Case Report: Probable paroxysmal sympathetic hyperactivity during vascular and postoperative critical illness with bilateral white matter abnormalities

Background Recognition of paroxysmal sympathetic hyperactivity (PSH) during vascular and postoperative critical illness is complicated by overlapping infection and seizure features. Case presentation A 37-year-old man developed encephalopathy and rigidity after extensive arterial thrombosis, thrombectomy, and suspected postoperative sepsis. January 2025 observations documented recurrent, transient, simultaneous tachycardia, increased blood pressure, tachypnea, fever, sweating, and abnormal posturing. The treating team diagnosed PSH, which remained among the February 12 transfer diagnoses. Brain magnetic resonance images dated February 20, 2025, showed symmetric bilateral periventricular and deep white matter abnormalities without definite diffusion restriction. Targeted serum and cerebrospinal fluid antibody testing was negative. A clinician-completed PSH Assessment Measure (PSH-AM) recorded 24 points; conservative reassessment retained recorded severity grades and yielded 20, still classified as probable PSH. Paroxysms persisted as documented infection improved, decreased during multimodal treatment, and recurred during combined medication reduction. At the February 12 intrahospital rehabilitation transfer, communication and tone had improved, but contractures and severe limb motor impairment persisted. Cerebral etiology remained uncertain, and seizures could not be excluded because electroencephalographic event capture was unavailable. Conclusion The case highlights serial clinical recognition of probable PSH during vascular and postoperative critical illness, alongside infection assessment and attention to persistent rehabilitation needs.