Diagnostic Testing in Neurosurgery

CT/CT Scan (Computed Tomography):

• radiological test that creates an image after a computer reads x-rays and is used for many parts of the body
• used acutely in emergency rooms for neurosurgical problems such as stroke, trauma, etc.
• easily sees bone (fractures), blood and the brain
• sometimes a contrast given highlights various normal and abnormal structures such as tumors

CT A (CT Angiography):

• allows visualization of the head and neck vessels in 3D
• can assess for narrowing (stenosis) of vessels and aneurysms

Plain X-Rays:

• can be used to view many different parts of the body such as the skull and spine
• often looking for fractures, congenital abnormalities or erosion of pedicles secondary to tumors

Lumbar Puncture (Spinal Tap):

• invasive diagnostic/therapeutic test used to take a sample of the cerebrospinal fluid (CSF) which bathes the brain and spinal cord
• can detect blood (old or new), infections and can be used to inject dye for other tests such as myelogram or radioactive isotopes for a test called a cisternogram.

EEG:

• diagnostic test that uses electrodes attached to the patient’s scalp to pick up electrical signals. These signals are printed on paper in a sequential format that allows the brain waves to be seen and allows the physician to evaluate for seizures.

Cerebral Angiography:

• arteries and veins of the head and neck are seen with this test and a contrast dye has to be given through a catheter so the vessels can be seen
• this is an invasive test using local anesthetic usually around the artery in your leg where a needle is punctured into the vessel and a pliable catheter is inserted into the vessel and directed to the location of interest.
• as the dye is injected a very rapid series of x-rays are taken

Carotid Duplex (Carotid Ultrasound):

• non-invasive, safe and painless test used to detect plaque, blood clots or other flow issues in the carotid arteries
• a transducer is held against a water soluble gel which is on the skin next to the carotid artery. The transducer directs high-frequency sound waves so the pictures of the carotid arteries and pulse wave forms are seen.

Doppler Ultrasound:

• similar to a carotid ultrasound but looks at blood flow in the veins
• used especially for evaluating lower extremity veins

MRI:

• a diagnostic test which is not an x-ray and produces 3D images of body anatomy using magnetic fields and computers
• excellent for looking at different kinds of brain tissue, evaluating the brainstem and the posterior aspect of the brain (the cerebellum) because it removes the boney artifact that a CT scan includes
• excellent for picking up on early strokes
• can be ordered to look at the brain, spine, shoulder, knee, hip, etc.
• depending upon the machine, the patient can be claustrophobic
• magnetic strength measured in Tesla units (i.e. 1.5, 3.0)
• non-invasive except for an IV gadolinium that is given similar to the IV contrast dye of CT scan

MRA:

• non-invasive study used to look at arteries of head and neck using MR technology
• no IV contrast is given
• alternative if patient has “kidney” issues such as in creatonine or BUN
• ability to see aneurysms and AVMs

MRV:

• same as an MRA but looks at the veins and can detect superior sagital sinus thrombosis

fMRI (Functional MRI):

• special MRI of the head that looks at the activity of specific brain regions when stimulating the patient (i.e. language centers- English vs. Spanish sensory strip)
• normally used/recommended when planning for surgery or Gamma Knife

Myelogram/CT of the Cervical, Thoracic and/or Lumbar Spine:

• long-standing, invasive “gold standard” test used to look at spinal disorders
• excellent for looking at cortical bone which is different from an MRI which only sees bone marrow

Brain Biopsy:

• surgical procedure done by a neurosurgeon in a sterile operating room
• this can be done through a small skull opening called a burr hole or through a large skull opening called a craniotomy
• brain tissue (with or without meninges) can be removed and sent to a pathologist
• this type of biopsy is usually used to identify a tumor or infection
• image guidance systems such as “Stealth Navigation” by Medtronics has increased accuracy in biopsies

Nerve Biopsy/Muscle Biopsy:

• surgical procedure done in an operating room
• when all other attempts at diagnosis have failed this procedure is performed

PET (Positron Emission Tomography):

• used to give information about cerebral blood flow, cerebral blood volume and cerebral oxygen consumption and metabolism
• commonly used in a work up for patients with metastatic cancer

EMG/NCS:

• invasive test performed by a neurologist to determine nerve problems with or without muscle issues (i.e. carpal tunnel syndrome or ulnar nerve )