Abstract Introduction Posterior reversible encephalopathy syndrome (PRES) and vertebrobasilar dolichoectasia compressing medulla are individually rare entities, with incidences of approximately 2.7 per 100,000 and only a few reported cases respectively. We report a unique case with diagnostic overlap between atypical PRES and dolichoectasia causing obstructive hydrocephalus at the level of the medulla, highlighting an unusual intersection of two uncommon conditions. Case Report A 42-year-old woman with a history of Attention deficit hyperactive disorder, depression, chronic neck pain, and tobacco use presented with one month of persistent vomiting, 20-pound weight loss, headaches, and vertigo. She was found to have hypokalemia (K 2.8 mmol/L) in outpatient labs. Initial computed tomography head at an outside hospital showed vasogenic edema in the left cerebellar hemisphere with mild fourth ventricular deviation, prompting transfer for neurosurgical evaluation. On admission, systolic blood pressures ranged from 180-240 mmHg. Neurologic examination was nonfocal.Magnetic resonance imaging brain revealed left right cerebellar edema with multiple microhemorrhages, compression of the fourth ventricular outflow causing obstructive hydrocephalus, and dolichoectasia of the vertebrobasilar system significantly compressing the medulla. Findings were thought to represent atypical PRES (typical imaging findings of PRES include bilateral symmetric edema) versus dolichoectasia-induced obstruction. The patient was treated with nicardipine infusion for blood pressure control, intravenous dexamethasone, and levetiracetam for seizure prophylaxis. Neurosurgery and neurology were consulted; no surgical intervention was indicated. Keppra and steroids were later discontinued. She remained neurologically intact throughout hospitalization. Plans were made for strict blood pressure management and repeat MRI in 6-8 weeks to assess for resolution of findings. Discussion PRES and vertebrobasilar dolichoectasia can present with overlapping symptoms such as headache, nausea, and vomiting, yet differ in underlying mechanisms and treatment approaches. PRES results from autoregulatory failure and vasogenic edema, typically reversible with adequate blood pressure control. In contrast, vertebrobasilar dolichoectasia involves elongation and tortuosity of vessels that can compress the medulla or fourth ventricular outflow, producing obstructive hydrocephalus. Management of the latter remains unclear due to its rarity, though literature favors posterior fossa fenestration procedures such as, magendieplasty, foraminoplasty, or endoscopic outlet restoration over shunt placement for sustained outcomes when obstruction occurs.In our patient, the coexistence of atypical PRES and dolichoectasia complicated interpretation of imaging and clinical decision-making, underscoring the importance of considering dual pathologies when radiographic and clinical findings do not fit a single diagnostic pattern. This abstract is funded by: none
Polavarapu et al. (Fri,) studied this question.