Cranial Radiosurgery

10.1055/b-0040-176496

7 Cranial Radiosurgery

Ryan F. Amidon, Christ Ordookhanian, and Paul E. Kaloostian

7.1 Symptoms and Signs (Broad)

Incidental with symptoms (depending on size and location)
Headaches progressively increasing in frequency and severity
Nausea and/or vomiting
Blurred vision, double vision, or loss of peripheral vision
Difficulty maintaining balance
Reduction in sensation or motor control of certain extremities
Difficulty producing speech
Changes in behavior/reduction in awareness
Seizures
Reduction in hearing capabilities

7.2 Surgical Pathology

Intracranial benign/malignant tumor
Vascular malformation

7.3 Diagnostic Modalities

Physical examination
Neurological examination
Cerebral angiography
Diffusion tensor imaging (DTI)
Single-photon emission computed tomography (SPECT) of brain
MRI of brain
PET scan of brain
Optical in vivo imaging (involving bioluminescence and fluorescence)
Biopsy of tissue

7.4 Differential Diagnosis

Vascular malformation
- Arteriovenous malformation (AVM)
Metastatic tumor
- Breast, colon, lung, melanoma, renal cell
Primary tumor (may become metastatic)
- Glioma
  - Astrocytoma (astrocytomas, anaplastic astrocytomas, glioblastomas)
  - Oligodendroglial
  - Mixed glioma (both astrocytic and oligodenrocytic)
- Meningioma
  - Grade I (slow growth, distinct borders)
  - Grade II (atypical)
  - Grade III (malignant/cancerous)
- Schwannoma (i.e., vestibular)
- Craniopharyngioma
- Pituitary
- Primary lymphoma
- Choroid plexus papilloma/carcinoma
- Dermoid tumor
- Hemangioblastoma
- Posterior fossa tumor
  - Medulloblastoma
  - Pineoblastoma
  - Ependymoma
  - Primitive neuroectodermal tumor (PNET)

7.5 Treatment Options

Acute pain control with medications and pain management
If arteriovenous malformation (AVM):
- Embolization to reduce AVM nidus, followed by radiosurgery
If tumor is metastatic:
- Tumor resection surgery (if located in a single area of the brain) followed by radiation therapy
- Radiation therapy (i.e., whole-brain radiation therapy, WBRT)
- Immunotherapy (i.e., Yervoy, Opdivo, Keytruda)
- Intracranial chemotherapy or catheter-mediated chemotherapy (for leptomeningeal metastases); radiation therapy may also be used
- Targeted therapy
  - Tagrisso for non-small cell lung cancer (NSCLC) with genetic alteration to EGFR gene
  - Alecensa for NSCLC with genetic alteration to ALK gene
  - Tykerb for HER2-positive breast cancer
  - Tafinlar and/or Mekinist and Zelboraf for melanoma
If tumor is deemed low grade and can be fully removed in one step (tumor is focused in one area):
- Tumor resection surgery
  - Radiation therapy may be required if tumor cannot be fully removed
If tumor is deemed high grade and cannot be fully removed by surgery:
- Tumor resection surgery if deemed suitable candidate for surgery; may be followed by radiation treatment and chemotherapy (may be supplemented by target therapy) after resection if considered necessary by the radiation oncologist
  - Oncologist will need to determine overall prognosis, Karnofsky performance score, and extent of visceral disease
  - If poor surgical candidate with poor life expectancy, medical management recommended
- Radiation therapy:
  - Conventional radiation therapy
  - Three-dimensional conformal radiation therapy (3D-CRT)
  - Intensity modulated radiation therapy (IMRT)
  - Proton therapy
  - Radiosurgery/CyberKnife treatment (primary treatment for metastases) (see ▶Fig. 7.1):
    
    Fig. 7.1 Graphs demonstrating relationships of extracranial tumor diameter, radiosurgery dose, and postradiation neuropathy. Introduction. In: Carlson M, Link M, Driscoll C, et al, eds. Comprehensive Management of Vestibular Schwannoma. 1st ed. Thieme; 2019
    - The CyberKnife system includes 6-MV compact linear accelerator, two diagonal X-ray cameras, a robotic manipulator, an image detector, a treatment couch, and a treatment planning computer
    - A fractionated approach (small daily doses given over several weeks) may be used