Critically ill patient with a brain tumor
With advanced imaging (i.e. computed tomography, magnetic resonance imaging) becoming widely available to veterinary practices, brain tumors are being commonly diagnosed as a cause of clinical neurological signs in dogs and cats. Symptomatic management, surgical excision via craniotomy and external beam radiation therapy are currently the most common treatments for intracranial neoplasia in veterinary medicine.
The main goals of the initial stabilization in a critically ill patient with a brain tumor are to normalize intracranial pressure (ICP) and stop life-threatening seizures. Brain tumor together with tumor-associated cerebral edema can lead to intracranial hypertension, decreased cerebral blood flow and, potentially, brain herniation and death. Hyperosmotic agents (i.e. mannitol, hypertonic saline) with their rheologic and osmotic effects will lower intracranial pressure and increase cerebral perfusion pressure, and cerebral blood flow. Head elevation to 30° facilitates the venous blood drainage and helps decrease ICP. Corticosteroid effect on the peritumoral edema has been well documented and steroids (e.g. dexamethasone) are widely used in the management of brain tumors with surrounding edema.
Seizures are common and potentially devastating complication of brain masses. Cluster seizures and status epilepticus must be aggressively treated with an appropriate anticonvulsant therapy to prevent systemic complications of uncontrolled seizures. Various intravenous drugs (e.g. diazepam, midazolam, phenobarbital, levetiracetam, propofol) can be used alone or in combination in repeated boluses or as a constant rate infusion.
To enable appropriate blood perfusion and nutrition of the brain, normotension, normocapnia, adequate blood oxygenation, euvolemia, normolactatemia and euglycemia must be maintained. In critically ill neurological patient with inappropriate breathing pattern and inadequate ventilation and/or oxygenation, severely compromised mentation or increased risk for aspiration pneumonia controlled positive pressure ventilation may be necessary.
Dogs with palliatively treated primary brain tumors, particularly those with infratentorial tumors (i.e. tumors in the cerebellum, pons, or medulla), have a poor prognosis, while those with supratentorial tumors have reported survival times of more than 3 months.
Compared to palliative therapy alone, substantially better survival times have been reported when brain tumors were treated with radiotherapy and surgery, with little difference between survival after surgery versus radiotherapy.
Furthermore, radiotherapy used in the early phase of the treatment can help with the stabilization of neurological signs.
In conclusion, whenever feasible, surgical treatment or/and radiation therapy should be pursued after successful medical stabilization of a critically ill patient with a brain tumor.
If you have noted any problems with your animal, please consult your veterinarian.
Article by Marko Pipan
Photos: Animal Hospital Postojna and Radioterapia u Psa