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ORIGINAL ARTICLE
Year : 2010  |  Volume : 5  |  Issue : 1  |  Page : 12-17
 

Neurophysiologic findings in children with spastic cerebral palsy


1 Department of Physiology, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha, India
2 Department of Opthalmology, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha, India
3 Department of Pediatrics, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha, India
4 Department of Anatomy, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha, India

Date of Web Publication22-Jul-2010

Correspondence Address:
Ruchi Kothari
Department of Physiology, MGIMS, Sewagram, Wardha - 442 102
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1817-1745.66671

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   Abstract 

Context : Cerebral palsy (CP) is a heterogeneous group of permanent, non-progressive motor disorders of movement and posture caused by chronic brain injuries. It is the most common cause of physical disability in childhood; spastic cerebral palsy being the most prevalent of its various forms. There is scanty information about the neurophysiologic investigations in children diagnosed as having spastic CP. Aims : The aim of the study was to investigate the relationship between abnormal VEP and BAEP findings with different clinical parameters in children with spastic cerebral palsy. Materials and Methods : Fifteen children with spastic CP in the age range 4 months to 10 years participated in this study. Evaluation of VEPs, brainstem evoked potentials (BAEPs) were performed in all study patients as well as 35 healthy children as controls. The study was conducted after obtaining ethics committee approval and informed consent of parents. Statistical Analysis Used : Significance of difference in the mean values of different parameters in different groups was assessed by Student's "t" test and the P value <0.05 was considered to be significant. All the values were expressed as mean ± 1 Std. Deviation. Results : A significant difference was found in the VEP latencies and amplitude between the subjects with CP and controls. Striking BAEP abnormalities in CP patients include prolongation of absolute latency of wave V, interpeak latencies of III-V and lowered I-V ratio. Abnormal VEPs and BAEPs in children with bilateral spastic cerebral palsy demonstrated a correlation with the presence of moderate to severe developmental delay. Conclusions : The differences in VEPs and BAEPs were determined between CP children and healthy children. The abnormalities found are probably linked to the neurological deficits present in cases of cerebral palsy.


Keywords: Brainstem evoked potential, developmental delay, spastic cerebral palsy, visual evoked potentials


How to cite this article:
Kothari R, Singh R, Singh S, Jain M, Bokariya P, Khatoon M. Neurophysiologic findings in children with spastic cerebral palsy. J Pediatr Neurosci 2010;5:12-7

How to cite this URL:
Kothari R, Singh R, Singh S, Jain M, Bokariya P, Khatoon M. Neurophysiologic findings in children with spastic cerebral palsy. J Pediatr Neurosci [serial online] 2010 [cited 2019 Apr 19];5:12-7. Available from: http://www.pediatricneurosciences.com/text.asp?2010/5/1/12/66671



   Introduction Top


Cerebral palsy (CP) is a heterogeneous group of permanent, non-progressive motor disorders of movement and posture caused by chronic brain injuries that originate in the prenatal, perinatal, or postnatal period. It is the most common cause of physical disability in childhood. [1],[2]

The four major subtypes of CP are spastic, athetoid, ataxic, and mixed cerebral palsy, with spastic forms being the most common (65%). [3] CP prevalence is increasingly encountered in neonatal clinics since more number of premature infants survives because of better neonatal care made available these days.

Besides motor deficits in cerebral palsy, the other causes of handicap are the associated disabilities, in particular intellectual impairment, epilepsy, speech defects, disorders of vision and hearing, and specific educational and behavioral abnormalities, with the result that the majority of sufferers cannot take their place in normal society [4],[5],[6] (Crothers and Paine, 1959; Henderson, 1961; Ingram, 1964a).

In recent years, the neurophysiologic examination of children with CP has been of increasing interest to both pediatricians and vision researchers because it provides new insights into mechanisms of brain damage and repair in CP. However, there are only very few reports on electrophysiological investigations on children having cerebral palsy [7],[8],[9],[10] and on Visual Evoked Potentials (VEPs) along with Brainstem Auditory Evoked Potentials (BAEPs) in children with CP in this part of the world.

Hence the present study was undertaken to investigate children with spastic cerebral palsy using VEPs and BAEPs and correlate the electrophysiological findings with clinical features.


   Materials and Methods Top


The study was conducted in the Neurophysiology Unit of the Department of Physiology. A total of 50 subjects were investigated for the evaluation of VEPs and BAEPs after obtaining ethics committee approval for the present study. Fifteen children with spastic CP in the ages ranging from 4 months to 10 years participated as patient group in this study. A control group of 35 children with the same age range and with no significant birth history or visual anomaly was also tested. The number of controls was two times greater than the study group to increase statistical power of this study. Data of spastic CP children were collected retrospectively regarding patient's age, pre-, peri- and postnatal events, and history of epilepsy. Clinical eye examinations included observation of fixation, following objects, pupillary reflexes, refraction, and fundus examination.

Recording procedure for VEP and BAEP

The recording was done using RMS EMG.EP MARK II machine manufactured by RMS Recorders and Medicare System, Chandigarh. The stimulus for VEP recording was a monocular flash from light-emitting diode goggles that were held lightly over the infants' eyes. Flashes were presented at 0.5 per second. Silver cup electrodes were attached with paste and tape, with impedances below 5 kilo-ohms. As per 10-20 International System of EEG placements, the reference electrode (Fz) was placed 12cm above the nasion, the ground electrode (Cz) at the vertex and the active electrode (Oz) at approximately 2 cm above the inion. A band pass of 1 to 100 Hz was employed, the gain was 10,000, the sweep was 1 sec, and automatic artifact reject routine was employed. For BAEP recording, same surface electrodes were used and placed at the vertex (Cz), both ear lobes (Ai and Ac) and forehead (ground). Monoaural auditory stimulus consisting of rarefaction clicks were delivered through an electrically shielded earphone at a rate of 11.1/sec. contra-lateral ear was masked with pure white noise 40 dB below that of BAEP stimulus. A band pass of 150-3000 Hz was used to filter out undesirable frequencies in the surrounding. Responses to 2000 click presentations were averaged for 10 msec.

The testing procedures were explained to a parent of each subject who volunteered to participate and a consent form was signed.

Parameters studied

  • The absolute latencies of the peaks of positive wave P2 and the negative waves N1 and N2 were recorded. The amplitude of P2 is measured from the peak of N2 to the trough of P2 (N2 - P2). The absolute difference in the components evoked by the right eye and left eye stimulation (inter ocular differences) are also determined.
  • BAEP threshold for each ear with absolute latencies of I, III, V waves, interpeak latencies of I-III, III-V, I-V and ratio of V to I amplitude (V:I) were considered from recordings for comparison among the two groups.



   Results Top


VEPs and BAEPs were recorded in the children with CP and compared with healthy controls. The VEP parameters of all the 15 children with CP are given in [Table 1]. The lowest latency obtained was 111.9 msec and highest value was 146.9 msec with maximum amplitude of the most prominent positivity as 13.24 μv. The range of variation in interocular difference for latency was 1.2 to 16.6 msec and for amplitude was 0.14 to 8.1 μv.

The mean latencies and amplitude of Flash VEP records in the patient group and control group have been tabulated in [Table 2]. It is quite evident from the observations on VEP that there is a peculiar characteristic which is outstandingly seen in the patient group i.e. a marked delay in the latency as well as a reduction in the amplitude when compared with the controls. The means for all VEP parameters of patient group were statistically different from the control group (P<0.05).

Apart from this, the variations in VEPs records in our study were seen as:

  1. Unusual and improper waveform as obtained in Case No.2 having CP with microcephaly, mental retardation with seizure disorder.
  2. Monocular delayed latency and reduced amplitude as in Case No.8 having CP with typical febrile seizure and mental retardation.
  3. Abnormally delayed latencies and missing components as in:
    • Case no.5 with CP with microcephaly, seizure disorder, mental retardation with global developmental delay with corpus callosal agenesis.
    • Case no.7 with CP with microcephaly, mental retardation with global developmental delay with B/L primary optic atrophy.
  4. "W" Pattern or bifid P wave morphology as in:
    • Case no.1 with CP with microcephaly, seizure disorder, delayed milestones, mental retardation and partial corpus callosal agenesis
    • Case no.4 with CP with microcephaly, global developmental delay with seizure disorder
  5. Broadened "P wave" was obtained in case no.14 having CP with frontal lobe atrophy.
  6. Absent waveform was observed in
    • Case no. 13 with CP with sensorineural hearing loss (SNHL). Its MRI revealed cerebral atrophy in B/L hemispheres.


Out of the total 15 cases, the presenting features of 10 children with spastic CP along with some associated abnormalities such as microcephaly, mental retardation, delayed development and others are elucidated in [Table 3].

The above mentioned associated disorders found along with spastic CP are supported by CT and MRI investigations and the diagnosis was confirmed with the help of pediatrician's opinion. The peculiar neurophysiological findings in these 10 cases have been represented in [Table 4].

As far as the BAEP recordings are concerned, it is observed that average BAEP threshold for control group was 32.00 ±4.06 dB for left ear and 34.29 ± 5.02 dB for right ear whereas in patient group it was estimated as 44.67 ± 24.75 dB for left ear and 53.33 ± 28.45 dB for right ear.

The BAEP parameters of all the 15 children with CP are shown in [Table 5]. and mean latencies and amplitudes of BAEP waveforms are depicted in [Table 6]. Striking BAEP abnormalities in CP patients include prolongation of absolute latency of wave V, interpeak latencies of III-V and lowered V-I ratio as compared to the controls. The difference of means of all the BAEP parameters was statistically significant between the two groups (P<0.05). Abnormal VEPs and BAEPs in children with spastic cerebral palsy demonstrated a significant correlation with the presence of global developmental delay.


   Discussion Top


This article describes neurophysiological study using flash VEPs and BAEPs in children with CP. It was observed that those children who had other neurological symptoms associated with CP showed extensive deviation from the regular pattern of waveforms obtained in VEP investigations some of which are depicted in the [Figure 1]. This is in consonance with the notion put forward by previous workers that children with CP have abnormalities of the visual sensory and motor pathways at rates exceeding those detected in neurologically normal children. [11],[12],[13],[14],[15],[16],[17]

In a recent neurophysiologic study [9] on CP patients, increased latencies of VEPs were reported to occur more frequently with alterations in the optic radiation supported by MRI findings. Similar results are obtained in our study in those patients where their MRI findings reveal cerebral disorders such as corpus callosal agenesis, frontal lobe atrophy, cerebral atrophic changes etc.

It has been documented in the past [18] that microcephaly leads to more than 40% reduction in VEP amplitude. The small head size might be a possible cause of reduced VEP amplitudes found in microcephalic children of the present study.

The abnormal flash VEP findings of our study in cases of CP with developmental delay are in agreement with a most recent study [10] in children with bilateral spastic CP in which they have demonstrated significant correlation of VEP with moderate to severe developmental delay.

Nowadays the neurophysiologic techniques especially VEPs are able to demonstrate the brain plasticity in children with cerebral palsy. The mechanisms of plasticity have been postulated as a change in the balance of excitation and inhibition; a long-term potentiation or long-term depression; a change in neuronal membrane excitability; the anatomical changes-formation of new axon terminals and new synapses. [2]

It has been suggested that children with CP have a remarkable ability to recover from early brain injures. The utility of the neurophysiologic investigations like VEPs in the determination of brain reorganization and repair in patients with cerebral palsy (CP) has been described in a study. [9] According to this, VEP can be a useful tool in the determination of brain plasticity in children with CP as it has been suggested that VEP latencies are valuable estimators of neuronal injury and even predictors of later intellectual performance. [19]

High frequency of abnormal BAEP has been reported in children with spastic cerebral palsy. The BAEP abnormality has been significantly related by previous researchers to term delivery, perinatal etiology of cerebral palsy, visual abnormality, inability to walk independently and many more aspects. In a retrospective study on 75 children with spastic cerebral palsy, 22.7% had abnormal BAEP. [20] In our study profound sensorineural hearing loss (SNHL) was observed in case no.13 with CP along with cerebral atrophy. Bilateral mild to moderate SNHL was evident in a case no. 2 with CP along with MR, microcephaly and seizure disorder [Figure 2]. Moderate SNHL was also seen in right ear of case no.4 who had  Eustachian tube More Details defect in the same ear and in case no.5 who had raised threshold in left ear.


   Conclusion Top


The differences in VEPs and BAEPs were determined between CP children and healthy children. It is concluded that VEPs of the patient group revealed a marked delay in the latency as well as a reduction in the amplitude apart from certain variations in the waveforms. BAEP abnormalities in CP patients include prolongation of absolute latency of wave V, interpeak latencies of III-V and lowered V-I ratio as compared to the controls. The average threshold for hearing also greatly increased in the patient group as compared to controls. The abnormalities found are probably linked to the neurological deficits present in cases of cerebral palsy although the exact etiology remains to be unleashed. Further to conclude, since VEPs and BAEPs are non-invasive neurophysiological investigations; they can serve as important tools in the diagnostic work up of spastic cerebral palsy.


   Acknowledgements Top


We gratefully acknowledge the support rendered by the Dean, MGIMS & Secretary, KHS. Special thanks to our statistician Dr. Bharambe for his valuable help.

 
   References Top

1.Morris C. Definition and classification of cerebral palsy: A historical perspective. Dev Med Child Neurol Suppl 2007;109:3-7.  Back to cited text no. 1      
2.Surveillance of Cerebral Palsy in Europe. Surveillance of cerebral palsy in Europe: A collaboration of cerebral palsy surveys and registers. Dev Med Child Neurol 2000;42:816-24.  Back to cited text no. 2      
3.Ghai OP. Central nervous system. In: Ghai OP, editor. Essentials pediatrics. 6th ed. New Delhi: CBS Publishers; 2004. p. 540.  Back to cited text no. 3      
4.Crothers B, Paine RS. The Natural History of Cerebral Palsy. Harvard Univ. London: Press, Cambridge (Mass.), Oxford University Press; 1959.  Back to cited text no. 4      
5.Henderson JL. Cerebral palsy in childhood and adolescence. Edinburgh: Livingstone; 1961.  Back to cited text no. 5      
6.Ingram TS. Paediatric aspects of cerebral palsy. Edinburgh: Livingstone; 1964a.  Back to cited text no. 6      
7.Laget P, Gagnard L, Ostre C, d'Allest AM. Visual evoked potentials in children with non-hemiplegic cerebral palsy. Adv Neurol 1982;32:97-107.  Back to cited text no. 7      
8.Ku΃ak W, Sobaniec W, Kuzia JS, Boζkowski L. Neurophysiologic and neuroimaging studies of brain plasticity in children with spastic cerebral palsy. Exp Neurol 2006;198:4-11.  Back to cited text no. 8      
9.Ku΃ak W, Sobaniec W, Boζkowski L, So΃owiej E, Smigielska-Kuzia J, Artemowicz B, et al . Neurophysiologic studies of brain plasticity in children with cerebral palsy. Rocz Akad Med Bialymst 2005;50:74-7.  Back to cited text no. 9      
10.Vargiami E, Zafeiriou DI, Kozeis N, Ververi A, Kontopoulos E, Mavromatis I, et al. Flash VEP findings in children with bilateral spastic cerebral palsy: Correlation with clinicoradiological parameters. J Pediatr Neurol 2008;6:329-39.   Back to cited text no. 10      
11.Breakey AS. Ocular findings in cerebral palsy. AMA Arch Ophthalmol 1955;53:852-6.  Back to cited text no. 11      
12.Altman HE, Hiatt RL, Deweese MW. Ocular findings in cerebral palsy. South Med J 1966;59:101-8.  Back to cited text no. 12      
13.Black P. Visual disorders associated with cerebral palsy. Br J Ophthalmol 1982;66:46-52.  Back to cited text no. 13      
14.Scheiman MM. Optometric findings in children with cerebral palsy. Am J Optom Physiol Opt 1984;61:321-3.  Back to cited text no. 14      
15.Erkkilδ H, Lindberg L, Kallio AK. Strabismus in children with cerebral palsy. Acta Ophthalmol Scand 1996;74:636-8.  Back to cited text no. 15      
16.Pennefather PM, Tin W. Ocular abnormalities associated with cerebral palsy after preterm birth. Eye 2000;14:78-81.  Back to cited text no. 16      
17.Guzzetta A, Mercuri E, Cioni G. Visual disorders in children with brain lesions: 2, Visual impairment associated with cerebral palsy. Eur J Paediatr Neurol 2001;5:115-9.  Back to cited text no. 17      
18.Atchaneeyasakul LO, Trinavarat A, Wanumkarng N, Samsen P, Thanasombatsakul N. Value of electrodiagnostic assessment in nonsyndromic microcephaly. Eur J Ophthalmol 2003;13:702-9.  Back to cited text no. 18      
19.Muttitt SC, Taylor MJ, Kobayashi JS, MacMillan L, Whyte HE. Serial visual evoked potentials and outcome in term birth asphyxia. Pediatr Neurol 1991;7:86-90.   Back to cited text no. 19      
20.Zafeiriou DI, Andreou A, Karasavidou K. Utility of brainstem auditory evoked potentials in children with spastic cerebral palsy. Acta Paediatr 2000;89:194-7.  Back to cited text no. 20      


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]


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