ABSTRACT NUMBER: ESOC2026A2389 MULTIPLE BRAINSTEM SYNDROMES FOLLOWING HAEMORRHAGIC STROKE: A NEUROANATOMICAL PUZZLE

Abstract Background Haemorrhagic stroke accounts for 15% of all strokes, with higher prevalence (30%) in low-income countries. Its most common aetiology is sporadic small vessel disease, typically affecting deep brain structures. This case illustrates an unusual presentation as multiple brainstem syndromes. Case Presentation A 51-year-old Cape Verdean woman with hypertension and obesity presented with acute left eyelid drop and right-sided weakness. Blood pressure on admission was 220/110 mmHg. Neurological examination revealed complete eyelid ptosis, fixed mydriasis, and complete ophthalmoplegia of the left eye, with limited supraduction and adduction of the right eye, absent convergence, and impairment of both vertical and horizontal vestibulo-ocular reflexes, as well as right-sided central facial paresis, spastic hemiparesis, Babinski sign, inexhaustible ankle clonus, and cerebellar hemiataxia. Cranial CT demonstrated left thalamo-mesencephalic haemorrhage, and the CT-angiography excluded vascular malformations. Brain MRI confirmed intra-axial mesencephalic and upper pontine hematoma extending to the left subthalamic region with associated oedema. Hypertension was controlled and the patient was discharged with partially recovered oculomotor limitations, but able to walk with a cane. Clinical Diagnosis The constellation of findings was consistent with both vertical and horizontal one-and-a-half syndrome (involvement of both the mesencephalic conjugate vertical gaze pathways and the pontine conjugate horizontal gaze pathways), and Benedikt syndrome (left third nerve palsy with contralateral hemiparesis and cerebellar hemiataxia). Conclusions This case exemplifies the clinical and semiological complexity of brainstem haemorrhages presenting with multiple brainstem syndromes, affecting different anatomical levels. Meticulous neurological examination is essential for the accurate interpretation of such complex brainstem presentations. Conflict of interest João Oliveira: Nothing to disclose; Liliana Pereira: Nothing to disclose; Miguel Grunho: Nothing to disclose; Cláudia Silva: Nothing to disclose.