Unilateral atrophy of facial tissues, including muscles, bones and skin.

A rare genetic vascular anomaly characterized by the presence of angiomatous lesions affecting the skin, brain, and spinal cord. Lesions of the central nervous system have a marked tendency to bleed. There have been no further descriptions in the literature since 1988.

PHACE is an acronym for a neurocutaneous syndrome encompassing the following features: posterior fossa brain malformations, hemangiomas of the face (large or complex), arterial anomalies, cardiac anomalies, and eye abnormalities. The association is referred to as PHACES when ventral developmental defects, such as sternal clefting or supraumbilical raphe, are present (summary by Bracken et al., 2011).

Primary basilar impression of the skull is a developmental defect of the cranium in which there is invagination of the foramen magnum upward into the posterior cranial fossa. Basilar impression is often associated with other malformations of the notochord and craniovertebral junction, such as occipitalization of the atlas, Klippel-Feil anomaly (see 118100), Chiari type I malformation (118420), and syringomyelia (186700) (Paradis and Sax, 1972; Bhangoo and Crockard, 1999). Secondary basilar impression occurs as a result of generalized skeletal diseases, including hyperparathyroidism (see 145000), Paget disease (see 167250), and osteogenesis imperfecta (see, e.g., 166200). Platybasia refers to a skull base with an abnormally obtuse angle between the planes of the clivus and the anterior fossa. Platybasia may occur in basilar impression, but it is not of medical significance on its own (Bhangoo and Crockard, 1999). Historically, basilar impression was defined radiologically by numerous parameters, including the lines defined by Chamberlain (1939), McGregor (1948), and Fischgold and Metzger (1952), and the angle defined by Bull et al. (1955).

Syringomyelia (Greek: 'syrinx,' pipe, and 'myelos,' marrow) is a tubular cavity in the spinal cord. It can occur sporadically in association with spinal cord tumors, inflammatory arachnoiditis, or posttraumatically. It is rarely idiopathic (less than 1% of cases). The vast majority of cases of syringomyelia are cervical, noncommunicating, and associated with an abnormality at the foramen magnum, particularly the Chiari malformation type I (CM1; 118420), as well as basilar impression (109500) and Dandy-Walker malformation (220200) (Speer et al., 2003; Levine, 2004); these cases have shown familial segregation. The form of syringomyelia discussed here is 'noncommunicating' with the fourth ventricle, but may communicate with the subarachnoid space. In contrast, 'communicating' syringomyelia, or 'hydromelia,' opens rostrally into the fourth ventricle and almost always occurs in children with hydrocephalus, Chiari malformation type II (CM2; 207950), and spina bifida (see 182940) (Levine, 2004).