11. cranial nerves stimulation in the posterior fossa with transcranial magnetic stimulation (tms)
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(CT) and an audiometric assessment. All these are needed to deter-mine if surgery is recommended for the patient.
Case report: A 6-year-old male with atresia of the left EAC.BAER study showed a left conductive hearing loss. No alterations
were found on the right side.Conclusion: A third of the subjects with EACA are not candidates
for surgical correction. Proper selection of the patients for surgicaltreatment maximizes the opportunity for hearing recovery and min-imizes the possible surgical complications such as lesion of the facialnerve. In most cases, the radiological ndings in the middle eardetermine the surgical indication. In uncooperative patients and inchildren, BAERs are useful to detect the involvement of other struc-tures of the auditory pathway. Determining the level of cochlearfunction in each ear is crucial in these patients in order to preventoperating on an ear with little potential for hearing improvement.
8. Preoperative Magneto encephalography (magnetic sourceimaging) and intraoperative stimulation cortical mapping cor-relationM. Gonzlez-Hidalgo 1, C.J. Saldaa Galan 2, F. Maeztu 3,C. Amo1, A. Fernndez 1, T. Ortiz 3, C. Franco Carcedo 1, P. MataGonzlez 1 (1Neurophysiology, Complutense University, Madrid,Spain, 2Neurosurgery, Complutense University, Madrid, Spain,3Magnetoencephalography Center, Complutense University,Madrid, Spain)
Introduction: The management of lesions involving eloquentcortex entails signicant functional risk. Presurgical localization ofthese functional areas can aid in planning the therapeutic optionsand surgical approaches. Magneto encephalography is a non-inva-sive technique that provides preoperative functional location of mo-tor, somatosensory and language cortical areas and epileptic activityrelated to anatomical landmarks.
Objective: To validate presurgical functional information obtainedfrom 7 magnetic sources imaging in patients operated while awakewith realization of intraoperative cortical stimulation mapping.
Patients and methods: Six patients (Mean age: 44 years, ranges:970; 2 females and 4 males) with intra axial cerebral lesions locatedclose to eloquent brain cortex were studied preoperatively andunderwent magnetic source imaging techniques. MEG data were col-lected using a 148-channels Magnes 500WH biomagnetometer. Thepatients then underwent craniotomy while awake and direct corticalelectrical stimulation, mapping areas related to motor, somatosen-sory and language functions. The accuracy of presurgical studieswas assessed by gross visual comparison and by the integration ofMEG data into a neuronavigational system.
Results and conclusions: MEG data show reasonably good con-cordance with epileptic activity, somatosensory and language intra-operative mapping, letting us achieve anatomo-functionalpresurgical planning that must be validated by intraoperative corti-cal stimulation.
9. Neurophysiological ndings in Lafora disease: A detailed studyof a patientS. Prez, M.Gratacos, N. Raguer, l. Pericot, A. Ferr,T. Minoves (Clinical Neurophysiology and Neurology Depart-ments, Vall Hebron Hospital, Barcelona, Spain)
Obiective: To report on the neurophysiological ndings of apatient with the typical clinical and paraclinical features of Laforasdisease.
Patient andmethods: Electroencephalogram, somatosensory, vi-sual and brainstem evoked potentials, electromyography and trans-cranial magnetic stimulation (TMS) were performed on a 50-year-old woman presenting progressive spastic paraparesia and bladderdysfunction. Muscle biopsy was consistent with Lafora disease. Rou-tine laboratory determinations, cranial and medullar MRI and oph-thalmologic studies were normal.
Results: The EEG showed deterioration of the background activ-ity and occipital bilateral spikes. Visual-Evoked Potentials and Brain-stem-Evoked Potentials were normal. However, Somatosensory-Evoked Potentials showed an increased central conduction time withhigh amplitude responses. Transcranial magnetic stimulation elic-ited abnormal cortical responses from upper and lower extremities.
Conclusion: Giant evoked potentials, generalized epileptiformdischarges and occipital spikes are common ndings in Lafora dis-ease that can help us in identifying asymptomatic patients or thosepresenting unspecic symptomathology.
10. Analysis of the responses in the Recovery Cycle of the BlinkReex (RCR)A. Polo, A. Esteban, A. Traba, J. Prieto, A.B. Blanco,B. Godes (Dept. of Clinical Neurophysiology, Hospital Universi-tario G, Maran, Madrid, Spain)
Background and objective: RCR results published in the litera-ture show a great variability probably due to different criteria andmethods used.
Patients and methods: Six normal RC and 35 facilitated RC werestudied. A paradigm of the same intensity paired stimulation wasused, with inter-stimuli intervals (ISIs) of 100, 300, 500, 1000 and1500 ms. The recovery of rectied and averaged R response was calcu-lated in 4 ways: total area, inc1uding 40 and 50 ms windows (A W40and A W50) from the start of response and maximum amplitude.
Results: Signicant differences between both groups (p < 0.00l)were found in the area for ISIs of 100, 300 and 500 ms, but not forISI of 1000 and 1500 ms. The amplitude showed a great variability.
Correlation among the four methods was greater for total areaand A W40 values. Recovery mean values for A W 40 were 0.54(ISI 100), 3.4 (ISI 300) and 46.9 (ISI 500). In the facilitated groupthe mean va1ues were 38.5 (ISI 100), 71.9 (ISI 300) and 80.1 (ISI500). The frequency of response was remarkably different: 1/ 6 innormal and 34/35 in facilitated group for ISI 100; 5/ 6 and 35/35,respectively, for ISI 300 and 100% in both groups for the rest of ISIs.
Conclusion: A W40 method shows a high correlation with totalarea analysis and it is of easy application.
11. Cranial nerves stimulation in the posterior fossa with Trans-cranial Magnetic Stimulation (TMS)A. Esteban, A. Traba, J. Pri-eto (Department of Clinical Neurophysiology, HospitalUniversitario G, Maran, Madrid, Spain)
Background and objectives: Cranial nerve evaluation with TMSis usually performed only in the facial nerve. Data obtained fromthe accessory and hypoglossal nerves using TMS are described.
Method: TMS over posterior fossa was applied on both sides in 6normal subjects. Short diameter, eight-shaped coil was employed.Responses were recorded with cutaneous electrodes in the trapeziusmuscle for the accessory nerve and enoral electrodes over the tonguefor the hypoglossal nerve.
Society Proceedings / Clinical Neurophysiology 120 (2009) e133e145 e135
Results: Compound muscle action potentials (CMAPs) wereobtained systematically in both territories with the coil placed overthe inion-mastoid line, 67 cm away from the inion. Mean values oftrapezius CMAP were 4.1 ms of latency and 113 mV of amplitude.Tongue CMAP values were of 4.1 ms of latency and 6.6 mV ampli-tude. Latencies were not modied neither coil displacement throughthe inion-mastoid line nor with the increment of the stimulus inten-sity. CMAPs obtained with electrical stimulation of the most proxi-mal peripheral segments of the nerves showed values of 3 ms and11.4 mV in the trapezius muscle and .3 ms and 7.1 mV in the tongue.
Conclusions: The xed CMAPs latency obtained despite the vari-ations in the TMS point support the existence of a preferential area ofnerve activation. This area may in all probability be related to theexit skull foramen of the nerves.
12. Corticospinal pathway evaluation in HIV associated myelop-athyB. Godes, J. Prieto, A. Esteban, A. Traba, A. Polo (Dept. ofClinical Neurophysiology, Hospital G, Universitario G, Maran,Madrid, Spain)
Objective: Autopsy studies have shown that vacuolar myelop-athy is the most frequent cause of spinal cord disease in HIV pa-tients. This disorder is usually developed in the advanced stagesof AIDS and in association with other dysfunctions of the nervoussystem.
Four long evolution AIDS patients with associated myelopathyhave been studied. Somatosensory-evoked potentials from median(SEPm) and posterior tibial nerves (SEPpt) and motor central conduc-tion (MCC) with transcranial magnetic stimulation were evaluated inall of them. Motor-evoked potentials (MEPs) were recorded in trape-zius, rst interosseous dorsalis (FID) and tibialis anterior (TA)muscles.
In one patient, MEPs were markedly delayed in trapezius and FIDand absent in TA. SEPpt and SEPm were very normal too. The otherpatients show slightly delayed MEPs in trapezius and mildly delayedin FID and TA. SEPpt were severely impaired and SEPm were onlymildly abnormal in two of them.
The important abnormalities found in SEPt and in MCC to the TArelated to the mildly delayed responses in SEPm and MCC to FIDpoint to a caudo-cranial gradient of lesion in this myelopathy. Theabnormalities observed in trapezius MEPs suggest the associatedinvolvement of supraspinal segments of the corticospinal pathway.
Conclusion: Corticospinal evaluation in HIV associated-myelopa-thy shows a caudo-cranial gradient of lesion and supraspinalinvolvement.
13. Event-related potentials (N 400) in autistic childrenM.Mndez, O. Sans, B. Abril, J.R. Valdizan (Servicio de Neurosiolo-gia Clinica, Hospital Universitario Miguel Servet, Zaragoza, Spain)
Objective: The present study evaluates the inuence of thesemantic context on the N400 activity (latency, amplitude and scalpdistribution), in autistic and Asperger children in comparison to nor-mal children.
Materials and methods: We studied four autistic children, sixwith Asperger syndrome and ve