A 28-year-old male presented with the chief complaint of acute onset of right eyelid droop and double vision. There were no symptoms of giddiness, neck stiffness, photophobia, facial droop, slurred speech, swallowing difficulties, limb weakness, numbness, or difficulty with gait. On further questioning, the patient admitted to having pain over the right side of his head for the past 1 day. The patient described a severe, tight headache (8–9/10 on the visual analogue scale) accompanied by nausea, vomiting, and phonophobia. He has experienced similar headaches for 10 years, occurring once or twice a month, often preceded by fatigue and nausea. The pain is typically bilateral over the forehead, moderate in intensity (5/10), and lasts for a day, disrupting daily activities. Paracetamol provides partial relief. No triggers were identified. Seven years ago, he was hospitalized for similar symptoms, including an acute onset of double vision. All neurological and systemic examinations, as well as the investigations, were normal at that time. The diplopia resolved spontaneously after 2 weeks, after which he was discharged from follow-up. 
The patient exhibited right partial third nerve palsy, characterized by partial ptosis, downward and outward deviation of the eye, and impaired extraocular movements, including an inability to adduct the eye and limitations in superior and inferior movements. This was accompanied by binocular diplopia in all positions. The right pupil was 4 mm, slightly oval, with brisk light and accommodation reflexes, while the left pupil was 4 mm round, with normal reflexes and full extraocular movements. The examination of other cranial nerves, limb tone, power, reflexes, sensation, cerebellar function, and gait was normal. Funduscopic examination and neck flexibility were also normal. Blood tests were normal, including fasting glucose, serum VDRL, ESR, CRP, and an autoimmune screen. A normal Tensillon test and repetitive nerve stimulation. Brain MRI with angiography was normal. A lumbar puncture showed an opening pressure of 8 cm H2O, a white cell count of 7 × 10^6/l, glucose of 3.6 mmol/l, and protein of 0.3 g/l.