Atypical Cause of Headache: A Potential Diagnostic Pitfall in Acute Medicine.

Acute headache is a common clinical presentation with a broad differential diagnosis, ranging from benign to life-threatening conditions. Early recognition of atypical causes is essential, particularly when initial investigations are inconclusive. The etiology of acute headache can be broadly classified into primary and secondary causes. Primary headaches occur in the absence of identifiable structural pathology, whereas secondary headaches arise from an underlying organic cause. In this case presentation, a 65-year-old woman presented with a severe headache, which was triggered by an episode of sneezing. The pain was severe, rated 10 out of 10 in intensity, described as a constant dull ache that was felt all over the head but was more prominent in the occipital region, and it was accompanied by photophobia. The pain was not relieved by pain medications and was not associated with fever or trauma. No past history of migraine. On examination, she had no neck stiffness or abnormal neurology. Eye examination revealed bilateral redness and dilated and fixed pupils. Pain continued to be severe despite regular analgesia. A CT head revealed no space-occupying lesion or bleed. She was admitted for close observation and consideration of further investigations, including MRI, lumbar puncture, and inpatient neurology review. Unfortunately, before the MRI, the headache worsened, and the patient also complained of reduced vision in both eyes. An urgent ophthalmology review was requested, which revealed increased intraocular pressure (IOP) in both eyes (right eye 39 mmHg, left eye 40 mmHg, normal IOP: 10-21 mmHg). She was diagnosed with bilateral acute angle-closure glaucoma (AACG). She was given medical management as per the glaucoma protocol; however, as the headache worsened, medical management failed to reduce ocular pressure. She was taken for emergency anterior chamber (AC) paracentesis due to refractory IOP and peripheral iridotomy on the same day as definitive management. Over the next few days, her vision and headache started to improve. She was discharged with regular follow-up with the glaucoma clinic.