Incidence of Hyperostosis Frontalis Interna in Patients at a General Hospital and at a Mental Hospital.

Hyperostosis frontalis interna is a curious abnormality of the inner tables of the frontal bones of the skull, said to have been first described by Morgagni in 1761. It consists of aggregations of smooth, rounded enostoses which are covered by dura mater and project into the cranial cavity. Most are about 0 5 to 1 0 cm. in diameter at their bases and attain a similar height. The enostoses do not encroach upon the midline nor, as a rule, extend posteriorly beyond the coronal suture (Figs. 1 and 2). Despite a voluminous literature very little is known about hyperostosis frontalis interna. Thus its mode of formation and growth is unknown, the incidence among the general population is uncertain, and the question as to whether it is merely an anatomical anomaly or a pathological lesion remains unanswered. The striking appearances of hyperostosis frontalis intema, first at necropsies and later in radiographs of the skull, naturally led to attempts to link it with symptoms which have coexisted in affected individuals. Two syndromes have been described in association with it, namely, Morgagni's syndrome, sponsored by Henschen (1949), consisting of hyperostosis frontalis interna, virilism, and obesity in women, and the Stewart-Morel syndrome (Stewart, 1928; Morel, 1930), comprising hyperostosis frontalis intema, obesity, and neuropsychiatric disorders. But neither of these syndromes has been generally accepted, nor has its designation as a 'metabolic craniopathy' by Grollman and Rousseau (1944). We have been unable to find recorded any radiological survey designed to seek or which shows the incidence of hyperostosis frontalis interna in the general population. Those reported have been concerned with the incidence in small selected groups of men or women or in the inmates of mental hospitals. The only information which emerges is that hyperostosis frontalis interna appears to be commoner in women than in men, and in elderly women than in younger. Caughey (1952) has also shown a high incidence in patients of both sexes suffering from dystrophia myotonica and Moore (1952) described its association with acromegaly. The main objects of this radiological survey were 171 to determine the incidence of hyperostosis frontalis interna among patients at a general hospital and at a mental hospital and to seek confirmation that it was commoner in women as age advanced. A subsidiary object was to obtain evidence as to whether hyper-