Relationship Between Visual Pathway Abnormality and VEP Responses in Term and Preterm Infants


SCIENTIFIC POSTER

Relationship Between Visual Pathway Abnormality and VEP Responses in Term and Preterm Infants by Hee Seung Chin, Soo Jeong Han, South Korea


ABSTRACT

Background:

The visual evoked potential (VEP) in infants is used as a noninvasive method helpful in diagnosing the diseases of optic chiasm and optic nerve. Especially, preterm infant is vulnerable to brain injury induced by hypoxia or ischemia, therefore VEP study is often used as a screening test.

The purpose of this study is to evaluate the relationship between the visual pathway abnormality and VEP responses in term and preterm infants.

Method:

Flash VEP studies of 58 term and preterm infants requested at the department of ophthalmology and rehabilitation medicine center were analyzed retrospectively. On the basis of findings of brain CT and MR images, infants were divided into two groups, one has the lesion in visual pathway (retina, optic nerve, optic chiasm, lateral geniculate body, optic radiation and visual cortex) and the other has no lesion. The results of VEP studies were scored ‘0 score’ in case of showing normal P2 latency, normal waveform and good reproducibility, and ‘1 score’ in case of showing attenuated waveform or delayed P2 latency, and ‘2 score’ in case of no response. The method of statistics used Mann-Whitney U test to compare term and preterm VEP response.

Results:

Term infants younger than 5 years were 42 (boys: 32, girls: 10, mean age: 61.27±516.4 weeks, age range: 2 days~5 years), and preterm infants younger than 38 weeks were 16 (boys: 7, girls: 9, mean gestational age: 41.75±9.7 weeks, range of gestational age at study: 33~66 weeks, range of gestational age at birth: 25~38 weeks). Twelve term infants out of 42 and 6 preterm infants out of 16 had lesion in visual pathway (Table 1). In preterm infants, there was no significant difference in VEP scores between preterm infants with visual pathway abnormality and without abnormality (right p=0.52, left p=0.62). However, term infants with visual pathway abnormality showed significantly higher VEP score than term infants without visual pathway abnormality (right p=0.00, left: p=0.00). In case of infants with visual pathway abnormality, term infants showed significantly lower score than the preterm infants in right VEP study (right p=0.05, left p=0.27). Also, in case there was no visual pathway abnormality, the term infants showed significantly lower score than the premature infants in both left and right.

Conclusion:

In term infants, it can show more severe abnormal results in VEP study with visual pathway abnormality than without visual pathway abnormality. However, preterm infants might show severe abnormality regardless of whether visual pathway is abnormal or not. Besides, regardless of visual pathway abnormality, preterm infants can show more severe abnormality in VEP study than term infants.

In conclusion, even if preterm infants have no visual pathway abnormality, follow up VEP study should be more needed than term infants, associated with brain immaturity of preterm infants.


CONTACT DETAILS

 

Hee Seung Chin
Incheon, South Korea
Email : hschin@inha.ac.kr
Cell Phone: +821038856506
Work Phone: +82328902400