Moyamoya disease concurrent with Graves' disease treated by direct bypass: clinical features and treatment strategies

Moyamoya disease (MMD) concurrent with Graves' disease (GD) is rare. There is no guideline about optimizing thyroid hormones and the appropriate timing of surgical treatment for MMD with GD. We encountered eight patients with MMD and GD presenting with cerebral ischemia who were treated by direct bypass. Thyroid hormones [free thyroxin (fT(4)) and free triiodothyronine (fT(3))], thyroid-stimulating hormone (TSH), and TSH receptor antibody (TRAb) were measured sequentially. After thyrotoxic conditions were medically optimized, revascularization surgery was performed by superficial temporal artery-middle cerebral artery (STA-MCA) double bypass in all cases. Clinical outcomes were estimated by modified Rankin scale (mRS) at discharge and 3 months after surgery. In six patients with thyrotoxicosis, the fT(4), fT(3), and TRAb (range) at the onset of cerebral ischemia were 4.81-10.30 pg/ml, 13.08-31.90 pg/ml, and 3.5-83.8 IU/l, respectively. At surgery, mean (range) fT(3) and fT(4) were optimized to 3.02 (1.01-4.87) pg/ml and 1.09 (0.41-1.68) ng/dl, respectively. In the thyrotoxic cases, it took 70-310 days (mean, 142 days) to optimize thyroid hormones before surgery. There was no neurological aggravation after surgery, and outcome was excellent at 3 months with mRS scores a parts per thousand currency sign2 in all cases. For MMD concurrent with GD, optimizing thyroid hormones followed by STA-MCA double bypass was successful to prevent cerebral ischemic events.