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Neuroradiology Case of the Week

Case 219

Scott Cassar MD, and P-L Westesson, MD, PhD, DDS

Clinical Presentation: A one-month-old infant presented with trauma to the head and neck.  A CT of the head was requested for suspicion of a skull fracture.

Radiological Findings: There is a missing bone defect in the parietal lobes bilaterally, along the sagittal suture, 1.5cm superior to the posterior fontanelle.  It measures approximately 3cm in width and 1.5cm in height. There are no associated soft tissue or intracranial abnormalities.

Diagnosis: Early enlarged parietal foramina

Discussion: Small parietal foramina (1 to 2mm) are perforations in the skull near the parietal eminence for the passage of Santorini’s emissary veins. Either single or bilateral emissary foramina are considered normal variants and occur in at least 60% of the population. Enlarged parietal foramina (>5mm), however, rarely contain emissary veins and have a prevalence of 1:15,000 to 1:25,000. They are transmitted through autosomal dominant inheritance and are sometimes called “Catlin marks” as described by Goldsmith in 1922 when he identified enlarged parietal foramina in five generations of the Catlin family. Enlarged parietal foramina occur more frequently in males than in females and an increased incidence has been reported in patients with obesity, hypogenitalism, microphthalmos, and mental retardation.
     Enlarged parietal foramina develop as a single ossification defect involving both parietal bones (Fig. 1 ). Parasagittal islands of ossification cleave the defect into two foramina typically after birth. The edges of these bony defects have a characteristic beveled margin as ossification progresses with the inner table ahead of the outer table (Fig. 1 – arrow). Two large bony openings in the parietals remain which do not ossify with time. They appear as round or oval defects situated on each parietal bone approximately 1 cm from the midline and 2 to 3 cm superior to the lambdoid suture.
     Cranioplasty to correct persistent large foramina is occasionally performed in active young children and those at risk for injury (i.e., seizure disorder) to decrease the risk for potential intracranial injury. Cerebral vascular imaging is recommended before the procedure to detect venous developmental variations that occur with high frequency.

References:

1. Harwood-Nash, Derek C., and Fitz, Charles R. Neuroradiology in Infants and Children – Volume 1. The C.V. Mosby Company, St. Louis, MO. © 1976.
2. Kortesis B, Richards T, David L, Glazier S, Argenta L. Surgical management of foramina parietalia permagna. J Craniofac Surg. 2003 Jul;14(4):538-44. [Medline]
3. Reddy AT, Hedlund GL, Percy AK. Enlarged parietal foramina: association with cerebral venous and cortical anomalies. Neurology. 2000 Mar 14;54(5):1175-8. [Medline]