Pituitary apoplexy was first described by Bailey in 1898 (2), but was not named until Brougham, Heusner and Adams published an article in 1950 describing five patients who died suddenly and whose autopsy revealed haemorrhage in a pituitary adenoma. The condition should really be called pituitary adenoma apoplexy, as infarction of a normal pituitary gland has other causes, as in Sheehan's syndrome. Hypertension, anticoagulation treatment and major surgical interventions are risk factors. Pituitary apoplexy is a relatively rare condition. Clinical pituitary apoplexy occurs in only 0.6–9 % of pituitary tumours (4). However, radiological examination reveals haemorrhagic areas in 10–20 % of pituitary adenomas. New Belgian and Icelandic prevalence figures for pituitary adenoma indicate about 100 cases per 100 000 people (5, 6).
The most usual presenting symptoms are headache (80–100 %), nausea (80 %), impaired visual acuity (56 %), temporal field of vision impairment (34–70 %), a degree of ophthalmopalsy (45–57 %) and a reduced level of consciousness (13–70 %) (4). Compression of the optic chiasm causes visual disturbances and field of vision impairment, while compression of the cavernous sinus may cause affection of the third, fourth and sixth cranial nerves. The third cranial nerve (oculomotor nerve) is most commonly affected, followed by the sixth (abducens nerve). Pituitary apoplexy is the presenting symptom of pituitary adenoma in 50–80 % of patients.
Pituitary apoplexy can be a dangerous condition that may result in sudden death, probably due to central adrenal insufficiency. However, this is rare in modern times with CT and MRI diagnostics. Infarction or necrosis of the pituitary gland causes hypopituitarism that is permanent in 50–80 % of cases. Field of vision impairment may also be permanent, but improves in most cases if the patient has surgery in time.
Our patient developed hyponatraemia. This occurs in some cases of pituitary apoplexy (10–40 %) and is caused by hypocortisolism (7). A fall in adrenocorticotropic hormone (ACTH) and cortisol leads to increased ADH. The condition therefore presents as normovolaemic hyponatraemia and a biochemical picture resembling that of SIADH. In central adrenal insufficiency, the renin-angiotensin-aldosterone system is preserved, and as a result patients do not develop hyperkalaemia as happens with primary adrenal insufficiency. This is consistent with the laboratory findings for our patient. SIADH can arise in connection with a number of other conditions that may cause acute headache. Examples are acute subarachnoid haemorrhage or other brain haemorrhage, meningitis and encephalitis. A particularly relevant differential diagnosis in the present case is cavernous sinus thrombosis, which may cause SIADH, headache, and the same cranial nerve deficit as our patient experienced.
Traditionally, the majority of patients with pituitary apoplexy have undergone surgery, but in cases of a stable situation without major field of vision impairment or cranial nerve deficits, a conservative approach may be an equally good option. This is increasingly being chosen. The patient must then undergo close clinical monitoring and field of vision tests, to enable intervention in the event of exacerbation. If the tumour is a prolactinoma, there is a high probability of a good response to medical treatment with a dopamine agonist. This favours conservative treatment. The decision of whether to choose a conservative or a surgical approach should be made by a multidisciplinary team. The most important treatment initially is rapid administration of corticosteroids, haemodynamic stabilisation and correction of electrolyte imbalances. In cases of reduced consciousness or increasing loss of vision, the patient should undergo emergency surgery. All patients must be followed up by an endocrinologist with respect to observation and substitution treatment for hormone imbalances (8).
This case study underscores the importance of systematically assessing and observing patients with severe, persistent headache with acute onset. Arriving at the correct diagnosis may be difficult. In our case it took five days. We had accepted the results of CT scans on which changes in the pituitary gland had been overlooked. The incipient diplopia on the third day might have shifted the focus to pathology at the base of the brain. Only when clinically distinct abducens nerve palsy and incipient hyponatraemia occurred on the fourth day, did it lead our thinking in the direction of the diagnosis. Interdisciplinary discussion between neurologist, internal medicine specialist and radiologist was important.
An MRI head scan is an important examination that should have been carried out earlier in the case of an unexplained neurological condition such as this one. When the examination finally was ordered, a further day passed before it was carried out. There is limited MRI capacity at our hospital, and referrals have to be carefully prioritised on the basis of good clinical information. It may also be difficult to have an MRI carried out at the desired time because of an influx of emergency scans. Inpatients only have access to MRI during the day and not in the weekends. Both clinicians and radiologists want increased MRI capacity, but this is difficult given the current financial constraints.
Another lesson from this case history is that renewed scrutiny of previously performed radiological scans in the light of new clinical information may lead to the discovery of pathology that has been overlooked.