Morgagni-Stewart-Morel (MSM) syndrome is a disorder characterized by thickening of the frontal bone of the skull (hyperostosis frontalis interna), as well as obesity and excessive hair growth (hypertrichosis). Other signs and symptoms may include seizures, headaches, diabetes insipidus, and sex gland disturbances. The cause of Morgagni-Stewart-Morel syndrome is not fully understood. Some instances of dominant inheritance have been reported, but whether it is autosomal dominant or X-linked dominant is not known. Treatment may include medication for headaches and seizures and surgery to remove the excessive bone of the skull.

• Headache
• Vertigo
• Diabetes
• Excessive or unwanted hair growth (mainly in women)
• Menstrual disorders
• Nipple discharge (galactorrhea)
• Sex hormone imbalance
• Obesity
• Shorter than average height

Some people may also have the following signs and symptoms:

• Depression
• Irritability
• Fatigue
• Temporary paralysis on one side of the body
• Hearing impairment
• Paralysis of the cranial nerves
• Muscle weakness
• Seizures

While people with Morgagni-Stewart-Morel syndrome nearly always have hyperostosis frontalis interna, hyperostosis frontalis interna is usually an incidental finding on x-ray films, computed tomography, or magnetic resonance imaging of the head and by itself is not indicative of any disease.

The cause of Morgagni-Stewart-Morel syndrome and hyperostosis frontalis interna is unknown, although some have suggested that a hormonal imbalance due to genetic and environmental factors may be the cause of many of the symptoms of the syndrome.

The diagnosis of Morgagni-Stewart-Morel syndrome is based upon a radiological finding of hyperostosis frontalis interna, as well as a combination of clinical features including obesity, virulism (a female disorder in which there is development of secondary male sexual characteristics like growth of facial and body hair), possible mental disturbance, and other findings.

Seizures and headaches that may be associated with hyperostosis frontalis interna (HFI) are typically treated with standard medications.

In one journal article, the authors discuss a person with Morgagni-Stewart-Morel syndrome who reportedly had violent headaches. Surgery was performed to remove the hypertrophic frontal bone on the patient. He then had dura and bone reconstruction. The authors reported that the headaches stopped immediately after the operation.

Another article described a patient with HFI and intracranial hypertension (increased pressure inside the skull and brain). The authors reported good results with a craniotomy (a surgical operation in which a bone flap is temporarily removed from the skull to access the brain) performed to decrease the intracranial pressure.