A 48-year-old lady presented to neurology with a 2 year history of progressive leg weakness, rendering her wheelchair-bound. Neurological examination revealed a proximal myopathy. She had a 2 year history of diabetes, and an endocrine opinion was sought to see if the clinical features could be related to diabetes. It was then noted that she appeared Cushingoid, with a blood pressure of 158/92, central obesity, striae and facial acne. She had been amenorrhoeic for 2 years. Endocrine investigations showed: midnight cortisol 345 nmol/l, LH 3.4 IU/l, FSH 17.2 IU/l, oestradiol <70 pmol/l, prolactin 204 mU/l, IGF1 34.3 nmol/l, TSH 1.90 mU/l T4 18.3 pmol/l. She had 2 low-dose dexamethasone suppression tests, which showed failure to suppress cortisol:
|Cortisol (nmol/l)||ACTH (ng/l)||Cortisol (nmol/l)||ACTH (ng/l)|
MRI scan of the pituitary showed a bulky gland, asymmetry of the fossa and stalk deviation. She went on to have inferior petrosal sinus sampling, with a baseline and stimulated ACTH to peripheral ratio consistent with a pituitary source of ACTH.
A diagnosis of a proximal myopathy secondary to ACTH-dependent Cushings disease was considered, however the severity of weakness led to further investigation. Nerve conduction studies were performed, which supported a diagnosis of possible motor neurone disease (MND).
She underwent successful transsphenoidal surgery with a day 4 cortisol of 67 nmol/l, and histology confirming a corticotroph adenoma. She was discharged into a rehabilitation programme on hydrocortisone, and 6 months later her weakness was still present, although her weight and acne had improved.
This unusual case of cushings disease presenting concurrently with MND has not previously been described in the literature. It highlights the importance of looking for other pathologies, and not making the assumption that all the clinical features are due to the cushings disease.