20th July 2023

A 72-year-old woman is brought to hospital by ambulance with a new onset of confusion and fever

A 72-year-old woman is brought to hospital by ambulance with a new onset of confusion and fever. Her wife tells you the symptoms started earlier this morning. There had been no evidence of headache, cough, nausea, vomiting, diarrhoea, urinary symptoms, or rashes leading up to this. The patient has been experiencing worsening back pain and was recently started on a new analgesic by the out of hours doctor.

She has a history of osteoporosis, chronic lower back pain, depression, and anxiety.

Regular medication: mirtazapine 15mg once daily, paracetamol 1g 6 hourly, colecalciferol 400 units daily. Acute medication: tramadol 100mg 6 hourly.

On examination, she is hypertensive, tachycardic, and her temperature is 39.1°C.

She is visibly diaphoretic; however there are no other obvious changes to her skin or appearance.

Other positive examination findings are increased tone in all four limbs with brisk reflexes and confusion.

Blood results, including a full blood count, renal profile, thyroid profile, and CRP are all in normal range.

What is the most likely diagnosis?

Select the SINGLE most appropriate option from the list below. Select ONE option only.