February 17, 2003

Dear Cystinosis Research Family,

I wish to bring to your attention the occurrence of a medical complication which we have noticed in several patients with nephropathic cystinosis. The complication is called pseudotumor cerebri, or PTC.

PTC is a condition in which the pressure inside the head is increased, but not because of a tumor. Rather, the fluid surrounding the brain has high pressure. That fluid is called cerebrospinal fluid, and the increased pressure can be due to overproduction of the fluid or decreased removal of the fluid. The symptoms are headache, nausea, and vomiting. In infants and children, irritability, apathy, lethargy, and dizziness can occur. The signs are an abnormal elevation of the optic nerve on examination of the retina of the eye, and increased fluid pressure when a spinal tap is performed. The MRI of the brain is normal in cases of PTC. The signs and symptoms of PTC can come and go. Therapy includes an oral diuretic medication, which generally resolves the problem within months.

Of the approximately 100 cystinosis patients seen at the NIH Clinical Center in the past 10 years, two were diagnosed with PTC during visits to the NIH Ophthalmology clinic. Four other NIH patients with cystinosis were diagnosed with PTC at other institutions.

PTC is thought to occur because of a combination of risk factors. The risk factor in the cases we have seen could be cystinosis itself. However, the drug cysteamine could also be involved, and so could certain hidden genetic conditions. I would emphasize that cystinosis patients should continue to diligently take the dose of cysteamine prescribed, because there is no evidence that PTC is related to cysteamine therapy, and the benefits of cysteamine treatment outweigh the risk of PTC even if there is a relationship between the two. NIH physicians are beginning a study of possible genetic causes of PTC in cystinosis patients.

In summary, PTC is an unusual, treatable complication associated with cystinosis. If you have one of the symptoms noted above, you might wish to show this letter to your physician so that your retina can be briefly examined.

If you have any questions concerning PTC, or if you have not been seen at the NIH Clinical Center in the past 2-3 years, please call my research nurse, Joan (Ziggy) Balog, at 301-496-5422 or jbalog@nhgri.nih.gov.

Sincerely,

William A. Gahl, MD, PhD

National Institutes of Health
Medical Genetics Branch
Building 10, Room 10C 103
10 Center Dr. MSC 1852
Bethesda, MD 20892
Phone: (301) 402-2739
Fax: (301) 496-2740
Email: bgahl@helix.nih.gov