*Read from printed notes – Ian Brown

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Notes from emedicine.com

Background

  • Brain tumors may originate from neural elements within the brain, or they may represent spread of distant cancers.
  • Primary brain tumors arise from CNS tissue
    • account for roughly half of all cases of intracranial neoplasms
    • The remainder of brain neoplasms are caused by metastatic lesions.
  • In adults, two thirds of primary brain tumors arise from
    • structures above the tentorium (supratentorial)
    • In children, two thirds of brain tumors arise from structures below the tentorium (infratentorial).
  • 95% of brain tumours
    • Gliomas
      • Low grade
        • Astrocytoma
          • common in young people
      • High grade
        • Anaplastic astrocytoma
        • Gliobastoma multiforme
    • metastases
    • meningioma
    • pituitary adenoma
    • acoustic neuroma
  • Classification by tumor cell type is irrelevant to the emergency physician because emergent treatment is the same regardless of the tumor type.

Neoplasms, brain. CT images of several tumor type...

Pathophysiology

  • Tumors of the brain produce neurologic manifestations through a number of mechanisms
  • Small, strategically located tumors may damage specific neural pathways traversing the brain
    • Tumors can invade, infiltrate, and supplant normal parenchymal tissue, disrupting normal function.
  • Because the brain dwells in the relatively restricted repository of the cranial vault, growth of intracranial tumors with accompanying edema may compress normal tissue and impair function
    • Space-ocupying lesion
    • May manifest vision problems, and headaches
  • Tumors proximal to the third and fourth ventricles
    • may obstruct the flow of cerebrospinal fluid
      • leading to hydrocephalus
  • In addition, tumors generate new blood vessels (ie, angiogenesis)
    • disrupting the normal blood-brain barrier
    • causing edema
  • The cumulative effects of tumor invasion, edema, and hydrocephalus may elevate the intracranial pressure (ICP)
    • impair cerebral perfusion
  • Intracranial compartmental rise in ICP may provoke shifting or herniation of tissue
    • under the falx cerebri
    • through the tentorium cerebelli OR
    • through the foramen magnum
  • Slow-growing tumors
    • particularly tumors expanding in the so-called silent areas of the brain
      • such as the frontal lobe
    • may be associated with a more insidious course
    • These tumors tend to be larger at detection
  • Most primary brain tumors do not metastasize
    • Of those neural element tumors that do
      • intraparenchymal metastasis generally precedes distant hematogenous dissemination via the arterial system
  • Metastatic brain tumors from non-CNS primary tumors may be the first sign of malignancy
    • or they may herald a relapse.
    • Nonetheless, the signs and symptoms of brain metastases simulate those of primary brain tumours

Diagnosis

History

  • headache
  • altered mental status
    • memory loss and decreased alertness
      • suspect: frontal lobe tumour
    • depersonalization, emotional changes, and behavioral disturbances
      • Temporal lobe neoplasms
    • increased irritability, unsteadiness, ataxia, headache, vomiting, and progressive obtundation
      • paedetric posterior fossa tumour
  • ataxia
  • nausea & vomiting
  • weakness & gait disturbance
  • Sensory disturbance
    • vision
    • smell
    • hearing
      • intermittent (then progressive) hearing loss, disequilibrium, and tinnitus
        • acoustic neuroma
  • focal seizures, fixed visual changes, speech deficits, or focused sensory abnormalities
    • onset of symptoms usually is insidious, but an acute episode may occur with
      • bleeding into the tumor, or
      • when an intraventricular tumor suddenly occludes the third ventricle
    • seizures, hemiparesis, visual field cuts, speech difficulties, and intellectual disturbance.
      • Supratentorial tumors in children
  • Pituitary adenoma
    • Non-functional
      • when large enough can compress optic chiasma
      • causing vision problems
    • Hypersecretory
      • secrete prolactin
      • women
        • amenorrhea-galactorrhea syndrome
      • men
        • impotence

Physical examination

  • Increased Intracranial pressure
    • papillaedema
  • Diplopia
    • compression/displacement of 6th CN
      • at base of brain
  • Impaired upward gaze (Parinaud syndrome)
    • may occur with pineal tumours
  • Homonymous hemianopia
    • tumour of occipital lobe
  • Anosmia
    • frontal lobe tumours
  • Brainstem and cerebellar tumors
    • cranial nerve palsies
    • ataxia
    • incoordination
    • nystagmus
    • pyramidal signs
    • sensory deficits
  • Facial, cochlear, and vestibular CN dysfunction
    • run through the cerebellopontine angle
    • Vestibular nerve
      • acoustic neuroma

Imaging studies

  • CT
    • Intravenous contrast
      • for tumour idenfication
    • May appear
      • hypodense
      • isodense
      • hyperdense
  • MRI
    • helpful in identifying
      • tumours in posterior fossa
        • including acoustic neuroma
      • haemorrhagic lesions
  • Xray
    • tumour on sella turcica
      • pituitary tumour/adenoma
  • Lumbar puncture
    • not needed
Complications

  • Acute hemorrhage into a tumor
    • Brain neoplasms predisposed to hemorrhage include lung cancer, melanoma, and choriocarcinoma.
  • Lesions near the third ventricle can cause
    • paroxysmal symptoms of headache, syncope, or mental status change.
    • vomiting, ataxia, memory changes, visual disturbances, or personality change
      s may occur
  • Episodic increases in ICP
    • secondary to pressure arising from blockage of cerebrospinal fluid outflow
  • Sudden death
    • obstruction of outflow drainage from the third ventricle
  • Sudden increases in ICP
    • may lead to life-threatening brain herniation
    • shifts the brain parenchyma in the direction of least resistance:
      • caudally through the foramen magnum (posterior fossa tumors) or
      • transtentorial apertures.
  • Some pituitary tumors are hormonally active
    • acromegaly
    • galactorrhea

Treatment

Prehospital Care

  • Supportive
  • Airway disturbance
    • breathing difficulty
  • Signs of pronounced elevation in ICP
  • Impairment of consciousness
    • May necessitate definitive airway control with endotracheal intubation
    • Hyperventilation.

Emergency Department Care
  • Corticosteroids
    • may dramatically reduce signs and symptoms related to cerebral edema
    • experience relief within the first few hours of steroid therapy
      • Dexamethasone
        • agent of choice
          • minimal salt-retaining properties
  • For patients with signs or symptoms of impending herniation and airway compromise
    • consider use of adjunctive medications for rapid sequence intubation
    • These might include lidocaine and medication for rapid-onset neuromuscular blockade, with precautions to diminish fasciculations
    • Induction agents, such as thiopental, may be used
    • After definitive control of the airway,
      • consider gentle hyperventilation
  • Mannitol
    • Hyperosmolar agent
    • Reduce ICP & cerebral oedema
      • creating an osmotic gradient across an intact blood-brain barrier
      • between cerebrospinal fluid in arachnoid space and blood plasma
    • May have rebound
      • Increases in ICP
      • makes its use problematic

Surgical intervention/Radiotherapy

    • Tumour resection/debulking
    • Installation of ventricular shunt
    • Placement of radioactive implants

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