What Is Hyperostosis Frontalis Interna?

Hyperostosis frontalis interna is a medical condition characterized by the inner side of the skull's frontal bone thickening. The condition is not clinically significant in that the growth of the bone is not malignant. Often, the patient may go through his or her entire life not even knowing about it. This overgrowth of bone is much more common in women than in men. It also seems to be significantly more prevalent in older women nearing menopause.

The thickened bone, while always affecting the frontal bones, can sometimes involve the parietal bones of the skull as well. The thickened area is usually bilateral and symmetrical. It can be either focal, affecting only a certain portion, or diffuse, affecting a large part, if not all, of the bone. The overgrown portions themselves can be somewhat flat and even, or they may be nodular in appearance.

Symptoms of this condition are quite general in the sense that they can also occur with a number of other conditions. They can include a frontal headache, mental impairment, and depression. Weakness, obesity, and fatigue are also common, as are vertigo and facial palsy.

Due to these symptoms being somewhat generalized, a differential diagnosis must be made. Paget's disease, fibrous dysplasia, and acromegaly are all conditions with similar symptoms. The only diagnostic tool in determining the presence of hyperostosis frontalis interna is through a radiograph image that clearly shows the thickened bone. Often, the disease is accidentally found when the patient is being treated for another condition. Due to this, it is unclear how many people actually suffer from this overgrowth of bone.

Hyperostosis frontalis interna can, in some cases, be part of a more complex syndrome. Called Morgani syndrome, this condition is an endocrine pathology where the hyperostosis frontalis interna occurs in conjunction with diabetes and hyperparathyroidism. Symptoms of this condition include hirsutism, menstral problems, and seizures.

The cause of hyperostosis frontalis interna is unknown; however, as it seems to affect mostly older women nearing menopause, hormones, namely estrogen, may be involved. As the thickening of the bone is benign and not harmful to the patient, there is no treatment for hyperostosis frontalis interna. Rather, the symptoms are considered to be a separate issue and treated accordingly. The phenomenon is not life threatening, and people who suffer from it lead normal lives with the same life expectancy as those without the condition.