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An EEG recording is usually requested to investigate the presence of epilepsy, but is also used to look at brain function according to brain waves in general. A routine EEG should consist of at least 25 electrodes and 19 channels, with a minimum duration of 20 minutes. Overnight or long-term EEG's may also be requested for a more accurate assessment. Electromyography (EMG) and nerve conduction studies are used to investigate the integrity of the peripheral nervous system. It involves electrical stimulation of various peripheral nerves to assess entrapment syndromes, peripheral neuropathies and plexus pathologies. The EMG part consists of using a thin needle inserted into various muscles to examine the electrical activity within the muscle. This procedure can give useful information about the integrity of the entire course of a nerve from nerve root level to the muscle, as well as information on a muscle disease process. This test, also known as auditory brainstem response (ABR), evaluates the peripheral and central part of the auditory nerve by using earphones to deliver click stimuli to the ear and electrodes on the head to pick up the signals generated by the nerve and the brain. It is especially useful in determining hearing levels and integrity of the auditory nerve. Somatosensory evoked potentials (SSEP) are used to evaluate the central nervous system with emphasis on the spinal cord and conduction of impulses through to the surface of the brain. Often used to assess the progression of Multiple Sclerosis and often used intra-operatively to monitor the integrity of these pathways during surgery. Long term monitoring is used in the evaluation of patients with intractable epilepsies or difficult to treat epilepsy syndromes. It involves connecting the patient to an EEG system for a few days, usually 4 to 5 days, to continuously monitor the brainwaves and record the exact origin of an epileptiform dysfunction. This information can then be used to decide whether a patient might benefit from epilepsy surgery. Polysomnography is derived from EEG technology and is used to evaluate sleep and its disorders, most common of which is probably obstructive sleep apnea. A polysomnogram should preferably be performed overnight and should record at least the following: 2 EEG channels, 2 eye movement channels, muscle tone, nasal airflow, chest and abdominal movement, EKG, snoring, body position and leg movements. A multiple sleep latency test (MSLT) is performed during the day, after a full night polysomnogram, to assist in the diagnosis of narcolepsy and evaluate excessive daytime sleepiness. It consists of 4 to 5 sessions of 30 minutes in duration, separated by a compulsory waking period of 90 minutes. Sleep architecture and latency to REM sleep is measured. Continuous positive airway pressure (CPAP) is a therapy used to treat obstructive sleep apnea. After the diagnosis is confirmed with overnight polysomnography, an overnight CPAP-titration is done to determine the optimal pressure needed to eliminate all apneas. Bilevel positive airway pressure is used to treat central sleep apnea and breathing disorders in neuro-muscular disorders as well as in Cheynne-Stokes breathing. An overnight BiPAP-titration is needed to determine the optimal inspiratory and expiratory pressures. Electronystagmography is used to evaluate the systems in the brain and cochlea responsible for balance. It involves a series of tests using eye-movement monitoring and moving lights to evoke responses from the different neuronal pathways. Neurobiofeedback is a form of therapy during which the brain is conditioned to generate more optimal brain waves, very effective for treating insomnia, ADD, ADHD and other minimal brain dysfunctions. Transcranial Doppler studies are used to evaluate the circulation and efficiency of blood flow into the brain and through the brain, thus evaluating the risk of aneurisms and increased intracranial pressure. EMG biofeedback is a new technique used to evaluate as well as train the muscular system, especially in disorders of the sphincter muscles. |
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