When infection mimics autonomic failure:Postural hypotension secondary to skull base osteomyelitis  

Background
Skull base osteomyelitis (SBO) is an uncommon but life-threatening complication of necrotising otitis externa, typically affecting older adults with diabetes. Presentation is often non-specific, and diagnosis is frequently delayed.

Case

An 84-year-old man with type 1 diabetes, vascular comorbidity and advanced frailty presented with a fall preceded by dizziness on standing. He reported a 6-month history of recurrent falls and severe postural light-headedness. For 3 months, he had persistent right-sided otalgia and offensive otorrhoea treated in primary care with repeated courses of oral antibiotics and steroid-containing ear drops, without referral to an otorhinolaryngology specialist. On admission, he had marked postural hypotension despite cessation of culprit drugs and initiation of fludrocortisone. Initial CT brain imaging was normal, and the sepsis screen was inconclusive.

Ten days after admission, he developed a new right-sided facial palsy. Repeat CT head was again unremarkable. Shortly afterwards, he had profuse bleeding from the right ear. Otoscopy, performed for the first time in a hospital by an otorhinolaryngology specialist, showed florid otitis externa with a polypoid lesion in the external auditory canal. MRI with skull base sequences revealed extensive necrotising otitis externa with right skull base osteomyelitis extending towards the carotid canal. Ear swab culture grew Pseudomonas aeruginosa sensitive to gentamicin and intermediately sensitive to ceftazidime.

High-dose intravenous ceftazidime (2 g three times daily) was commenced under infectious diseases guidance and continued for approximately 7 weeks. Inflammatory markers normalised, and repeat swab cultures were negative. However, follow-up MRI demonstrated partial resolution of the primary osteomyelitis focus with extension into the temporomandibular fossa. Severe postural hypotension persisted despite withdrawal of culprit medication, non-pharmacological measures and fludrocortisone. The patient became increasingly deconditioned and bed-bound, developed prolonged delirium and acute kidney injury stage 3, and died in hospital.

Conclusion
This case illustrates an unusual presentation of pseudomonal skull base osteomyelitis with refractory postural hypotension and recurrent falls, due to involvement of the carotid sinus region. It highlights the need for early assessment by an otorhinolaryngology specialist and skull base imaging in older, frail patients with diabetes who present with chronic ear disease, cranial neuropathy and otherwise unexplained autonomic dysfunction.