Central Conduction Time Research Articles

Hypothermia After CPR Prolongs Conduction Times of Somatosensory Evoked Potentials

To investigate the effect of mild hypothermia on conduction times and amplitudes of median nerve somatosensory evoked potentials (SEP) in patients after cardiopulmonary resuscitation (CPR). Patients treated with hypothermia after CPR who underwent SEP recording during hypothermia and after rewarming were selected from a prospectively collected database. Latencies and amplitudes of N9 (peripheral conduction time, PCT), N13, and N20 were measured. The central conduction time (CCT) was defined as peak-peak latency N13-N20. Recordings of 25 patients were assessed by a second observer to determine the intraclass correlation coefficient (ICC). A total of 115 patients were included. The mean body temperature at SEP during hypothermia was 33.1 °C (SD 0.8) and after rewarming 37.1 °C (SD 0.8). Mean latencies of N9, N13, and N20 and mean CCT were longer during hypothermia. There were no consistent differences in amplitudes. There was an almost perfect ICC for assessment of latencies and amplitudes. This study showed that PCT and CCT of median nerve SEP were prolonged during treatment with hypothermia after CPR compared with after rewarming. Amplitudes did not differ consistently.

Multimodality evoked potentials for discrimination of atopic myelitis and multiple sclerosis

AbstractObjectivesTo clarify the differences in multimodality evoked potential findings between patients with atopic myelitis (AM) and those with multiple sclerosis (MS).MethodsA retrospective chart review of 70 consecutive AM patients and 93 MS patients was carried out. All patients were negative for serum anti‐aquaporin‐4 antibody. Visual‐ (VEP), somatosensory‐ (SEP) and motor‐evoked potentials (MEP) recorded at first examination, and magnetic resonance imaging (MRI) findings from the first examination were compared between AM and MS patients.ResultsCompared with MS patients, AM patients showed male preponderance, lower the Expanded Disability Status Scale scores and less frequent spinal cord MRI lesions. Visual impairment and muscle weakness were also less severe in AM patients. Frequencies of abnormal VEP and prolonged central conduction time on lower limb MEP were significantly lower in AM patients than in MS patients (AM vs MS: 9.5% vs 55.6%, and 28.2% vs 54.4%, respectively), whereas frequencies of peripheral nerve involvement in upper and lower limb MEP and upper limb SEP were significantly higher in AM than in MS patients (AM vs MS: 12.8% vs 2.9%, 17.9% vs 2.9% and 33.3% vs 4.4%, respectively). When patients whose EP were examined within 5 years of disease onset were compared, lower frequencies of abnormal VEP and higher peripheral nerve involvement detected by MEP and SEP were observed in AM patients.ConclusionsAM patients have distinct physiological features compared with MS patients, even at the first examination of evoked potentials, which might suggest distinct immunological mechanisms between the two conditions. Multimodality evoked potentials might contribute to the early discrimination of these two disorders.

Prognosis in prolonged coma patients with diffuse axonal injury assessed by somatosensory evoked potentia.

A total of 43 prolonged coma patients with diffuse axonal injury received the somatosensory evoked potential examination one month after injury in the First Affiliated Hospital, School of Medicine, Zhejiang University in China. Somatosensory evoked potentials were graded as normal, abnormal or absent (grades I–III) according to N20 amplitude and central conduction time. The outcome in patients with grade III somatosensory evoked potential was in each case unfavorable. The prognostic accuracy of grade III somatosensory evoked potential for unfavorable and non-awakening outcome was 100% and 80%, respectively. The prognostic accuracy of grade I somatosensory evoked potential for favorable and wakening outcome was 86% and 100%, respectively. These results suggest that somatosensory evoked potential grade is closely correlated with coma severity and degree of recovery. Somatosensory evoked potential is a valuable diagnostic tool to assess prognosis in prolonged coma patients with diffuse axonal injury.

Facial onset sensory motor neuronopathy: not always a slowly progressive disorder

Facial onset sensory motor neuronopathy (FOSMN) is a rare disorder characterized by sensory deficits in the trigeminal territory associated with weakness and wasting of facial muscles [1]. Symptoms usually spread to neck and upper limb (UL) muscles. Usually, the disease duration is slowly progressive [1, 2]. In past reports, temporary response to intravenous immunoglobulin (IVIG) or plasmapheresis (PE) in some patients suggested an inflammatory pathogenesis [2, 3]. More recently, pathologic studies indicated a neurodegenerative mechanism [4]. We describe a rapidly progressive case of FOSMN mimicking amyotrophic lateral sclerosis (ALS). A 70-year-old man presented to our hospital with left UL weakness. He reported a 1-month history of paraesthesia and numbness in left side of face with loss of taste. Two weeks later, numbness involved scalp and neck. At the admission, neurological examination revealed moderate wasting of temporal and masseter muscles, especially the left ones. Fasciculations were present in facial and proximal limb muscles. He had also moderate weakness of neck flexors and trunk muscles, and slight weakness of left arm abductors and flexors. Pinprick and temperature sensation were reduced in the left trigeminal nerve territory. His general laboratory workup including serum lipoproteins, hormones and autoantibodies was unrevealing. Genetic testing for Kennedy’s disease was negative. Cerebrospinal fluid (CSF) analysis revealed 95 mg/dL protein with no oligoclonal bands. Nerve conduction studies (NCS) were normal, needle electromyography (EMG) revealed fibrillations in the left trapezius muscle and denervation-reinnervation changes in the muscles of the upper and lower limbs. Blink reflex showed delayed responses bilaterally. Motor evoked potentials showed an increase of central conduction time. MRI of the brain and spinal cord appeared normal with no evidence of syrinx or malignant roots infiltration. Because of the CSF protein increase, IVIG (2 g/kg in 5 days) was administered. Few weeks later, the patient experienced a subjective improvement in left UL muscle strength, however his overall condition at neurological examination remained unchanged. Two months after disease onset, facial pain increased, becoming continuous and stabbing. Left facial nerve palsy with severe weakness of neck flexors and moderate involvement of proximal and distal left UL muscles was evident. After 9 months the patient’s clinical condition continued to worsen, despite a five PE protocol. Common analgesics, pregabalin, amitriptyline, carbamazepine, tapentadol and tramadol were used in order to treat pain, with poor results. Weakness spread up to the territory of both facial nerves E. Barca (&) M. Russo A. Mazzeo C. Terranova A. Toscano P. Girlanda Department of Neurosciences, University of Messina, Messina, Italy e-mail: emanuelebarca@hotmail.com

Intraoperative Neurophysiological Monitoring in Spinal Root Surgical Interventions

Background and Objective: Surgical interventions around spinal roots may result in rootlets injury and neurological deficits. Multimodal introperative neurophysiological monitoring (MIOM) can allow for early detection and then reversal of nerve roots potential injuries. These utilities have been currently used to evaluate spinal sensorimotor pathways and nerve root function during posterior spinal approches for transpedicular screw fixations in a rotine base in our setting (Vali-e ASR Hospital, Arak, Iran) since 1998. Methods: In three consecutive patients (1 male, 16 years old. and 2 female, 17 and 16 years old) kyphoscoliosis corrections, patient’s history, preoperative physical examination and MIOM were performed using a multimodal 40-channel electrophysiologic monitoring system (Nicolet Endeavor, VIASYS Healthcare, 2005, USA). In all cases somatosensory evoked potentials (SSEPs) and F-wave responses corresponding tothe related myotome, were recorded 2 days prior surgery. The SSEPs, bilateral EMGs of paravertebrals and related muscle, stimulus-evoked evoked EMGs by mid-dural spinal stimulation, stimulus-evoked EMGs through root stimulation (pre/post foraminal) were performed when required during different stages of operation procedure. The compound muscle action potentials (CMAPs) were recorded using a pair of 1 Cm2 golden cup surface electrode. A paired-pulse stimulation consisting of two pulses with 2 ms interstimulus interval (ISI), 100-300 µs duration and 10-40 mA intensity was applied through a surgical probe pair electrode touched to the intact dura, over the midline of dorsal column, 2 segments above the involved root, to evoke constant reproducible EMGs in paravertebrals and/or approperiate myotomes of the segment in both lower limbs. Latency of CMAPs were measured for dorsal culumn, foramen entrance and root exit site stimulations. Following the measurements of the F-wave latencies, the central root conduction time and foramenal segments were calculated and used for further monitoring.The SSEPs of ascending valleis from medial tibial nerve stimulation were recorded at C7 spine and C3´ or C4´of the operation side. A unilateral, sustained loss of 50% of the SSEP amplitude and/or increase by 10% of latency from average values after anesthesia, and SSEP/CMAP waveform change to an asynchronous polyphasic wave, were considered to be pathologic. Drilling and screw positionings were evaluated intraoperatively with standard posteroanterior and lateral radiographs.Results: None of the 3 patients showed significant change in the SSEPsor post-operative radiculopathies distinct from their preoperative presentations. One hour after the start of surgery, when the spinal column was exposed to the operating theatre temperature, a minimal prolongation of latencies as well as amplitude reduction of SSEPs was observed. The SSEP waveforms were not affected subsequently. A reverse change appeared again after paravertebral muscles stitching at the final hour of surgery.In our cases, latencies of different root segments were kept intact during the operation and also during the transfer to the recovery room. Propofol or Propofol/Ketamine mixture plus narcotic is suitable to obtain stable reproducible SSEPs and EMGs. Atracurium or other nondepolarizing skeletal muscle relaxants should be avoided. Muscle relaxants application or mean arterial pressure (MAP) below 70 mmHg may cause bilateral reduction or loss of SSEPs and EMGs. There was no postoperative clinically detectable complication.Conclusions: Findings of our study demonstrated that MIOM should be used in all patients undergoing surgery around spinal roots. Monitoring can practically reduce possibilities of neurological deficit. Futhermore, it can be concluded that the use of SSEPs to evaluate the pedicle screw placement or similar interventions is not an appropriate tool itself, since, , it could be practically limited to sensory fibers of root. In these settings and similar procedures, if IOM is required, alternative multimodal methods with greater sensitivity and efficacy should be explored. To aquire MIOM modalities, close collaboration of an anesthesioloist is nessesary.

The Influence of Aging on Auditory Evoked Potential in Advanced Age Group

Each sensory system has its own time of maturation. The individuation of the exact period of life when brain aging starts is difficult to define. Normally, the amplitude of evoked potentials decreases, and their latency increases from adult to elder life. The absolute latencies of Waves I, III, and V are 0.1 to 0.2 ms longer for subjects aged 50 years and older than for those aged 2030 years. The influence of age on interwave latency is inconclusive but also suggests that there may be an age-related prolongation of 0.1 to 0.2 ms for the IV interpeak interval. Age related changes may be confounded by the presence of sensory hearing loss. Since age effects on central conduction time in the acoustic pathway are still debated, the present study was conducted to assess the effects of aging on central conduction time & compared with the young adult. Auditory evoked potential were studied in twenty five normoacoustic elderly subjects & results were compared with twenty five age and sex matched controls (young adults between 18-25 years age group). The older adults had prolonged wave III & wave V latencies. The interpeak latency I-III and I-V are also prolonged which suggest that aging process is central phenomenon.

Isolated pyramidal tract impairment in the central nervous system of adult-onset Krabbe disease with novel mutations in the GALC gene

This report describes a 60-year-old female patient with Krabbe disease who presented with slowly progressive gait disturbance due to mild spastic paraplegia. Brain magnetic resonance imaging showed high-intensity lesions along the upper parts of the bilateral pyramidal tracts in fluid-attenuated inversion recovery images. Central motor conduction time was prolonged both in the upper and the lower extremities, while central sensory conduction time was normal. The reduced lymphocyte galactocerebrosidase (GALC) activity and two novel mutations in the GALC gene, p.G496S and p.G569S, proved the diagnosis of Krabbe disease. Our findings show that adult-onset Krabbe disease is characterized by isolated pyramidal tract impairment in the central nervous system, both neurophysiologically and radiologically.

BRAINSTEM AUDITORY EVOKED POTENTIAL IN DIFFERENT AGE GROUPS

Brainstem auditory evoked potential is a physiological technique for evaluation of auditory pathway. A number of electrical potentials can be recorded from the human scalp following acoustic stimulation. The potentials which occur within 10 msec of the stimulus onset termed the brain stem auditory evoked potentials (BAEPs). Latency appears to be the most stable measure and in consequence knowledge of the exact limits of normal latency of each wave is important. Since age effects on central conduction time in the acoustic pathway are still debated, the following study was conducted to investigate possible age differences in BAEP component latencies in different age groups. BAEP were elicited from seventy five normoacoustic male subjects aged from 11-60 years. The recorded results are grouped according to patients age ranges of 11-20 (15), 21-30 (15), 31-40 (15), 41-50 (15) and 51-60 (15) years. The absolute peak latency of waves I, III & V and interpeak latency of wave’s I-III, III-V & I-V in various age groups are analyzed. The data collected from both ears showed that increase in age will cause an increase in peak latency and interpeak latency values of all waves. Significant changes in the BAEPs in our study support the possible role of age as contributory factors for normal variations.

Effects of Iron Supplementation on Auditory Brainstem Response in Marginally LBW Infants

LBW infants are at risk of iron deficiency (ID), which is associated with impaired nervous system development and may lead to prolonged auditory brainstem response (ABR) latencies. We hypothesized that iron supplementation shortens ABR latencies in marginally LBW (MLBW, 2000-2500 g) infants. In a randomized, controlled trial, 285 healthy MLBW infants received 0, 1, or 2 mg iron/kg/d of iron supplements from 6 wk to 6 mo of age. ABR absolute wave V latencies and central conduction time (CCT) were measured at the endpoint. There were no significant differences between groups in ABR wave V latencies (n = 218). Furthermore, there were no significantly prolonged ABR latencies in infants with ID (n = 32). CCT was significantly higher in the 2 mg group than in the placebo group (n = 126). However, there were no significant correlations between CCT and iron intake or any iron status variable, suggesting that differences in CCT were not caused by iron. We conclude that iron supplements did not improve ABR latencies, and iron-deficient MLBW infants did not have impaired ABR latencies at 6 mo, suggesting that ABR is not a sensitive measure of impaired neurological development or that mild/moderate ID causes no such impairment in MLBW infants.

Evaluación funcional de sistemas sensoriales mediante potenciales evocados en niños con trastornos del espectro autista

Objective: To evaluate the possible sensorial affectation of the somesthetic system in children with speech disorders, mainly with the autistic spectrum disorders (ASD)through the use of the recording technique for somatosensory evoked potential (SEP).Subjects and methods: We performed a longitudinal retrospective study on 40 children remitted to CIREN'S Laboratory of Evoked Potentials from August 2000 to May 2009. The children presented disorders in language acquisition, most of them within the ASD. The sample was composed of 24 males and 16 females (aged between 2 and 13 years of age). To obtain SEP, recording electrodes were applied on the L4-T12 lumbar region (plexus derivation) and in Cz-Fz cortical region, by stimulating the posterior tibial nerve. Additionally, the auditory brainstem response (ABR) was performed to discard functional disorders of the auditory pathway.Results: 92% of the children studied showed alterations in SEP, of which 65% was related to an increment of central conduction time (CCT); 10% had no bilateral cortical response and 12.5% presented morphologic distortion of the evoked cortical response.ABR was conducted on 29 of the 40 studied children, and it was observed that 75.8% were normal and only 24.1% presented anomalies. Of these, 5 were related to affectation of wave I, another presented bilateral hypoacusia and the remaining one had no evoked response, where the bilateral form of dysfunction predominated.Conclusions: Our results suggest a possible relation between the dysfunction of the somesthetic system and language retard. The affectation of this system was greater than the auditory ones in the patients studied.

Effects of the Chinese Yi-Qi-Bu-Shen Recipe extract on brainstem auditory evoked potential in rats with diabetes

This study was designed to investigate the effects of the Chinese Yi-Qi-Bu-Shen Recipe (YB) on brain stem auditory evoked potential (BAEP) in diabetic rats and on the protection of the diabetic rat brain's functional lesion. Thirty-three male rats were randomly divided into three groups: the normal control group (NC), the diabetic group (DM), and the diabetic rats treated with YB group (DM+YB). Blood glucose and body weight were measured every three weeks. After six weeks, the serum insulin, blood biochemical indices, superoxide dismutase, malondialdehyde, monoamine neurotransmitters, and BAEP were measured. Compared with the NC group, the waves III, V PLs, and the I-III, I-V IPLs of BAEP in the DM group were significantly delayed (all P<0.05). However, YB-treated diabetic rats maintained a normal brainstem function over the experimental period. Compared with the NC group, the waves I, III, V PL, and waves I-III, III-V and I-V IPLs of BAEP in the DM+YB group were very close (all P>0.05). On the other hand, compared with the DM group, the III, V PLs and the I-III, I-V IPLs of BAEP in the DM+YB group were significantly improved. It was discovered that the central conduction time of rats with diabetes had a close correlation with serum insulin, blood glucose, malondialdehyde, and insulin resistance index. Our results suggest that YB extract has a beneficial effect in preserving the brain's electrophysiological function in diabetic rats, likely through its antihyperglycemic activity, ability to reduce insulin resistance, and antioxidant activity.

P18.3 Peripheral and central (CCT) conduction times to proximal and distal muscles of lower limbs: methodological aspects and clinical application in MS patients

P18.3 Peripheral and central (CCT) conduction times to proximal and distal muscles of lower limbs: methodological aspects and clinical application in MS patients

Whole-body hypothermia has central and peripheral influences on elbow flexor performance

The superimposed twitch technique was used to study the effect of whole-body hypothermia on maximal voluntary activation of elbow flexors. Seven subjects [26.4 ± 4 years old (mean ± SD)] were exposed to 60 min of either immersion in 8°C water (hypothermia) or sitting in 22°C air (control). Voluntary activation was assessed during brief (3 s) maximal voluntary contractions (MVCs) and then during a 2 min fatiguing sustained MVC. Hypothermia (core temperature 34.8 ± 0.9°C) decreased maximal voluntary torque from 98.2 ± 1.0 to 82.8 ± 5.8% MVC (P < 0.001) and increased central conduction time from 7.9 ± 0.4 to 9.1 ± 0.7 ms (P < 0.05). Hypothermia also decreased maximal resting twitch amplitude from 17.6 ± 4.0 to 10.0 ± 1.7% MVC (P < 0.005) and increased the time-to-peak twitch tension from 55.4 ± 4.0 to 79.0 ± 11.7 ms (P < 0.001). During the 2 min contraction, hypothermia decreased initial torque (P < 0.01) but attenuated the subsequent rate of torque decline (control from 95.5 ± 4 to 29.4 ± 8% MVC; and hypothermia from 85.3 ± 8 to 37.3 ± 5% MVC; P < 0.01). Cortical superimposed twitches increased as fatigue developed but were always lower in the hypothermic conditions. Cortical superimposed twitches increased from a value of 0.4 ± 0.3% MVC prefatigue to 3.9 ± 1.4% MVC postfatigue (P < 0.001) in the hypothermic conditions and from 1.7 ± 0.9 to 5.5 ± 2.3% MVC in control conditions. Our results suggest that hypothermia decreases MVCs primarily via peripheral mechanisms and attenuates the rate of fatigue development by reducing central fatigue.

Air pollution is associated with brainstem auditory nuclei pathology and delayed brainstem auditory evoked potentials

We assessed brainstem inflammation in children exposed to air pollutants by comparing brainstem auditory evoked potentials (BAEPs) and blood inflammatory markers in children age 96.3 ± 8.5 months from highly polluted ( n = 34) versus a low polluted city ( n = 17). The brainstems of nine children with accidental deaths were also examined. Children from the highly polluted environment had significant delays in wave III ( t(50) = 17.038; p < 0.0001) and wave V ( t(50) = 19.730; p < 0.0001) but no delay in wave I ( p = 0.548). They also had significantly longer latencies than controls for interwave intervals I–III, III–V, and I–V (all t(50) > 7.501; p < 0.0001), consisting with delayed central conduction time of brainstem neural transmission. Highly exposed children showed significant evidence of inflammatory markers and their auditory and vestibular nuclei accumulated α synuclein and/or β amyloid 1–42. Medial superior olive neurons, critically involved in BAEPs, displayed significant pathology. Children's exposure to urban air pollution increases their risk for auditory and vestibular impairment.

A clinically complex form of dominant optic atrophy (OPA8) maps on chromosome 16

Dominant optic atrophy (DOA) is genetically heterogeneous and pathogenic mutations have been identified in the OPA1 and OPA3 genes, both encoding for mitochondrial proteins. We characterized clinical and laboratory features in a large OPA1-negative family with complicated DOA. Search for mitochondrial dysfunction was performed by studying muscle biopsies, fibroblasts, platelets and magnetic resonance (MR) spectroscopy. Genetic investigations included mitochondrial DNA (mtDNA) analysis, linkage analysis, copy number variation (CNV) analysis and candidate gene screening. Optic neuropathy was undistinguishable from that in OPA1-DOA and frequently associated with late-onset sensorineural hearing loss, increases of central conduction times at somato-sensory evoked potentials and various cardiac abnormalities. Serum lactic acid after exercise, platelet respiratory complex activities, adenosine triphosphate (ATP) content in fibroblasts and muscle phosphorus MR spectroscopy all failed to reveal a mitochondrial dysfunction. However, muscle biopsies and their mtDNA analysis showed increased mitochondrial biogenesis. Furthermore, patient's fibroblasts grown in the galactose medium were unable to increase ATP content compared with controls, and exhibited abnormally high rate of fusion activity. Genome-wide linkage revealed a locus on chromosome 16q21-q22 with a maximum two-point LOD score of 8.84 for the marker D16S752 and a non-recombinant interval of ∼ 6.96 cM. Genomic screening of 45 genes in this interval including several likely candidate genes (CALB2, CYB5B, TK2, DHODH, PLEKHG4) revealed no mutation. Moreover, we excluded the presence of CNVs using array-based comparative genome hybridization. The identification of a new OPA locus (OPA8) in this pedigree demonstrates further genetic heterogeneity in DOA, and our results indicate that the pathogenesis may still involve mitochondria.

Fatigue in Colchicine Myopathy: A Study of Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) is a noninvasive method to assess brain physiology and plasticity. TMS has shown that nervous system excitability may be altered in myopathy, and it presents with motor disinhibition on cortical and subcortical levels. Eight patients who had colchicine myopathy were observed to have fatigue, but they did not have significant weakness. This study investigated whether there was central reorganization to compensate for their muscle strength. TMS was applied to study the central compensative mechanism. The TMS parameters included motor evoked potentials, central conduction time, cortical silent period and intracortical inhibition of paired TMS paradigms. TMS results did not show any significant differences between patient and control groups. Although central reorganization may occur in patients with hereditary myopathy to compensate for muscular strength, our study did not find any change in cortical excitabilities in acquired myopathy due to colchicine. Muscle fatigue may precede weakness as an early symptom of myopathy.

A method to measure the distribution of latencies of motor evoked potentials in man

Objective To measure the intra-individual distribution of the latencies of motor evoked potentials (MepL) using transcranial magnetic stimulation. Methods We used the triple stimulation technique (TST) to quantify the proportion of excited spinal motor neurons supplying the abductor digiti minimi muscle in response to a maximal magnetic brain stimulus ( Magistris et al., 1998). By systematically manipulating the TST delay, we could quantify the contribution of slow-conducting motor tract portions to the TST amplitude. Results Our method allowed the establishment of a MepL distribution for each of the 29 examined healthy subjects. MepLs of 50% of the motor tract contributing to the motor evoked potential laid between the intra-individually minimal MepL (MepL min) and MepL min + 4.9 ms (range 1.6–9.2). The individual MepL distributions showed two peaks in most subjects. The first peak appeared at a MepL that was 3.0 ms longer on average (range 0.7–6.0) than MepL min; the second peak appeared at MepL min + 8.1 ms on average (range 3.7–13.0). Conclusions Slow-conducting parts of the motor pathway contribute notably to the motor evoked potential. Our data suggest a bimodal distribution of central conduction times, which might possibly relate to different fibre types within the pyramidal tract. Significance We present a non-invasive method to assess slow-conducting parts of the human central motor tract.

Neonatal Somatosensory Evoked Potentials: Maturational Aspects and Prognostic Value

The aim of this prospective study was to evaluate the diagnostic role of somatosensory evoked potentials (SEP) during the neonatal period with regard to maturational changes and prognostic value in perinatal hypoxic-ischemic encephalopathy. Median nerve SEP analysis was performed in 31 healthy infants (group A1, 33-35 weeks, n = 10; group A2, 36-37 weeks, n = 11; group A3, 38-41 weeks, n = 10) and in 10 term infants with hypoxic-ischemic encephalopathy (group B). Cortical latency N1 and central conduction time values were analyzed for group A in relation to postconceptional age and postnatal age and for group B in relation to degree of hypoxic-ischemic encephalopathy and neurodevelopmental outcome (at the mean age of 6.6 + or - 1.6 years). Central latencies were correlated with postconceptional age but not postnatal age. Mean N1 latency and central conduction time values did not differ significantly between groups A1 and A2; the most pronounced decrease was between groups A2 and A3 (postconceptional ages 36-37 vs 38-41 weeks). In group B, central latencies were prolonged, compared with controls (P < 0.001), but were not significantly correlated with long-term outcome in patients with moderate hypoxic-ischemic encephalopathy (n = 6). Neonatal SEP analysis thus is an objective and noninvasive method for assessing functional integrity of the somatosensory pathway. In term infants, SEPs are a valuable additional tool for early diagnosis of hypoxic-ischemic encephalopathy, but are not prognostic of neurodevelopmental long-term outcome in moderate hypoxic-ischemic encephalopathy.

Somatosensory evoked potentials in epileptic children treated with carbamazepine or valproate in monotherapy – a preliminary study

Data from the literature suggest that long-term therapy with various antiepileptic drugs can be responsible for the functional disturbances within the nervous system e.g. peripheral neuropathy and encephalopathy. Useful and non-invasive instruments for evaluation of even subclinical nerve conduction abnormalities in somatosensory tracts are somatosensory evoked potentials (SEPs). The aim of this study was to assess the potentially drug-induced abnormalities in the SEP parameters in epileptic children, treated chronically in monotherapy with one of the two most often used antiepileptic drugs: valproate (VPA) or carbamazepine (CBZ). SEP from left median nerve stimulation were recorded in twenty children with idiopathic/cryptogenic epilepsy treated in monotherapy with CBZ (9 patients) or VPA (11 patients). The mean age of the patients was 13.4 ± 2.9 years (range 7-17 years). The plasma concentrations of the drugs were consistently within therapeutic range. The mean duration of treatment was eight months. The control group consisted of twenty-four age-matched children with tension type headache. The latencies of the components: N9, N13, N20, P25 and the peripheral conduction time (PCT) and central conduction time (CCT) were analyzed. No significant differences in all analyzed SEP parameters between the epileptic and control children were found. Our results indicate that during the first 8 months from the beginning of antiepileptic treatment in children, monotherapy with VPA or CBZ does not induce nerve conduction disturbances within both the peripheral- and the central part of the somatosensory tracts, detected in SEP examination.

脳幹聴覚誘発電位の中枢伝導時間延長が手がかりとなり，Ｃｘ３２に新規の遺伝子変異が確認されたＣＭＴＸ１の成人男性例

CMTX1, the second most common type of inherited hereditary motor and sensory neuropathy (HMSN), is associated with mutations of the gene for the gap junction protein connexin 32 (Cx32). In this condition, central conduction velocity is known to be delayed, presumably because mutated Cx32 is expressed in oligodendrocytes. A 45-year-old man presented with a 5-year history of progressive gait disturbance due to leg muscle weakness. The family history revealed that the mother had also progressive gait disturbance in her early 40s, and the younger sister could not walk faster than before at the age of 41. On neurological assessment, the patient exhibited pes cavus, distal muscle atrophy and weakness, and absence of the knee and ankle jerks. Touch sensation was impaired in the both feet. Motor and sensory nerve conduction velocities were reduced to 30-36 m/s with mild temporal dispersion. Sural nerve biopsy revealed diffuse loss of large myelinated fibers with the remaining large and intermediate nerve fibers being frequently surrounded by a thin myelin sheath. Onion bulb formation was only occasional and mild in degree. His hearing acuity was normal on pure-tone audiometry, but BAEP test demonstrated prolonged central conduction time (-I wave 1.8 milliseconds, I-V wave 6.4 milliseconds). The BAEP findings prompted us to choose Cx32 gene to analyze first to find a novel mutation of two (A and T) base pairs deletion at codons 277 and 278 (Met93fs). Thus, the present case indicates that Cx32 gene mutation should be targeted first in case of HMSN with abnormal BAEP.