Severe functional constipation masquerading as acute intracranial infection in an adolescent: a diagnostic pitfall and the risks of empirical mannitol therapy — a case report

Abstract

Abstract Background The differential diagnosis and treatment of non-specific neurological manifestations in adolescents (such as headaches and impaired consciousness) remain a significant challenge in clinical practice. Current clinical routine tends to prioritize the investigation of infectious etiologies, yet functional gastrointestinal disorders are frequently overlooked during screening. Furthermore, in cases of suspected increased intracranial pressure, empirical treatment is often initiated without objective measurement of intracranial pressure, which carries underappreciated risks. Case presentation We report a case of a 14-year-old female patient presenting with sudden bilateral temporal headache, dizziness, and a 21-hour episode of stupor that had spontaneously resolved before hospital arrival. On admission she was alert but lethargic, with normal vital signs, normal neurological examination, and an unremarkable head CT. She was empirically treated with acyclovir and intravenous mannitol for suspected intracranial infection with presumed elevated intracranial pressure. However, subsequent investigations did not support either diagnosis: cerebrospinal fluid analysis was normal with an opening pressure of 70 mmH 2 O (below the pediatric reference range, measured after mannitol administration), fundoscopic examination revealed no papilledema, and brain MRI showed no infectious or structural abnormalities. Persistent headache and lethargy continued despite mannitol therapy. During hospitalization, the patient developed severe constipation. An upright abdominal radiograph demonstrated extensive fecal retention and gaseous distension throughout the colon, together with an incidental finding of non-fusion of the posterior vertebral arches at S1–S2. Following bowel evacuation and discontinuation of mannitol, the persistent headache and lethargy substantially improved, with no recurrence during 3-month follow-up. Conclusions This case illustrates that empirical osmotherapy for presumed intracranial hypertension, in the absence of objective evidence from relevant examinations—such as cerebrospinal fluid pressure measurements—may be both ineffective and potentially harmful. Clinicians should base decisions about osmotherapy on objective intracranial pressure assessment rather than presumptive diagnosis, and should include gastrointestinal evaluation in the work-up of adolescents with persistent unexplained neurological symptoms. Incidental anatomical findings such as isolated posterior arch defects should not be over-interpreted in the absence of dedicated MRI evaluation.

The authors' abstract, as published at the source. BMC Pediatrics, 2026 · DOI ↗