NCS and EMGs diagnose nerve and muscle disorders, such as carpal tunnel syndrome, neuropathy, ALS, muscular dystrophies, myopathies and myasthenia gravis. During the NCS portion of the test electrodes and a stimulator are placed on the skin over the nerve that is being tested. A series of brief electrical impulses is given to stimulate the nerve. The EMG exam is performed by inserting a very thin, disposable needle into several muscles, one at a time, to record waveforms and listen to sounds produced by the muscle at rest and during small movements. 

The Penn State Health Clinical Neurophysiology Laboratory has received exemplary status by the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM). The AANEM Electrodiagnostic (EDX) Laboratory Accreditation Program is a voluntary, peer-review process that identifies and acknowledges EDX laboratories that achieve and maintain the highest level of quality, performance and integrity based on professional standards.

Some conditions tested for:

• Carpal tunnel syndrome
• Other nerve compressions and injuries
• Polyneuropathies
• ALS (Lou Gehrig’s disease)
• Muscular dystrophies and other muscle disorders
• Myasthenia gravis and Lambert-Eaton syndrome 
   

Evoked Potentials (EP), also called evoked responses, are recordings of electrical activity from nerves to the eyes, ears or skin in response to electrical stimulation. During EP testing, electrodes are placed over the head to record waveforms in response to visual stimuli (looking at patterns on a screen), auditory stimuli (sounds produced through headphones) or small electrical pulses given to the arm or leg. Each type of EP looks at a different neurological pathway:

• VEP – Visual Evoked Potential
• BAEP – Brainstem Auditory Evoked Potential
• SSEP – Somatosensory Evoked Potential

Some conditions tested for:

• Multiple sclerosis
• Optic neuritis
• Spinal cord injuries

Autonomic testing consists of four separate tests. These tests include:

• Quantitative sweat measurements
• Heart rate deep breathing
• Valsalva maneuver
• Head-up tilt table testing

Some conditions tested for:

• Abnormal heart rate or rhythm/heart palpitations (especially positional)
• Blood pressure changes with positional change (especially standing)
• Heat intolerance, sweating too much or not enough
• Lightheadedness and fainting (especially upon standing)

A routine EEG records the electrical activity of the brain for 20 to 40 minutes from wires placed on the scalp, with simultaneous video recording. It can be done in the outpatient or inpatient setting. Activation procedures, such as hyperventilation, intermittent photic stimulation and overnight sleep deprivation prior to the EEG, increase the chance of recording epileptiform activity and are commonly performed. 

EEGs assist physicians in the diagnosis of seizures, status epilepticus (ongoing continuous seizures or very frequent seizures), certain epileptic syndromes in children (epileptic encephalopathies), brain infections (herpes encephalitis) and some rare forms of degenerative brain disease (Creutzfeldt-Jakob disease). EEGs are also helpful in the evaluation of the level of coma in unconscious patients.

Conditions tested for with routine EEG:

• Any symptom suspected to be seizure 
• Suspected epileptic encephalopathy in children 
• Evaluation of level of coma in unconscious patients 
• Suspected nonconvulsive status epilepticus (NCSE) in confused or comatose patients 
• Suspected herpes encephalitis 
• Suspected Creutzfeldt-Jakob disease 

The ambulatory EEG is performed in the outpatient setting and records brain activity for 24, 48 or 72 hours on a small recording device that the patient takes home. Electrodes are applied to the scalp with a glue-like substance, and the patient is sent home with a diary to record activities and any symptoms while performing normal daily duties. This test is valuable to record paroxysmal events and determine whether or not they are seizures, further characterize the type of seizure or epilepsy and identify EEG abnormalities when the routine EEG is normal.

Continuous EEG monitoring refers to long-term (days to weeks) bedside EEG recording in an acute inpatient (often ICU) setting, with or without simultaneous video recording. Patients are often critically ill, with suspected or known status epilepticus, and continuous EEG (cEEG) is helpful in diagnosis and assessment of the efficacy of treatment. cEEG can also be used to monitor sedation, detect cerebral ischemia, assess the severity of encephalopathy and predict the patient’s prognosis.

Video-EEG monitoring is the simultaneous recording of EEG and videotaped behavior over several days to weeks. This is another type of long-term inpatient monitoring that is usually performed electively in a dedicated epilepsy monitoring unit (EMU). Video-EEG monitoring is helpful in the evaluation of spells when it is not clear if they are epileptic seizures. The EEG activity recorded during a spell can be correlated with the behavior on video to determine if the spell is a seizure. 

Video-EEG monitoring is also used in patients with known epilepsy to characterize the seizure type and to help determine the site of seizure onset in patients who may benefit from surgery. Most often, electrodes are glued to the patient’s scalp, but in some cases electrodes may be surgically placed on the surface of the brain (subdural electrodes) or within the brain substance (intracerebral depth electrodes). EEG can also be recorded directly from the brain during surgery (intraoperative electrocorticography).

Penn State Health Epilepsy Center is recognized by the National Association of Epilepsy Centers as a Level 4 epilepsy center, providing the highest-level medical and surgical evaluation and treatment for patients with complex epilepsy.

The EEG Laboratory at the Medical Center has been accredited by the EEG Laboratory Accreditation Board of ABRET (LAB-EEG) for both routine and long-term monitoring. This means that it has met strict standards and is recognized as a place where patients receive quality diagnostics.

Long-term monitoring provides much more information than a traditional EEG and can help doctors better diagnose and treat patients. It is used:

• When a patient has new-onset seizures
• It is suspected that spells are not seizures
• To characterize the seizure type
• Seizures are occurring in clusters 
• To evaluate intractable epilepsy (patient refractory to two antiepileptic drugs)
• Recurrent seizures or nonconvulsive status epilepticus is suspected as the cause of altered mental status
• To monitor treatment of status epilepticus 
• To monitor sedation and high-dose suppressive therapy  
• To detect cerebral ischemia
• To assess the severity of encephalopathy and prognostication