Endoscopically Treated Subacute Subdural Hematoma Presenting Postoperative Cerebral Hyperperfusion Syndrome: Chronological Changes of Cerebral Blood Flow on Arterial Spin Labeling and Subcortical Low Intensity on Fluid-attenuated Inversion Recovery Images

Subacute subdural hematoma (SASDH) is a neurotraumatic entity. There are few reports of chronological changes of cerebral blood flow (CBF) on arterial spin labeling (ASL) and subcortical low intensity (SCLI) on fluid-attenuated inversion recovery (FLAIR) images of magnetic resonance imaging (MRI) observations from the injury onset, deterioration, to post-surgery. We reported a SASDH patient presenting postoperative cerebral hyperperfusion (CHP) syndrome with chronological changes of those findings. An 85-year-old woman fell and presented right ASDH. She was treated conservatively due to no neurological deficits. On day 3, ASL image revealed increased CBF against brain compression. On day 7, the CBF was normalized on ASL image, but SCLI was confirmed. On day 14, SCLI was strengthened. Then she developed left hemiparesis due to brain compression by SASDH. Considering age and comorbidities, we performed endoscopic hematoma removal under local anesthesia, and her neurological deficits improved after the surgery. On postoperative day 1, she newly presented left upper limb paresis. MRI revealed increased CBF and enhanced SCLI. We diagnosed CHP syndrome, and antihypertensive treatment improved the symptoms gradually. However, SCLI had been consistently observed, and CBF easily changed depending on the blood pressure, suggesting dysfunction of the CBF autoregulation. We showed the endoscopically treated SASDH patient with CBF’s chronological changes on ASL images and SCLI on FLAIR images. Long-time brain compression would lead to dysfunction of the CBF autoregulation, and we should be careful about CHP syndrome after the endoscopic surgery for SASDH.