Routine EEG, Ambulatory EEG, Long term VDO EEG monitoring
Electroencephalogram (EEG) or brain wave test is a test to detect brain electrical activities or brain waves. The test is painless, non invasive, can be performed even in newborn baby. The test is performed by an EEG technician. Routine EEG is last about 45 minutes to 1 hour ; The test can be extended to 24 hours as either in or out patient setting so call “ambulatory”. Occasionally, EEG brain signal can be recorded along with VDO capture or “VDO EEG monitoring” for a period of days or even weeks (Long term monitoring).   EEG is used to diagnose the seizure disorders, to evaluate altered consciousness, confusion, sleep problems, dementia, or any disturbances of brain functions.  And it is used to confirm brain death, to determine the severity and follow up in comatose patient.

Nerve Conduction Studies (NCS)
Electromyography (EMG)
Muscular weakness may be caused by either disorders of muscle and/or nerve or neither of them. Nerve conduction studies (NCS) and Electromyography (EMG) helps neurologists to narrow the problems; are used to diagnose disorder of nerve and muscle.  NCS is a test to study the nerve impulse. It is not painful, but uneasy and discomfort procedure. The skin surface over the studied nerve will be stimulated using electrical impulse while the response mostly muscle twitching are recorded. Patient will feel as an electrical shock. It is the standard and safe procedure. The stimulations can be performed over the nerve length (either near the stimulated muscle or further away). The nerve conduction velocity and amplitude of the response can be obtained from the studies; which directly tell how well being of the studies nerve. NCS provides the nerve well being.  NCS is sensitive test; however has some limitations. Only the large diameter nerve fibers (vibration, touch sensation) can be studied by NCS. Small nerve fibers (pain, temperature sensation) needs another test that more sensitive to pain and temperature or Quantitative Sensory Testing (QST).

EMG is slightly painful and lengthy procedure. It often followed NCS. The procedure required special needle to exam or insert into the studied muscles; like acupuncture. There is no electrical stimulation required; however muscle electrical activities will be recorded through special needle at sampling muscle. The signal then be recorded; analyzed by advanced diagnostic machine. After the test, patient may feel muscle pain at puncture sites. 

Quantitative Sensory Testing (QST)
QST is used to diagnose the disorder of small fiber nerve. It is painless, well-developed psychophysical methods to detect, characterize and quantitate sensory abnormalities.  Patient’s threshold to warm, cold, vibration will reflect the degree of nerve damage. Nerve damage impairs sensory perceptions eg pain and temperature (warm or cool). Scientific way to quantify the degree and type of impairments are possible by using Quantitative Sensory Testing (QST). This test is performed by computer aided sensory evaluator to study patients’ ability to precept various sensations or patient’s sensory threshold for temperature (warm and cool) and/or vibratory perceptions.  Type and degree of nerve impairment then can be quantified.  The devices (thermal, vibratory stimulator) will attach to patient’s skin areas over face, hand, foot. Patient then will press the button whenever he or she feels “warm, cold or vibrate”. 

Somatosensory Evoked Potentials (SEPs)
Brainstem Auditory Evoked Potentials (BAEPs)
Visual Evoked Potentials (VEPs)
Motor Evoked Potentials (MEPs)

All studies i.e.  AEPs VEPS, SEPs, and MEPs are safe and painless studies. They are motor and sensory nerves tests helping neurologist to localize or answer “where is the problem?” and also monitor the lesion in the long term. Abnormalities of studies indicate underlying pathology along either sensory or motor pathway within the nervous system.  Motor and Sensory systems can be studied by evoked potentials (EPs). 

For sensory system, brain perceives various sensory stimuli ( sound or auditory, mechanic, electrical or somatosensory, light spectrum or visual) though sensory organs i.e.  ear, skin and eye, which then conveys the signals up or ascending  to the correspondent areas in the brain.  EPs are the electrical signals generated by the nervous system along the way eg. at cortex, brainstem, spinal cord or plexus,  in response to stimuli i.e.  auditory, visual, and sensory stimuli.  EPs are then called “auditory, visual and somotosensory evoked potentials (AEPs, VEPs, SEPs) respectively”. In SEPs, sensory nerves in arm i.e.  median, ulnar nerves  or in leg i.e. tibial, personal nerves will be stimulated by electrical stimuli;  while the nervous system response to stimuli; it will generate the electrical signals that can be recorded at arm, neck and scalp.  In AEPs, patient will hear the “click sound” stimuli through headphone; while the electrical signals will be recorded from the scalp. In VEPs, the responses are recorded from scalp over visual area while patient look at the monitor screen or “flash, reversal checker pattern” stimuli.

For motor system, on the other hand, once brain orders either arm or leg to move, the signal from correspondent cortex will travel down or descending through brainstem, spinal cord, nerve and then to muscle. If we stimulate correspondent cortex by either electrical or magnetic pulse, the cortical signal will follow motor pathway as above mentioned down to muscle. Once muscle twitch, it generate electrical signal so called “motor evoked potentials (MEPs).   For MEP studies, facial , arm , leg muscles can be studied in healthy live patient. Cortical areas for face, arm, leg (Transcranial) or spinal root or nerve to particular muscles can be stimulated by using strong magnetic impulse generated by transcranial magnetic stimulator (TMS).

Transcranial Magnetic Stimulator (TMS)
TMS is a medical instrument that using electrical current to produce the strong magnetic field from the coil of wire.  Because of magnetic field’s physical property, it can penetrate and pass through tissues eg scalp, skull, bone, and brain tissue without losing of field strength. Magnetic field itself will induce electrical current inside the brain tissue; which mean “brain tissue can be stimulated by magnetic fields”.  TMS then become a powerful tool in research, diagnostic, and even treatment of brain disorder.  For diagnostic purpose, by stimulating particular brain area with TMS, it help neurologist to localize where the problem is. For treatment, TMS has been used to treat drug resistant mental illness eg depression, mania, auditory hallucination, posttraumatic stress disorder as alternative to electroconvulsive therapy and headache, migraine, poststroke depression.   It is safe and painless procedure. 

Doppler Neurovascular Laboratories:
Routine Transcranial Doppler (TCD)
Bilateral Transcranial Doppler (TCD) monitoring
Functional test:  CO2 vasoreactivity test
Emboli Detection

High Intensity Transient Signals (HITS) test with and without IV microbubble injections.

Transcranial doppler (TCD) ultrasound is a safe, painless, reliable, and inexpensive way for measuring cerebrovascular blood flow, which reflect how well blood vessels esp intracranial are. Patient’s cranial blood vessels will be studied by pulses of ultrasound, at frequencies around 2 MHz by using a handheld transducer towards the vascular formations in the base of the skull. The frequency shift or the doppler effect of the reflected sound indicates the velocity of the reflecting matter.  Images then can also be reconstructed.  This test is useful in evaluation of stroke patient. This test can be performed as the diagnostic test or monitoring in neurointensive care.

Sleep Laboratories:
Routine overnight polysomnographic diagnostic study (PSG)
CPAP titration study
Split night study
Multiple Sleep Latency Test (MSLT) or Nap Study

A sleep study, also called a polysomnogram (PSG), is a test to records how well your sleep. You need to be in the hospital bed.  The test will monitor your sleep stages, body position, blood oxygen levels, respiratory events, muscle tone, heart rate, and amount of snoring and general sleep behavior during the night. The sleep technician will hook you to various instrument and also attend you sleep. Routine diagnostic study takes about 6-8 hours for one study per night.  In some situation; the study can be done without the presence of sleep technician.  Based on your study’s result, you might need to return for the second study. For example, in case of sleep apnea, on the second night the treatment as Continuous Positive Airway Pressure or CPAP, a device that gently blows air into your nasal passages to keep the airway open while you are asleep will be prescribed in order to find the optimal pressure for you or CPAP titration study.  However, because of limited financial resource, you may participate in a "split-night" test, in which half the night will be used to diagnose your sleep problem, and the other half will be used to treat the problem by using CPAP.

The same sleep study can be done during the day time on the next following after routine diagnostic study.  Patient will take 5 naps during the day.
This study or so call “Multiple Sleep Latency Test (MSLT)” or Nap test can tell how sleepy you are.

Autonomic Studies:

RR interval analysis
Sympathetic Skin Responses

The autonomic division of the nervous system is a special division that serves to regulate many basic visceral housekeeping functions eg. HR, BP, gastrointestinal, bladder, sweat. The autonomic nervous system is involved by several disease process eg . stroke, neurodegenerative disease, neuropathy, drug or toxin. Among those, DM polyneuropathy is one of the commonest.  To assess autonomic functions, tests can be broadly categories in to 3 main areas: to assess cardiacvagal innervation, to assess adrenergic function and to assess sudomotor function.   RR interval and sympathetic skin responses are test to evaluate cardiacvagal function and sudomotor function respectively. The tests are well established, non invasive, painless procedure.   For RR interval analysis; the patient’s heart rate, electrocardiogram will be analyzed under various physiologic conditions eg during deep breathing, or standing. For sympathetic skin response, patients’ sweat function as reflected by skin conductance under sympathetic cholinergic function will be assessed by using electrical stimuli over correspondent skin area.