CHPT 4: Diagnostic Tests and procedures

electrodiagnostic procedures: diagnostic procedures used to evaluate the function of the nervous system by recording the electrical signals produced in the brain, spinal cord, and peripheral nerves

electroencephalogram (EEG): record of the minute electrical impulses of the brain measured as alpha, beta, delta, and theta waves; used to identify neurologic conditions that affect brain function and level of consciousness

evoked potentials: record of minute electrical potentials (waves) that are extracted from ongoing EEG activity to diagnose auditory, visual, and sensory pathway disorders; also used to monitor the neurologic function of patients during surgery

polysomnography (PSG): recording of various aspects of sleep (e.g., eye and muscle movements, respiration, and EEG patterns) to diagnose sleep disorders

lumbar puncture (LP): introduction of a specialized needle into the spine in the lumbar region for diagnostic or therapeutic purposes, such as to obtain CSF for testing; also called spinal tap

magnetic resonance imaging (MRI): nonionizing imaging technique using magnetic fields and radiofrequency waves to visualize anatomic structures (especially soft tissue), such as the tissues of the brain and spinal cord

magnetic resonance angiography (MRA): magnetic resonance imaging of blood vessels to detect pathologic conditions, such as thrombosis and atherosclerosis

intracranial MRA: magnetic resonance image of the head to visualize the vessels of the cerebral arterial circle (circle of Willis), which is a common site of cerebral aneurysm, stenosis, or occlusion

extracranial MRA: magnetic resonance image of the neck to visualize the carotid artery circulation

nuclear medicine imaging: radionuclide organ imaging

single-photon emission computed tomography (SPECT) brain scan: scan combining nuclear medicine and computed tomography to produce images of the brain after the administration of radioactive isotopes

positron-emission tomography (PET) : technique combining nuclear medicine and computed tomography to produce images of brain anatomy and corresponding physiology; used to study stroke, Alzheimer disease, epilepsy, metabolic brain disorders, chemistry of nerve transmissions in the brain, and so on; provides greater accuracy than SPECT, but is used less often because of cost and the limited availability of the radioisotopes

radiography: x-ray imaging

cerebral angiogram: x-ray of blood vessels in the brain after intracarotid injection of contrast medium

computed tomography (CT) of the head: computed tomographic (x-ray) images of the head used to visualize abnormalities, such as brain tumors and malformations

myelogram: x-ray of the spinal cord obtained after intraspinal injection of contrast medium

reflex testing: test performed to observe the body′s response to a stimulus

deep tendon reflexes (DTR): involuntary muscle contraction after percussion at a tendon (e.g., patella or Achilles) indicating function; positive findings are either no reflex response or an exaggerated response to stimulus; numbers are often used to record responses

Ø = no response (absent reflex)

1+ = diminished response

2+ = normal response

3+ = more brisk than average response

4+ = hyperactive response

Babinski sign: pathologic response to stimulation of the plantar surface of the foot; a positive sign is indicated when the toes dorsiflex (curl upward); also called Babinski reflex

transcranial Doppler sonogram: image made by sending ultrasound beams through the skull to assess blood flow in intracranial vessels; used in the diagnosis and management of stroke and head trauma