Alien Hand Syndrome Following Pontine Hemorrhage: A Case Report of Rare Mixed Phenomenology

Background and Clinical Significance: Alien hand syndrome (AHS) is a rare disorder of agency and complex motor control characterized by involuntary, apparently purposeful limb movements experienced as outside voluntary control. Pontine hemorrhage is an uncommon substrate, and its manifestations may overlap with sensory ataxia and other post-stroke movement disorders. Case Presentation: An 86-year-old right-handed man developed right-sided alien hand phenomena after a left pontine hemorrhage. Examination showed dysarthria, limited left gaze, diplopia, preserved muscle strength, marked right-sided proprioceptive impairment, a thalamic-hand-like posture, impaired spatial control, involuntary levitation, intermanual conflict, and purposeful-appearing rubbing movements when distracted. The diagnosis was based on loss of agency and autonomous limb behavior that could not be explained by sensory ataxia alone. Serial CT demonstrated an interval reduction in the size of the pontine hemorrhage; a representative thalamic level CT showed no evident thalamic hemorrhage or gross structural lesion, although a small CT occult ischemic lesion could not be excluded. Repeat MRI was not completed because of severe claustrophobia and anesthesia risk. EEG, formal neuropsychological testing, and standardized functional scales were unavailable. The NIHSS, assessed 15 days after admission to our hospital, was 6 points. No specific pharmacological treatment was initiated. Cognitive-behavioral rehabilitation was recommended, but transportation difficulties prevented regular attendance. Approximately three months after discharge, physician relatives reported resolution of abnormal movements and improved independent gait; no formal post-discharge examination was performed. Conclusions: Pontine hemorrhage may rarely be associated with mixed AHS phenomenology. Disruption of ascending proprioceptive and sensorimotor pathways is plausible, but the absence of advanced imaging and neurophysiological assessment precludes definitive anatomical or causal conclusions.