Intracranial hypotension causing pituitary enlargement.

Chan DWC, et al. BMJ Case Rep 2017. doi:10.1136/bcr-2017-220057 Description A woman aged 67 years was referred with pituitary enlargement identified on CT scan. Imaging was performed to investigate a progressive, incapacitating, 12-month history of nausea, vertigo, gait disturbance and recurrent falls. Her presentation included chronic occipitofrontal headaches, which had increased in severity and were exacerbated by upright posture. She had a history of lumboperitoneal (LP) shunting for idiopathic intracranial hypertension, systemic hypertension, ischaemic heart disease and pulmonary disease secondary to cigarette smoking. Physical examination demonstrated normal cranial nerves, bilateral upper motor neuron signs in both upper and lower limbs and severe gait instability. Her anterior pituitary function testing showed mildly elevated prolactin levels (69.4 μg/L, range 5.2–26.7 μg/L). Adrenocorticotropic hormone (ACTH) deficiency could not be completely excluded on basal testing (ACTH 1.6 pmol/L, range 0.0–10.0 pmol/L; cortisol 245 nmol/L). Other pituitary axes were unremarkable. Formal perimetry confirmed normal visual fields. On MRI examination, the pituitary gland was homogenously enlarged (13x9x12 mm) with a convex superior margin abutting the optic chiasm. There was diffuse pachymeningeal enhancement, tonsillar herniation and a syrinx at C2 level. A diagnosis of intracranial hypotension (IH) was made based on clinical presentation and radiological appearance (figure 1). The LP shunt was revised and her signs and symptoms gradually resolved. MRI examination performed 6 months postoperatively confirmed normalisation of her pituitary anatomy (6x9x10 mm) and resolution of the abnormal features. Basal hormonal levels were retested (ACTH 2.2 pmol/L; cortisol 420 nmol/L) and her hyperprolactinaemia had resolved (21.9 μg/L). This patient had acquired IH due to overdrainage of her LP shunt. IH can be misdiagnosed as pituitary hyperplasia or adenoma.