We evaluated and analyzed the effect of superficial temporal to middle cerebral artery (STA-MCA) bypass for ischemic cerebrovascular diseases (CVDs) on pure motor function using motor activation single photon emission computed tomography (SPECT), and we also compared this effect with the resting cerebral blood flow and reserved capacity.
Motor activation SPECT studies were carried out on 22 cases with STA-MCA bypass performed for symptomatic ischemic CVDs. All motor activation SPECT studies using the finger opposition task on the affected side were performed before bypass, at 1 month, and 3 months after the bypass. Visual inspection was used to determine whether the result of the motor activation SPECT was as negative or positive. The activated region was detected anatomically precisely by superimposing the SPECT images on the MR images. Before we started this study, we performed the same examination on 11 normal control cases. Among the 11 cases, 10 (91%) showed the activated area on the sensorimotor cortex after the finger opposition task.
Before bypass, the resting SPECT studies revealed reduction of cerebral blood flow (CBF) on the affected side in all 22 cases. All 22 cases also showed a disturbed response to acetazolamide (ACZ). Nine cases were positive in the motor activation SPECT study. One month after bypass, the resting CBF increased in 11 cases. Seven showed preoperative positive motor activation. Fifteen cases were positive in the motor activation SPECT. Three months after bypass, 20 cases showed improvement in the resting CBF, and 19 cases were positive in the motor activation SPECT. Among these, 10 cases were negative in the preoperative motor activation SPECT. At one month after surgery, ACZ activation SEPCT was performed in 12 cases. Five showed improvement of the response to ACZ. At 3 months after surgery, 8 of 12 cases treated with ACZ activation SPECT showed improved response to ACZ. In most of the cases, improved response to ACZ could be seen after response to motor activation improved.
STA-MCA bypass is useful not only for resting CBF but also for pure motor function based on motor activation SPECT. We concluded from the preoperative motor activation study that cases with preoperative positive motor activation could attain the effect of bypass earlier than preoperative negative cases. Improvement of the motor activation response could be seen before improvement of the ACZ response in most cases.
