Hemifacial atrophy is thinning of subcutaneous tissues on one side of the face; it may also involve muscle and bone (causing enophthalmos), and sometimes brain, in which case neurological features (hemiparesis, hemianopia, focal seizures, cognitive impairment) may also be present.
The clinical heterogeneity of hemifacial atrophy probably reflects pathogenetic heterogeneity. The syndrome, sometimes referred to as Parry-Romberg syndrome, may result from maldevelopment of autonomic innervation or vascular supply, or as an acquired feature following trauma, or a consequence of linear scleroderma (morphea), in which case a coup de sabre may be seen.
Larner AJ. Neurological contributions of Caleb Hillier Parry. Advances in Clinical Neuroscience & Rehabilitation 2004; 4(3): 38-39 Larner AJ, Bennison DP. Some observations on the aetiology of hemifacial atrophy ("Parry-Romberg syndrome"). Journal of Neurology, Neurosurgery and Psychiatry 1993; 56: 1035-1036