The cause, he found, was that the bone was produced faster than the body broke it down, making it much thicker as the patient got older.
The first symptoms experienced by the affected were often deafness and paralysis of the face, caused by the growing bone pinching the nerves.
There have been attempts to relieve a patient suffering from van Buchem disease: "A large bilateral frontoparietal craniotomy and decompression of the foramen magnum resulted in almost complete relief of his symptoms.
"[2] There are fewer than 30 confirmed patients known to suffer from this disease; 22 of them are from the Netherlands and 14 are from Urk specifically.
[4] However, the residents still remained a closed community, and the centuries of isolation have led to a consequence in almost exclusive intermarriage.