A 32 year old woman presents with worsening lower back pain, difficulty in walking and weakness of both lower limbs for 6 months.

The pain was severe, exacerbated by activity and poorly responsive to analgesics. The lower limb weakness was pronounced when climbing stairs and getting up from chairs.

She also complains of a dry mouth, constipation and urinary frequency.

Serum electrolyte levels are normal, while her ESR is 10 mm/1h.