Date of Award
Medical Doctor (MD)
John A. Persing
Craniosynostosis is a pathological condition in which one or more cranial sutures are prematurely fused. The relationship between nonsyndromic, single-suture craniosynostosis and future neurocognitive ability is unclear, with several studies reporting neurological deficits in areas of learning, language development, and behavior. Surgery is performed to relieve restrictive forces on the underlying brain. This is thought to attenuate the neural deficit in single suture synostosis, however the degree to which it may do so is unknown. This knowledge is essential to guide future surgical treatment recommendations.
Currently, there is a lack of standardized neurodevelopmental infant tests that can identify patients at risk for neurological deficit. However, electrophysiological studies utilizing event-related potentials (ERPs) in infants have been promising. ERPs are cerebral voltage changes observed on continuous electroencephalogram that reflect the brain’s electrical response to external stimuli. Infant ERPs in response to auditory speech stimuli have been shown to have high correlation with language and reading tasks during childhood. Specifically, studies have found that abnormal ERPs to speech
sounds at birth could predict the reading performance and risk of dyslexia in children up to eight years later.
The present study aims to evaluate auditory processing in patients with single suture craniosynostosis at two time points: before and after surgery. The study also followed normally developing matched control infants, to discern the neurological risk carried by different types of craniosynostosis and the effect of surgery.
Forty-eight infants underwent evaluations of auditory processing: 16 patients with metopic suture craniosynostosis (categorized based on a severity index), 8 with sagittal suture craniosynostosis, 2 patients with metopic ridging, and 22 normally developing control infants. Brain activity was recorded by electroencephalography (EEG) while the participants passively listened to auditory presentations of speech syllables. EEG data over the frontal and temporal-parietal regions were analyzed to extract event related potentials (ERPs) evoked by the speech sounds.
Patients with severe metopic synostosis demonstrated significantly attenuated ERP responses in the left frontal scalp region overlying the left frontal lobe compared to controls (p < 0.05). Patients with moderately severe metopic synostosis patients did not show significantly different language processing compared to the control infants nor the severe MSO patients. Untreated SS patients had a trend toward attenuated N450 components in the left temporal-parietal region compared to controls (p=0.06). Presurgery patients also had exaggerated P150 components compared to controls with trending toward significance (p=0.06) in this region. No difference was found between the two groups after treatment in this region of the brain(p=0.47 and p=0.13 for N450
and P150, respectively).
Results suggest that untreated severe MSO is associated with reduced language response in the frontal cortex. Less severe (moderate) forms are indeterminate, and mild forms do not show calculable irregularity by the ERP method of analysis. Infants with untreated SS are trending towards abnormal language processing relative to control subjects. However, SS patients may have more normalized cortical processing as early as 6 months following surgery.
Yang, Jenny, "Electrophysiology Reveals Changes In Neurological Function After Corrective Surgery For Craniosynostosis" (2016). Yale Medicine Thesis Digital Library. 2097.