These are common tests used to help diagnose a neurological condition:

• Brain scans are imaging techniques used to diagnose tumors, blood vessel malformations, or hemorrhage in the brain. These scans are used to study organ function or injury or disease to tissue or muscle. Types of brain scans include computed tomography, magnetic resonance imaging, and positron emission tomography.
• Computed tomography (CT scan) is a noninvasive, painless process used to produce rapid, clear two-dimensional images of organs, bones, and tissues. Neurological CT scans are used to view the brain and spine. They can detect bone and vascular irregularities, certain brain tumors and cysts, herniated discs, epilepsy, encephalitis, spinal stenosis, a blood clot or intracranial bleeding in patients with stroke, brain damage from head injury, and other disorders. The CT scan can be normal in early Huntington’s but atrophy (reduction in overall brain size) can be seen in later disease, particularly involving regions of the basal ganglia deep in the brain.
• Magnetic resonance imaging (MRI) uses computer-generated radio waves and a powerful magnetic field to produce detailed images of body structures including tissues, organs, bones, and nerves. Neurological uses include the diagnosis of brain and spinal cord tumors, eye disease, inflammation, infection, and vascular irregularities that may lead to stroke. MRI can also detect and monitor degenerative disorders such as multiple sclerosis and can document brain injury from trauma. A Functional MRI (fMRI) uses the blood’s magnetic properties to produce real-time images of blood flow to particular areas of the brain. As with CT scans, MRI findings generally become more evident with disease progression, showing atrophy over time in select areas.
• Positron emission tomography (PET) scans provide two- and three-dimensional pictures of brain activity by measuring radioactive isotopes that are injected into the bloodstream. PET scans of the brain are used to detect or highlight tumors and diseased tissue, measure cellular and/or tissue metabolism, show blood flow, evaluate patients who have seizure disorders that do not respond to medical therapy and patients with certain memory disorders, and determine brain changes following injury or drug abuse, among other uses. PET may be ordered as a follow-up to a CT or MRI scan to give the physician a greater understanding of specific areas of the brain that may be involved with certain problems. Scans are conducted in a hospital or at a testing facility, on an outpatient basis. PET scans are typically abnormal in Huntington’s but are currently performed only as part of research protocols, many of which are done at the Feinstein Institute at North Shore.
• Electroencephalography (EEG) monitors brain activity through the skull. EEG is used to help diagnose certain seizure disorders, brain tumors, brain damage from head injuries, inflammation of the brain and/or spinal cord, alcoholism, certain psychiatric disorders, and metabolic and degenerative disorders that affect the brain. EEGs are also used to evaluate sleep disorders, monitor brain activity when a patient has been fully anesthetized or loses consciousness. EEG’s are not always necessary in Huntington’s unless there is concern about seizures based on the individual history.
• Electromyography (EMG) is used to diagnose nerve and muscle dysfunction and spinal cord disease. It records the electrical activity from the brain and/or spinal cord to a peripheral nerve root (found in the arms and legs) that controls muscles during contraction and at rest. EMGs are generally normal in Huntington’s and are not routinely performed.
• Electronystagmography (ENG) describes a group of tests used to diagnose involuntary eye movement, dizziness and balance disorders and to evaluate some brain functions. The test is performed at an imaging center. Small electrodes are taped around the eyes to record eye movements. If infrared photography is used in place of electrodes, the patient wears special goggles that help record the information. Both versions of the test are painless and risk-free. ENG is not often done in Huntington’s unless there are specific causes to pursue it.
• A polysomnogram measures brain and body activity during sleep. It is performed over one or more nights at a sleep center. Electrodes are pasted or taped to the patient's scalp, eyelids and/or chin. Throughout the night and during the various wake/sleep cycles, the electrodes record brain waves, eye movement, breathing, leg and skeletal muscle activity, blood pressure and heart rate. The patient may be videotaped to note any movement during sleep. Results are then used to identify any characteristic patterns of sleep disorders, including restless legs syndrome, periodic limb movement disorder, insomnia and breathing disorders such as obstructive sleep apnea. Polysomnograms are noninvasive, painless and risk-free. As sleep-related disorders are more common in Parkinson’s, the polysomnogram can be helpful in select cases.