Introduction:
The syndrome of inappropriate secretion of anti-diuretic hormone (SIADH) is a condition of euvolaemic hyponatraemia sometimes associated with disorders affecting the central nervous system (CNS). Gradenigo syndrome is a rare but serious complication of otitis media, defined by the triad of otitis media, severe orbito-facial pain and ipsilateral sixth cranial nerve palsy.
Case:
A 67-year-old female presented with worsening left-sided otalgia with discharge, nausea and vomiting, hearing impairment with intermittent tinnitus, and new onset diplopia. She had profuse left ear sloughy discharge, a left sixth cranial nerve palsy and CT imaging demonstrating left mastoid effusion with sclerosis at the petrous apex, which was felt to fulfil criteria for Gradenigo syndrome.
She was also severely hyponatraemic at presentation, with serum sodium 112mmol/L (135-145), serum osmolality 239mmol/kg (285-295), urine sodium 57mmol/L and urine osmolality 512mmol/kg. She was a non-smoker with a history of hypertension and dyslipidaemia. Regular medications were valsartan 80mg daily, amlodipine, atenolol and atorvastatin. She was clinically euvolaemic with normal renal function and cortisol level (470nmol/L). Incidentally, she had mild hyperthyroidism with TSH 0.2mIU/L (0.40-3.50) and free T4 26.3pmol/L (10.0-20.0), and was found to have a multinodular thyroid.
She was admitted to Intensive Care for close monitoring, intravenous broad-spectrum antibiotics and a strict 1.2 litre daily fluid restriction for management of SIADH. Valsartan was withheld. Her sodium improved gradually over 6 days and she underwent an operative left myringotomy and insertion of grommet on day 7. Her symptoms improved and she was discharged by day 13 on a prolonged course of antibiotics. Serum sodium normalised to 135mmol/L by discharge.
Conclusions:
Gradenigo syndrome is a rare entity which can cause complications that affect the CNS. Our case is the first to demonstrate acute SIADH being possibly linked with this syndrome in an adult.