Can a brain tumor cause hypotension?

Can a Brain Tumor Cause Hypotension?

Brain tumors typically do not cause hypotension, but in specific circumstances such as hypothalamic injury following sellar region tumor surgery, they can lead to severe vasodilatory hypotension.

Mechanisms of Brain Tumor-Related Hypotension

• Hypothalamic injury during surgery for sellar region tumors can cause refractory hypotension due to decreased vascular tone (low systemic vascular resistance) and relative hypovolemia 1
• This hypotension is typically vasodilatory in nature and resistant to fluid resuscitation alone 1
• Tumors affecting the brainstem or cervical spinal cord can also potentially cause orthostatic hypotension through disruption of autonomic pathways 2

Clinical Presentation

• Most brain tumors typically present with symptoms of increased intracranial pressure including headache, nausea, vomiting, cognitive impairment, personality changes, and gait disturbances 3
• The typical brain tumor-related headaches are holocephalic or unilateral, throbbing, worse in the morning after lying supine, and improve during the day in upright position 3
• Focal neurological deficits may include hemiparesis, aphasia, and visual field deficits 3
• Hypotension is not a typical presenting symptom of brain tumors but may occur post-operatively in specific cases 1

Post-Surgical Hypotension

• After sellar region tumor surgery, some patients may develop severe hypotension due to hypothalamic damage 1
• This hypotension is characterized by:
  • Decreased vascular tone (low systemic vascular resistance index)
  • Relative hypovolemia (low central venous pressure and pulmonary artery wedge pressure)
  • Resistance to fluid resuscitation alone 1
• Treatment typically requires vasopressors, particularly phenylephrine 1
• In cases with associated thyroid insufficiency (which occurs in approximately 27% of these patients), dopamine administration and increased thyroid hormone replacement may be necessary 1

Orthostatic Hypotension with Spinal Cord Tumors

• High cervical or brainstem tumors can cause severe orthostatic hypotension through disruption of autonomic pathways 2
• This can manifest as postural dizziness and syncopal attacks when upright 2
• Management includes preventative measures and potentially alpha-1-adrenoreceptor agonists 2

Important Considerations

• Intracranial hypertension is far more common than hypotension with brain tumors 4
• However, a recent study using non-invasive ICP measurements found that patients with large brain tumors and clinical signs of intracranial hypertension did not necessarily have elevated ICP 4
• In patients with phaeochromocytomas (which can be associated with certain genetic syndromes that also predispose to brain tumors), there is a risk of profound hypotension after tumor excision due to peripheral hypovolemia 3

Clinical Implications

• When encountering hypotension in a patient with a known brain tumor, consider:
  • Recent surgical intervention, particularly in the sellar region 1
  • Potential hypothalamic involvement 1
  • Possible brainstem or high cervical spinal cord involvement 2
  • Endocrine dysfunction, particularly adrenal or thyroid insufficiency 1
• Management should focus on:
  • Vasopressor support (particularly phenylephrine) for vasodilatory hypotension 1
  • Careful fluid management 1
  • Evaluation and treatment of any associated endocrine abnormalities 1