Here’s the Case
A 31 year old female patient at term P2G1, had noticed tunnel vision whilst watching her children in the garden. Soon after this she developed a bi-temporal headache. No other symptoms were present.
The only past medical history was of a hearing impairment and hypertension early in the pregnancy.
The clinical examination revealed a bi-temporal hemianopia. This visual field defect(as shown below), must be caused by a lesion at the optic chiasm.
The patient was transferred to a tertiary hospital for an MRI, seen here (of a similar case). There was a significantly increase in the volume of the pituitary.
What are the causes of bitemporal hemianopia in pregnancy?
Physiological- The pituitary volume can increase by up to 30% in late pregnancy resulting in a convexity of the superior surface- up to 12mm in height. This can cause pressure on the optic chiasm resulting in bi-temporal hemianopia. Normal vision returns gradually post delivery, following the gland returning to the original dimensions.
Pituitary Adenoma- Rare in pregnancy accounting for about 1% of adenomas. It is described in bromocriptine treatment for prolactinoma.
Vasculitis- One documented case in pregnancy presenting as bitemporal hemianopia.
Meningioma- One documented case presenting as bitemporal hemianopia
Hysterical- We consider
So if you see it, think MRI, to rule out the nasties.
Case sent in by Dr Peter Ivermee