Pituitary Apoplexy

Introduction

Pituitary apoplexy (apoplexy: a sudden neurologic impairment) is a neurosurgical and endocrine emergency that constitutes a clinical syndrome caused by the rapid expansion of a pituitary adenoma secondary to ischemia and /or intratumoral hemorrhage which causes compression of the cavernous sinus, chasm,  optic nerves and hormonal imbalance. The diagnosis is often delayed as approximately ~80% of these patients will have no previous history of a pituitary problem. Pituitary apoplexy may also occur in non-adenomatous or even the normal pituitary gland especially during pregnancy. 

Most cases of pituitary apoplexy present in the fifth or sixth decade with a slight male preponderance and the most common presenting symptoms is sudden severe headache, which is frequently retro-orbital in location.

Pathophysiology

Because of the rich and the complex vascular system pituitary adenomas have a greater propensity to bleed in contrast to other brain tumours. The pituitary gland is located in a bony cavity called the sella turcica covered by the diaphragma sellae superiorly. It lies in close proximity with hypothalamus, optic chiasma and the cavernous sinus. 

Possible reasons for a hemmorhage could be:

• Rapid tumor growth that outstrips the arterial supply
• Constriction of the thin vascular network and finally ischemia, necrosis and haemorrhage
• Aggressive and invasive tumoral behaviour and hemorrhage 

Clinical Presentation

• Headache (present in 95% of the cases)
• Nausea and Vomiting
• Diplopia
• Changes in visual fields
• Ptosis

                            

Risk Factors

• Hypertension
• Head Trauma
• Major Surgery (CABG)
• Coagulopathy
• Dynamic testing of pituitary gland

How is pituitary apoplexy different from Sheehan Syndrome?

Sheehan syndrome refers to pituitary apoplexy of a nontumorous gland, presumably due to postpartum arterial spasm of arterioles supplying the anterior pituitary and its stalk. Normally, the pituitary gland hypertrophies in pregnancy and this hypertrophy, combined with locally released factors, mediates vascular spasm and renders the pituitary more susceptible to infarction from compromised blood flow. It typically presents years later or as inability to lactate after delivery due to prolactin deficiency and amenorrhea due to gonadotrophin deficiency. Also, after delivery, pubic hair fail to grow, and waxy skin depigmentation develops. Signs of hypothyroidism and hypoadrenalism may develop.

Differential Diagnosis 

• Subarachnoid haemorrhage
• Meningitis
• Hypertensive encephalopathy
• Brain abscess 
• Cavernous sinus thrombosis
• Intracerebral hematomas
• Ophthalmoplegic migraine

Diagnosis and Management

MRI is the investigation of choice in a patient with suspected pituitary apoplexy. However, if a MRI scan is not possible, a dedicated pituitary CT is another alternative. 

Medical treatment consists of the following:

• IV Fluids and administer high-dose corticosteroids. Corticotropic deficiency is present in most patients with pituitary apoplexy and it may be life-threatening. Hydrocortisone can be administered as 100–200 mg intravenous bolus followed either by continuous intravenous infusion of 2-4 mg/hour. 
• Immediately evaluate electrolytes, glucose, and pituitary hormones (random serum cortisol, TSH, free T4, prolactin, IGF-1, LH, FSH)
• Administer appropriate endocrinologic replacement therapy alone or combined with transsphenoidal surgical decompression.
  
  
  
  
  Clinically, the most important endocrine dysfunction is adrenocorticotroph hormone (ACTH) deficiency. Resolution of hypersecretory states have been reported following apoplexy, also described as ‘auto-hypophysectomy’. 
  

  
  

Management is controversial in terms of surgical intervention as some experts advocate early surgical decompression in all patients, whereas others adopt a more conservative approach for selected patients (without visual acuity or field defects and with normal consciousness). Outcome is similar with either conservative management or surgery in more recent studies. Long term with follow-up with hormonal evaluation is required to replace the deficient hormones.

Take Home:

• Pituitary Apoplexy is a life threatening cause of acute onset headache
• Maintain a high index of suspicion in any patient with acute headache and a negative conventional CT scan
• Steroid replacement and maintaining the hemodynamic stability for the cornerstone of management

References:

1. Ranabir, Salam, and Manash P. Baruah. “Pituitary Apoplexy.” Indian Journal of Endocrinology and Metabolism 15.Suppl3 (2011): S188–S196. PMC. Web. 17 Apr. 2016.
2. Rajasekaran, S., Vanderpump, M., Baldeweg, S. et al. (2011) UK guidelines for the management of pituitary apoplexy. Clinical Endocrinology, 74, 9-20. 
3. Solomon, Adriana Elena, et al. "Pituitary apoplexy: clinical features, management and outcome. Clinical study and review of the literature." Romanian Neurosurgery 22.1 (2015): 69-77.