Department of Neurophysiology
[Front row sitting left to right: Inder Singh Baghari, Prem Singh Mehra, Dr. M. Gourie-Devi (Chairperson), Dr. Samhita Panda (Consultant), Dr. Kapil Sharma]
[Back row standing from left to right: Sonu, Prem Singh Adhikari, Vijay Sharma, Govind Singh Bisht, Dimple Kapur, Anjana Thakur, Arshiya Fatima, Dr. Hilal]
A. ABOUT THE DEPARTMENT
Neurophysiologic tests are essential to evaluate the function of central nervous system (brain, spinal cord, visual and auditory pathways) and peripheral nerves, neuromuscular junction and muscles. Abnormal tests provide valuable information which aid in diagnosis of a wide range of neurological disorders. The effect of treatment and progress of the illness can also be assessed by repeating the tests.
The diagnostic tests were first established at Sir Ganga Ram hospital in 1984 and during the next three decades, in keeping with the global developments, the department has acquired state of art equipments and has brought improvement in techniques to enhance the diagnostic accuracy.
B. CONSULTANTS AND STAFF
Dr. M. Gourie-Devi is the Chairperson of Department of Neurophysiology. She is also i) Advisor to Indian Council of Medical Research (ICMR) for Neurology Research, ii) Emeritus Professor of Neurology, Institute of Human Behaviour and Allied Sciences, iii) Expert member of Council of Scientific and Industrial Research (CSIR), iv) World Health Organisation (WHO) and v) National Institute of Health (NIH), USA. Research Interests are: Motor Neuron Diseases (MND), Peripheral Neuropathy and Muscle Disorders.
Dr. Samhita Panda is a Consultant in Neurology and Vice-Chairperson of the departments of Clinical Neurophysiology and Sleep Medicine. She has been trained at AIIMS, Delhi and subsequently did a fellowship in Epilepsy and Sleep medicine. She has been trained in the pre-surgical evaluation of patients with refractory epilepsy. Research Interests are: Epilepsy, Sleep and Clinical Neurophysiology.
The department has a Senior Resident and DNB students from the department of Neurology are also posted as per their academic roster. The technical staff strength comprises six technicians presently. An active teaching and training programme for residents in neurology, visiting fellows and technicians has added vibrancy to the department.
C. TEACHING AND TRAINING PROGRAMMES
i) Post graduate students of DNB in Neurology are posted to the department of Neurophysiology for two to three months on rotation, during which they receive intensive training in performance and interpretation of the diagnostic tests and their neurophysiologic basis. In addition, consultants in medicine and paediatrics or physiologists from different regions of the country opt to undergo training in the department on fellowship programme for a few months.
ii) The department of Neurophysiology initiated training programme in 1996 creating technical manpower. Every year, two trainees with science background are recruited for intensive training in all the neurophysiology diagnostic procedures through a ‘hands-on’ program strengthened by lectures by faculty and senior technicians of the department. During the course of 2 years the trainees are familiarized with the equipment, operation of the machines and learn to recognize and rectify commonly encountered artefacts. Preparation of the patient for the procedure, placement of electrodes, stimulation techniques and recording of the results are the essential components of the training programme. The candidates after successful completion of the course are employed as technicians in different hospitals and institutions in the country. Till date 17 technicians have completed training since 1993.
D. NEW PROCEDURES AND INNOVATIONS
Presurgical evaluation of refractory epilepsy
The department of Clinical Neurophysiology in collaboration with the departments of Neurology, Neurosurgery, Neuroradiology, Nuclear medicine and Neuropsychology has recently started a comprehensive presurgical evaluation of refractory epilepsy. This new and innovative programme has been initiated for patients with refractory epilepsy who do not respond to 2 or more anti-epileptic drugs given in adequate doses for 2 years or more. This includes 16-channel Electroencephalography (EEG), neuropsychological evaluation, psychiatric evaluation, visual field charting, MRI of brain with protocol for hippocampal evaluation, video EEG monitoring, functional MRI of brain, interictal and Ictal SPECT of brain and FDG-PET scan of brain.
At the Refractory Epilepsy Board meetings, the results of various investigations along with clinical profile are presented and discussed in depth to assess the feasibility of surgical management. If the data is concordant on presurgical evaluation, surgery is considered. The patient and family members are communicated the decision at the board meeting itself and the patient and family members are encouraged to express their questions, doubts and concerns which are addressed by the board members. The surgically remediable lesions considered are mesial temporal lobe sclerosis, benign tumors such as ganglioglioma, DNET, oligodendroglioma , cortical dysplasia and vascular malformations. Other surgically treatable epilepsies that warrant consideration are Lennox Gastaut Syndrome and Rasmussen’s encephalitis.
The tests done in the department include:
Preoperatively - Long term video EEG monitoring
Ictal SPECT in collaboration with the department of Nuclear Medicine.
Perioperatively- Electrocorticography (ECoG)
Postoperatively- EEGs at fixed intervals in the postoperative period
The Department of Neurophysiology offers diagnostic services for the comprehensive evaluation of diseases of central nervous system and peripheral nervous system.
The diagnostic tests carried out are listed below:-
DETAILS OF PROCEDURES
1. Electroencephalography (EEG)
The electrical activity of brain is recorded by this test. The record is analysed for abnormalities in brain rhythm.
EEG is done in the following conditions:
The EEG is useful for diagnosis, to decide about medication, in monitoring the response to treatment and in long term follow up to evaluate the course of the disease.
Details of Procedure
Recording of electroencephalograph on a digital system
2. Portable EEG
Portable EEG is done for seriously ill patients in the ICU and wards. Recording is done bedside using an ambulatory EEG machine. The report is promptly conveyed to the treating team. Portable EEG is useful in diagnosis of the following conditions, when patient cannot be shifted to the laboratory.
3. Nerve conduction studies (NCS)
Nerve conduction studies is recommended for the following diseases:
Symptoms of nerve involvement
Nerve conduction study in progress
Details of Procedure
Technique of sensory conduction of right median nerve
4. Repetitive nerve stimulation (RNST)
Repetitive nerve stimulation test is a special type of nerve conduction study. Rather than a single electric shock, a brief series of shocks is applied to a motor nerve and responses are recorded from a muscle supplied by that nerve. The study is generally performed before and after brief exercise of the muscle. Serial response amplitudes are recorded. Repetitive nerve stimulation is useful for evaluating myasthenia gravis and other disorders of neuromuscular transmission.
5. Electromyography (EMG)
The EMG test is used to evaluate the status of the muscles, nerves, roots and anterior horn cells. A number of neurological disorders present with weakness or atrophy (thinning) of muscles. Some common disorders are:
The EMG may be done either alone or in combination with nerve conduction studies (NCS) depending on the neurological disorder. Common symptoms of muscle involvement:
Details of Procedure
6. Evoked potentials (EP)
Evoked potential (EP) is the electrical response recorded from brain, spinal cord or peripheral nerve evoked by various external stimuli, such as visual, auditory or somatosensory stimulation. The recording electrodes are placed over the scalp, neck or spine which vary depending on the type of stimulus modality to be tested. The evoked potential provides valuable information about the functional status and diseases affecting vision, hearing and sensory pathways.
6 a. Visual evoked potential (VEP)
VEP provides information regarding conduction in visual pathway from the retina to brain (occipital cortex).
VEP is recommended for following diseases associated with impairment of vision:
Details of Procedure
ERG is performed to evaluate the visual function particularly in the patients suspected to have retinal diseases. It can be performed independently or with VEP.
6b. Brainstem Auditory Evoked Potential (BAER)
This test examines the integrity of auditory pathway through the brainstem. The sound enters the ear canal and stimulates auditory nerve. The electrical impulse travels from auditory nerve through the brainstem to auditory cortex. During testing, the patient hears the repetitive click sound through the earphone.
BAER is recommended for following diseases:
Details of Procedure
Brainstem auditory evoked potential study in progess with graph
6c. Somatosensory evoked potential (SSEP)
This test examines the sensory system from the peripheral nerve to the sensory cortex of brain. Weak electrical stimuli are applied to the peripheral nerve, for example median or ulnar nerve for upper extremity study and tibial nerve for lower extremity study.
SSEP is recommended for following diseases:
Details of Procedure
7. Video-EEG / Long term recording
Video EEG monitoring is undertaken for the patients who have recurrent episodes of loss of consciousness, altered sensorium and seizures. The indications for video EEG are-
The duration of VEEG depends on the clinical disorders, seizure frequency and indication for the video EEG. This can range from 1-3 hours in patients with frequent events (hourly) to 4-5 days in patients with infrequent events and evaluation prior to surgery. One attendant should accompany the patient during the procedure. The EEG along with the patient’s video is recorded simultaneously to evaluate the nature of events.
During events, the clinical onset and semiology of the event is noted. The EEG changes during these events are also noted. The semiology of the clinical events is correlated with the EEG abnormalities. Using this study, the ictal onset zone can be delineated. This is an important component of the presurgical evaluation for medically refractory epilepsy.
Video EEG facilities and expertise is available is only few institutions in the country. The hospital has a well-established video-EEG set-up and more than 400 such procedures have been done.
8. Intraoperative monitoring (IOM)
This is performed in the operation theatre during surgery. This special monitoring is in demand during neurosurgical and orthopaedic procedures to avoid inadvertent damage to the nerves and neurological tissue in the vicinity. Intraoperative neurophysiologic monitoring minimizes neurological morbidity from operative manipulations. It identifies changes in brain, spinal cord, and peripheral nerve function prior to irreversible damage and also localizes anatomical structures, such as peripheral nerves and sensorimotor cortex. Evoked potential monitoring including SSEP, BAER, motor evoked potentials (MEP), and VEP as well as EMG is used during operative cases. IOM helps to differentiate the nerves fibers from connective tissue during surgery particularly in region of cerebellopontine angle and brain stem. The use of this technique helps to prevent complications. Similarly, SSEP is used for monitoring the preservation of spinal cord during scoliosis surgery.Intraoperative scalp EEG can be used to monitor cerebral function during carotid or other vascular surgery. Electrocorticography using subdural electrodes directly over the pial surface can help determine resection margins for epilepsy surgery, and mapping cortical function.