Enlargement of the Internal Auditory Canal and Associated Posterior Fossa Anomalies in PHACES Association

Abstract

SUMMARY:We noted enlargement of the internal auditory canal in several of our patients with posterior fossa malformations, hemangiomas, arterial anomalies, cardiac defects, eye abnormalities, and sternal or supraumbilical defects (PHACES) association and hence evaluated children with PHACES for the presence of an enlarged internal auditory canal and potential associated findings, including infantile hemangioma within the internal auditory canal, to understand the genesis of this enlargement. We reviewed our records to identify children with PHACES association who had been evaluated with MR imaging at our institutions. Imaging was reviewed for abnormal enhancement in the internal auditory canal, internal auditory canal enlargement, cerebellar hypoplasia, prominence of the petrous ridge, and deformity of the calvarium. We raise the possibility of an association between enlargement of the internal auditory canal in PHACES and a generalized malformation of the posterior fossa with cerebellar and calvarial hypoplasia. ABBREVIATIONS:IAC ϭ internal auditory canal; PHACES ϭ posterior fossa malformations, hemangiomas, arterial anomalies, cardiac defects, eye abnormalities, and sternal or supraumbilical defects P osterior fossa malformations, hemangiomas, arterial anomalies, cardiac defects, eye abnormalities, and sternal or supraumbilical defects compose the PHACES association.1,2 The regional facial infantile hemangiomas of PHACES association are frequently associated with ipsilateral cerebellar hypoplasia and ipsilateral anomalies of the intracranial internal carotid artery. 3,4 More recently, attention has been drawn to the incidence of intracranial hemangiomas, especially in the internal auditory canal (IAC) and cerebellopontine angle cistern.5-8 The purpose of this study was to document the incidence and imaging appearance of anomalies of the IAC and the potential for associated posterior fossa anomalies in patients with PHACES association. CASE SERIESThe index patient was a 25-year-old woman who presented with chronic hearing loss and a history of a facial hemangioma in infancy. Initial temporal bone CT revealed a funnel-shaped configuration of the prominent left IAC, prominence of the left posterior petrous ridge, hypoplasia of the left occipital bone, and findings consistent with a persistent left stapedial artery (Fig 1). Subsequent MR imaging demonstrated left cerebellar hypoplasia, enlargement of the left IAC, and an asymmetrically prominent left retrocerebellar CSF space (Fig 2). No abnormal enhancement was observed in the IAC or posterior fossa.Subsequent review of clinical data bases at 2 institutions identified 44 patients (37 male, 7 female) diagnosed with PHACES association who underwent diagnostic MR imaging of the brain between 2003 and 2012. Institutional review board approval was obtained from the 2 participating institutions for this retrospective review. A neuroradiologist with 9 years of experience and a pediatric neuroradiologist with 20 years of experience performed a consensus review of MR imag...

Asymmetric Meckel Cave Enlargement: A Potential Marker of PHACES Syndrome

“…Judd et al 12 reported on the association between PHACES and intracranial hemangiomas. Most commonly described in the cerebellopontine angle or IAC, hemangiomas centered in or extending to Meckel cave both have been described in the literature 12,13 and noted in our series. One Metzler et al 13 similarly raised the possibility of a causal association between IAC hemangioma and IAC enlargement.…”

“…Most commonly described in the cerebellopontine angle or IAC, hemangiomas centered in or extending to Meckel cave both have been described in the literature 12,13 and noted in our series. One Metzler et al 13 similarly raised the possibility of a causal association between IAC hemangioma and IAC enlargement. This was based on the increased prevalence of IAC hemangiomas within the enlarged IACs in children when imaged at younger than 1 year of age, compared with children older than 1 year of age at initial imaging, in whom the hemangiomas were presumed to have previously involuted.…”

“…Meckel cave enlargement may therefore represent a component of skull base dysplasia secondary to a postzygotic mutation or early prenatal insult in this territory. A similar theory was advanced to explain the relatively high incidence of enlarged IACs seen in PHACES syndrome observed by Meltzer et al 13 Alternatively, unilateral enlargement of Meckel cave may be the result of direct expansion secondary to an extant or previously involuted Meckel cave hemangioma. Judd et al 12 reported on the association between PHACES and intracranial hemangiomas.…”

“…The finding was subsequently described in 2 additional case reports. 9,10 Unilateral Meckel cave enlargement is also demonstrated in Figs 6 and 7 in the text Vascular Lesions of the Head and Neck: Diagnosis and Management by Persky et al, 11 Figs 1 and 2 from the article by Judd et al, 12 and Fig 5 from the article by Meltzer et al 13 Furthermore, some authors have described an association of arachnoid cysts and PHACES, 1,2,6,8,12,14 and an asymmetric Meckel cave could conceivably be confused with a middle cranial fossa arachnoid cyst, as was the case in one of our patients (patient 21).…”

Congenital vascular anomalies: current perspectives on diagnosis, classification, and management

“…There is a high incidence of a funnel-shaped enlarged internal auditory canal, many of which have a hemangioma within their enlarged structure. 11,[27][28][29] Dandy-Walker malformation (which is characterized by vermian hypoplasia, cystic dilatation of the fourth ventricle, and an enlarged posterior fossa with torcular-lambdoid inversion) is the most common posterior fossa malformation associated with PHACES syndrome. Large cervicofacial hemangiomas are the hallmarks of PHACES, classically with a segmental distribution.…”