Tumors of the Nervous System

All of the different types of primary (not metastasis) nervous system tumors can be challenging to remember. I really have not interacted with the material since I studied for STEP 2 until this past week while on Neurosurgery. We had several cases for resections of brain tumors and so it seemed appropriate to refresh and revisit tumors of the nervous system. 

Quick Facts From NIH

• 18,000 patients in the USA are diagnosed with a brain tumor every year
• Nervous system tumors are the second most common cause of cancer in pediatrics (Leukemia is first)
• Nervous system tumors are not as common in adults but come in 7th in the order of Lung, Colon, Breast, Pancreas, Prostate, Leukemia and then Brain/Nervous system
• Metastatic tumors are more common than primary, so when you see a brain tumor on a CT, it is more often metastasis from a different site
• Primary Brain tumors more common in men, except for meningiomas
• Brain tumors in adults are 70% located in the supratentorial and 30% infratentorial
• Brain tumors in Peds are 70% infratentorial and 30% supratentorial

Symptoms of Brain Tumors - often persistent and progressive (tumor stays and grows over time)

• Worsening, constant headache, headache wakes them up at night
• Seizures
• Focal neurologic deficits - visual loss, arm or leg weakness, facial drooping
• Personality changes
• Altered mental status

CT scan is the initial test. If a brain tumor is suspected, an MRI and brain biopsy would be the next step. 

Gliomas - the most common primary brain tumor and the term "glioma" is used for these tumors because they have histology representative of glial cells (astrocytes, oligodendrocytes and ependymal cells)

1. Astrocytomas (also referred to as gliomas). The cell of origin is an astrocyte. There are four I-IV and are graded on a scale of severity. Most common brain cell tumor. 

• Grade I - known as pilocytic glioma/astrocytoma. More common in children. Surgical resection is often curative.
• Grade II - known as low-grade astrocytoma. Surgical resection is usually not enough and need additional therapy such as chemo and radiation. 
• Grade III - known as anaplastic glioma/astrocytoma
• Grade IV - known as glioblastoma multiform. More common in adults. Prognosis is dismal. Tumor can be resected but will not be curative. Pt will have chemo (tamezolamide and carnustine) and radiation treatment in addition. Can see "butterflying" when the tumor crosses the corpus callosum

2. Oligodendroglioma - less common and more often seen in adults. Most often found in the frontal lobe. 

• Treatment will be PVC chemo (procarbazine, vincristine and CeeNU/lamustine), radiation and surgical resection
• Tends to recur and become more treatment resistant

3. Ependymoma -Ependymal cells are cells that line the ventricles so the most common location will be inside the ventricles.

• Risk factor is Neurofibromatosis type 1
• A symptom could be cauda equina symptoms or hydrocephalus
• treatment is surgical resection, radiation and chemotherapy

Meningioma - origin is menigial cells of the dura mater. 

• Sometimes, can see a dural tail connecting the tumor to the dura mater. 
• Can extend into the epithelial cells
• Primarily see these in adults and are usually benign

Medullablastoma - origin unknown but will arise in the medulla

• Mostly seen in children
• Tends to block the fourth ventricle since and can cause obstructive hydrocephalus
• Gait issues are a common symptom
• Diplopia from impingement on CN VI
• Treatment is surgical resection, chemo and radiation

Schwannoma - originates from schwann cells which are myelinating cells of the peripheral nervous system.

• Risk NF-1 and NF-2 (bilateral acoustic neuromas) 
• Commonly affects CN VIII and can see sensorineural hearing loss and vestibular symptoms
• Treatment is surgical resection and prognosis is good

Hemangioblastomas

• seen on the cerebellum
• Assoc with von Hipple-Lindau 

Craniopharyngiomas

• more common in children
• arises from the pituitary stalk
• can have endocrine abnormalities and panhypopituitarism, bitemporal hemianopsia from compression of the optic chiasm

 Brain Metastases

• most common cause of brain tumors
• Mets will come from commonly from these locations - lung, skin and breast