magnetic stimulation in two children who presented at 12 and 9 years of age with clinically probable and definite multiple sclerosis, respectively. In Patient 1 the excitatory cortical threshold for the upper limbs was abnormally raised. In Patient 2 the latency of the motor-evoked potentials was considerably increased for the right tibialis anterior muscle, with a slowing of the central conduction time. Although these abnormalities may be consistent with central conduction impairment, they may alternatively suggest early axonal damage because irreversible axonal lesions occurring at the onset of the disease have recently been reported. Testing of central motor tracts, in addition to visual, auditory, and somatosensory pathways, therefore appears appropriate in the multimodal assessment of pediatric patients with suspected multiple sclerosis.

Interet Du Suivi Des Bruits Respiratoires Tracheaux Dans Le Diagnostic De Dysrythmies Respiratoires Nocturnes

SummaryTwenty-six patients underwent a polysomnygraphic study allowing sleep staging and respiratory events scoring with the use of the oronasal flow, abdominal, thoracic and total displacement (Respitracet), and ear oxymetry. Moreover the patients were also equipped with a tracheal microphone giving a power rectified enveloppe (sonospirogram).Eleven patients showed abnormal respiratory events that were scored by visual lecture using all respiratory Parameters (excluding the sonospirogram) and were classified as obstructive central and mixed apneas-hypopneas. Periodic breathing was also appreciated. Detection of the same events was tried with the sonospirogram alone.The sonospirogram could accurately detect snoring and periodic breathing and finally central obstructive mixed apnea (the apneic index being well correlated: P<0.0()1 as well as the mean apnea duration: p < 0.005).In contrast hypopneic events related to snoring could not be accurately appreciated.We conclude that a sonospirogram may be useful ...

The H reflex as a diagnostic tool for Miller Fisher syndrome in pediatric patients

Miller Fisher syndrome (MFS) is characterized by gait ataxia, external ophthalmoplegia and areflexia. Immunohistochemical studies suggest a pathophysiological role for anti-GQ1b antibodies at the paranodal regions of the oculomotor nerves, at some neurons of the dorsal root ganglia (DRG) and at motor nerve terminals. The variability of abnormal electrophysiological findings reported is significant. Nerve conduction studies, H reflex and F waves were performed in three pediatric patients with MFS. The H reflex was absent in all three patients. It was the sole abnormality in two patients whereas the third patient also had extended motor and sensory nerve conduction impairments. The transient character of this isolated absence has been confirmed in one patient. These data point to a proximal demyelinating process near the DRG. This may involve selective demyelination of Ia spinocerebellar afferent fibers originating in muscle spindles. In a pediatric practice, the H reflex seems to be a useful tool in the diagnostic approach to MFS.

Central vein sign differentiates Multiple Sclerosis from central nervous system inflammatory vasculopathies

In multiple sclerosis (MS), magnetic resonance imaging (MRI) is a sensitive tool for detecting white matter lesions, but its diagnostic specificity is still suboptimal; ambiguous cases are frequent in clinical practice. Detection of perivenular lesions in the brain (the “central vein sign”) improves the pathological specificity of MS diagnosis, but comprehensive evaluation of this MRI biomarker in MS‐mimicking inflammatory and/or autoimmune diseases, such as central nervous system (CNS) inflammatory vasculopathies, is lacking. In a multicenter study, we assessed the frequency of perivenular lesions in MS versus systemic autoimmune diseases with CNS involvement and primary angiitis of the CNS (PACNS).

Involvement of Peripheral and Central Nervous Systems in a Valosin-Containing Protein Mutation

Background Inclusion-body myopathy with Pagets disease of the bone and frontotemporal dementia (IBMPFD) is a rare, late-onset autosomal disorder arising from missense mutations in a gene coding for valosin-containing protein. Case Report We report the case of a man carrying the previously described p.Arg159His mutation, who had an unusual axonal sensorimotor neuropathy as the first clinical manifestation of IBMPFD, and for whom diagnosis only became clear 8 years later when the patient developed frontotemporal dementia. Conclusions Peripheral neuropathy is a rare manifestation of IBMPFD. This underdiagnosed disorder should be considered when a patient develops dementia or has signs of Pagets disease.