Closed Meningo(encephalo)cele: a new feature in Hunter syndrome

Abstract

Background and purpose: Hunter syndrome (MPS type II) is a rare X-linked recessive disease caused by lysosomal enzyme iduronate-2-sulfatase deficiency, characterized by frequent and variable brain and skull involvement. Our objective was determine the frequency of closed cephaloceles in a large cohort of subjects affected with Hunter syndrome and to investigate possible correlations with clinical and neuroradiologic findings.

Materials and methods: Brain MR imaging of 33 patients (32 males and 1 female, age range 2.5-30.8 years, mean age 10.4 years) affected with Hunter syndrome were retrospectively evaluated. Eleven (age range 3.6-30.8 years; mean age 15.1) presented with an "attenuated" phenotype, while 22 (age range 2.5-19.1 years; mean age 8.2) had a "severe" phenotype.

Results: A closed cephalocele was detected in 9/33 patients (27%) at the level of anterior and middle fossa in 6 and 3 cases, respectively; 6/9 subjects were affected with the attenuated phenotype and 1/9 suffered from epilepsy. Closed cephaloceles did not show a significant association with other brain and spine MR imaging features of Hunter disease, such as enlargement of perivascular spaces, cisterna magna, pituitary sella, ventricles and subarachnoid spaces, craniosynostosis, dens hypoplasia, white matter abnormalities, spinal stenosis due to periodontoid cap, platyspondylia, or intervertebral disk anomalies.

Conclusions: Closed cephaloceles are frequent in Hunter syndrome and should be considered a neuroradiologic feature of this disease.

Fig 1.

Eight-year-old patient with Hunter syndrome, severe phenotype. A and B, Coronal fluid attenuated inversion recovery images at the level of the anterior portion of the middle cranial fossa disclosing a closed meningoencephalocele on the left side, magnification of A, showing the meningeal pouch with eccentric brain parenchymal herniation (curved arrow); a thin hypointense rim borders the pouch. D, CT coronal image obtained with multiplanar reconstruction technique at the level of C, showing the bone nature (white arrows) of the hypointense rim. E, Axial T2-weighted image revealing a multiloculated large pouch. F, CT volume rendering technique 3D-reconstruction depicting the inner aspect of the bone abnormality (black arrows).

Fig 2.

Twenty-year-old patient with Hunter syndrome, attenuated phenotype syndrome. A and C, 12-year-old patient with Hunter syndrome, attenuated phenotype A and B. Sagittal T1-weighted images showing the meningeal pouches at the level of the anterior cranial fossa, mainly filled by CSF (A) or brain parenchyma (B). C, Magnification of A, revealing the abnormal course of the olfactory tract and bulb (arrows) diving toward a depressed lamina cribrosa. D, CT sagittal image obtained with multiplanar reconstruction technique showing the presence of a bone pavement, with foramina for the phila olfactoria (white arrows).

Fig 3.

Thirteen-year-old patient with Hunter syndrome, severe phenotype A, Sagittal T2-weighted image showing severe brain atrophy, an enlarged pituitary sella, and a large irregular meningeal pouch at the level of the anterior cranial fossa. B, Magnification of A, showing the brain parenchymal eccentric herniation to the deepest part of the meningeal pouch (curved arrow); the dotted line represents the level of the anterior cranial fossa in normal subjects C, CT coronal image obtained with multiplanar reconstruction technique, revealing the bone defect (white arrows) reaching the middle turbinate on both sides.