Most primary brain tumors location can be identified by the conditions they cause

Medulla oblongata

• Tumors in this area cause big problems (benign or malignant)
• Relays sensory information to thalamus and other portions of the brain stem
• Autonomic centers for regulation of cardiovascular, respiratory, and digestive system activities

Pons

• Conduction of impulses
• Relays sensory information to cerebellum and thalamus
• Subconscious somatic and visceral motor centers

Cerebellum

• Referred to as “little brain”
• Located under the cerebrum and over the medulla
• Coordination of muscle activities, balance, posture,
• Ataxia- reeling walk
• Primary tumors of the cerebellum cause : inability to coordinate voluntary muscle movements; unsteady movements and staggering gait (occurs mostly in children)

Midbrain

• “Righting reflex” - Any of various reflexes that tend to bring the body into normal position in space and resist forces acting to displace it out of normal position. Also called static reflex.
• Knowing which way is up

Diencephalon

Consists of thalamus and hypothalamus

• Hypothalamus

  • Regulates body temperature, blood pressure, G.I secretions(visceral activities), emotional states-(rage, anxiety)
• Thalamus
  • Sensory integrating organ-relay
  • Senses temp and pain
  • Primitive response

Pituitary

• Located in sela tursica
• Pituitary also know as hypophysis
• Produces hormones
• ACTH-weight control
• TSH – thyroid stimulating hormone (controls metabolism)
• FSH – follicle stimulating hormone (controls ovulation in women and sperm maturation in males)
• ADH – anti dieretic hormone
• Pituitary tumors:
• Histology is chromophobe adenomas (benign)
• Pituitary tumors are almost always benign / patient often develops tunnel vision because of the location of the
• **Radiation therapy is the treatment of choice
• Lateral wedged pair and open vertex field is used to treat pituitary

• Dose taken to 5000cGy
• Most common type
• Chromophobe adenoma

Cerebrum

• Does grow as a child
• Sulcus-folds that grow to accommodate memory (way the brain grows)
• Several sulcus called a gyrys
• Controls Conscious thought processes, intellectual functions, Memory storage and processing
• Also Conscious and subconscious regulation of skeletal muscle contractions

Limbic system

• Fear, hunger, pleasure, sex
• Oldest part of brain besides medulla oblongata

Pineal body

• Biological clock-when to release egg in woman
• Regulates gonads

Supratentorial area- is the cerebrum and diencephalons which contains the thalamus, hypothalamus, pituitary, and pineal body (they are separated by the meninges)

GENERALIZATIONS OF BRAIN TUMORS:

• Mostly seen in adult white males ages 50-80yrs
• Also between 5-10 years-pediatric cases
• most common brain tumor is metastases
• most common brain primary is Glioma (Astrocytoma)
• Most common pediatric brain tumor - meduloblastoma
• 1.5% of all tumors
• 20% of pediatric tumors
• note: most common pediatric cancer is leukemia (dont be fooled by wording!)
• Posterior fossa-nickname for cerebellum region
• Pituitary Tumors are most commonly chromophobe adenomas given a dose of 4500 - 5000 cGy (standard glandular dose)

• Etiology:environmental factors (exposures), previous radiation are causes
• Locally invade, spread by direct invasion
• Low grade-benign / High Grade-malignant
• No blood born mets, no lymph node mets
• Can have CNS involvement
• Spinal tap below L2 to check
• Symptoms are evident By area involved,
• Prognosis- grade is most important
• Treatment for primary brain tumors: Depends on location

• Must be extra careful with medulloblastoma cases!!! See Below

Generalizations for Medulloblastoma:

• Cerebrospinal axis treatment : whole brain with posterior fossa boost plus spine field

• Whole brain to a dose of 3000-3500cGy
• Posterior fossa boost (or involved area) - additional 1000cGy
• CSF(cerebro spinal fluid)-3000cGy
• Lower doses given in children
• Blast cells
• CSF
• CSF flows in subarachnoid space till L2
• SCF sac
• Can inject chemo to treat
• Called Intra-Thecal

 

For treatment of medulloblastoma :

• Must be careful of the Spinal cord when you Overlap fieldsMust be careful with overlap
• Don’t want transverse myelitis to occur if cord is overdosed
• Transverse myelitis should never occur if proper treatment is given