Serial, Visually-Evoked Potentials for the Assessment of Visual Function in Patients with Craniosynostosis

Abstract

This study aimed to evaluate the effect of craniofacial surgical intervention on the visual pathway’s function by comparing pre- to post-operative patterned, visually-evoked potentials (pVEP). A retrospective review was conducted on craniosynostosis patients who had pre- and post-craniofacial surgery pVEP testing. The pVEP measured grade in terms of amplitude latency and morphology of the waveforms. The pre- and post-operative results were compared. The study identified 63 patients (mean age at preoperative pVEP of 16.9 months). Preoperatively, 33 patients (52.4%) had abnormal pVEP. Nine patients had evidence of intracranial hypertension, and of those, eight (88.9%) had abnormal pVEP. Within 6 months postoperatively, 24 of 33 patients (72.7%) with abnormal preoperative pVEP developed normal postoperative pVEP, while all 30 patients with normal preoperative VEP maintained their normal results postoperatively. Significant improvements in pVEP latency in patients with broad or delayed latency waveforms was evident for subjects with preoperative grades 2–4 (grade 2, p = 0.015; grade 3, p = 0.029; grade 4; p = 0.007), while significant postoperative increase in amplitude was significant for patients with abnormally low amplitude grade 3 and 5 waveforms (grade 3, p = 0.011; grade 5, p = 0.029). Serial pVEP testing represents a useful tool for the early detection of visual pathway dysfunction and follow up visual pathway function in craniosynostosis. Surgical intervention for craniosynostosis can result in the reversal of preoperative pVEP abnormalities seen in these patients, resulting in the normalization of the pVEP waveform, amplitude and latency, depending on the preoperative pVEP abnormality.

Clinical electrophysiology of the optic nerve and retinal ganglion cells

“…Nevertheless, an abnormal PR-VEP at baseline does predict worse visual outcome and shares a close relationship with visual field abnormalities [ 241 , 242 ]. Other studies have demonstrated a high prevalence of PR-VEP abnormality in paediatric craniosynostosis [ 243 ], including the use of serial PR-VEPs in longitudinal monitoring of rICP, some demonstrating a 71% sensitivity and 100% specificity for rICP [ 244 – 246 ]. These were detected through longitudinal study of PR-VEPs recorded to a range of spatial frequencies, which improves the sensitivity of detecting rICP in craniosynostosis and IIH [ 247 ].…”

Electrophysiological Study of Visual Pathways in Nevoid Basal Cell Carcinoma Syndrome Patients

“…Such anomalies could cause impaired functioning of the visual apparatus, as they have been described in the literature for other genetic conditions linked to cranial and cerebral malformations. 32,33 The cause could also be traced to an altered path and/or an extension of the optical pathways beyond the norm. Or the craniofacial malformations could be the primary cause responsible for abnormal ganglion-cell axon myelination, or the lack of integrity of corpus callosum necessary for the development and plasticity of the visual system.…”

“…Such anomalies could cause impaired functioning of the visual apparatus, as they have been described in the literature for other genetic conditions linked to cranial and cerebral malformations. 32 , 33 …”

Update in Management of Craniosynostosis

“…Visual-evoked potentials testing is not a direct measurement of intracranial pressure, but rather measures the integrity of visual pathways, which are affected by intracranial pressure. 49 Early research demonstrated that increased prolongation of the N2 wave latency period correlates with elevated intracranial pressure. 50 A recent study 51 of 13 patients with late presenting craniosynostosis (average age, 5 years) demonstrated abnormal visual-evoked potentials patterns on serial testing in 71.4 percent of patients with confirmed intracranial hypertension.…”