Parasagittal vertex clots on head CT in infants with subdural hemorrhage as a predictor for abusive head trauma

Background Abusive head trauma (AHT) is the most common cause of subdural hemorrhage (SDH) in infants younger than 12 months old. Clot formation in the parasagittal vertex seen on imaging has been associated with SDH due to AHT. There have been very few studies regarding these findings; to our knowledge, no studies including controls have been performed. Objective To describe parasagittal vertex clots on head computed tomography (CT) in infants with SDH and AHT compared to patients with SDH and accidental trauma, and to evaluate for parasagittal vertex clots in the absence of SDH in the setting of known accidental head trauma. Materials and methods All infants younger than 12 months old with SDH present on CT scan were retrospectively identified from 2004 to 2014. Blinded, independent review of all CT scans for clot formation at the parasagittal vertex was performed by a pediatric neuroradiologist. Results Ninety-nine patients were eligible for analysis. Mean age was 4 months. Fifty-seven (57.6%) were male. Fifty-five (55.6%) patients were identified as having AHT and 22 (22.2%) had accidental trauma. Forty-five (81.2%) patients with AHT had parasagittal vertex clots present on CT scan compared to 8 (36.4%) patients with accidental trauma. Compared to patients without parasagittal vertex clots, those with parasagittal vertex clots were more likely to have AHT (66.2% vs. 32.3%, P =0.001), no known mechanism of injury (69.1% vs. 32.3%, P =0.015), retinal hemorrhage (75% vs. 35.5%, P =0.002) and hypoxic-ischemic changes (25% vs. 0%, P =0.002). Patients with parasagittal vertex clots have eight times the odds of AHT compared to patients without parasagittal vertex clots. Age-matched control patients who underwent head CT scan due to a history of accidental head injury without SDH were identified ( n =87); no patient in the control group had parasagittal vertex clots. Conclusion The finding of parasagittal vertex clots on CT scans should raise suspicion for abuse and prompt further investigation, especially in the setting of no known, uncertain or inconsistent mechanism of injury.