The Department of Intraoperative Neurophysiological Monitoring (IONM) & Clinical Neurophysiology at SIMS Hospital, Chennai, is a specialised super-specialty unit dedicated to real-time monitoring of neural function during complex and high-risk surgeries. As one of the few physician-led IONM programmes in Chennai, the department plays a critical role in protecting the brain, spinal cord, peripheral nerves, and vascular systems during surgery — providing continuous, actionable neurophysiological feedback that enables surgeons to make immediate intraoperative decisions and minimise the risk of neurological injury.
Led by expert neurophysiologists, the department supports the full spectrum of complex neurosurgical, spinal, ENT, oncological, and cardiothoracic procedures, ensuring that critical neural structures are continuously monitored and preserved throughout every stage of surgery. Beyond the operating theatre, the department also offers a comprehensive Clinical Neurophysiology Laboratory for the diagnostic evaluation of neurological disorders, making it a complete centre for both surgical neurophysiology and outpatient neurodiagnostic care in Chennai.
The department actively contributes to international IONM standard-setting initiatives, including the STARD working group, with protocols aligned to global best practices — reflecting its commitment to the highest standards of patient safety and neurophysiological science.
Key Highlights
- Flagship physician-led IONM service delivering real-time protection of critical neural structures during high-risk surgeries
- 24/7 intraoperative neurophysiological support for complex brain, spine, skull base, peripheral nerve, and vascular procedures
- Real-time diagnostic and therapeutic decision support enabling immediate intraoperative course correction
- Advanced expertise in systems neurophysiology and dynamic signal interpretation under anaesthesia
- Multidisciplinary collaboration across Complex Brain Surgery, Advanced Spine Surgery, ENT Surgery, Surgical Oncology, and Cardiothoracic Surgery
- Pioneers in advanced and novel IONM modalities integrated into routine clinical practice
- Active contributor to international IONM standard-setting initiatives through the STARD working group, with globally aligned protocols
- Comprehensive Clinical Neurophysiology Laboratory for diagnosis of complex neurological, neuromuscular, and autonomic conditions
- Specialised IONM expertise in neonatal and paediatric spinal cord malformation surgeries
- Advanced cortical and subcortical mapping for preservation of motor, language, and higher cognitive functions
Comprehensive Services
Intraoperative Neurophysiological Monitoring (IONM) – A full suite of advanced neuromonitoring modalities, customised to the surgical type, stage, and individual risk profile of each patient. All modalities are dynamically integrated intraoperatively to deliver real-time, actionable feedback to the surgical team, enabling maximal safe resection, early detection of neural compromise, and significant reduction in postoperative neurological deficits.
Modalities include Motor Evoked Potentials (MEPs), Somatosensory Evoked Potentials (SSEPs), Continuous and Triggered EMG, D-wave monitoring, Electroencephalography (EEG — raw and processed), Electrocorticography (ECoG), cranial nerve monitoring, pedicle screw testing, nerve root and proximity testing, Brainstem Auditory Evoked Responses (BAERs), reflex monitoring including bulbocavernosus reflex and laryngeal adductor reflex, and advanced cortical and subcortical mapping techniques.
Clinical Neurophysiology Laboratory Services – Comprehensive outpatient neurodiagnostic services for the evaluation of neurological disorders including neuropathies, myopathies, and neuromuscular junction disorders. Services include Single Fibre EMG (SFEMG), Autonomic Function Testing (AFT), Nerve Conduction Studies (NCS), Electromyography (EMG), and Evoked Potentials including Visual Evoked Potentials (VEP), SSEPs, and Brainstem Auditory Evoked Potentials (BAEP).
Pioneering & Specialised IONM Applications – The department is at the forefront of advanced IONM techniques for the most complex and high-risk surgical scenarios, including cortico-bulbar MEPs for facial nerve assessment, extraocular muscle monitoring in skull base surgeries, phrenic nerve monitoring to prevent diaphragmatic dysfunction, cervical pedicle screw monitoring, direct nerve action potentials (DNAP) in peripheral nerve surgery, lateral spread response (LSR) monitoring in microvascular decompression for hemifacial spasm, MEP monitoring in neonates with spinal cord malformations, advanced cognitive mapping for higher cortical function preservation, cuneate nucleus mapping using the SSEP collision technique for medullary procedures, and cortico-cortical evoked potentials (CCEPs) for functional connectivity mapping.
High-Risk Surgical Support – The department provides dedicated IONM support for tumours near the motor cortex and language areas, brainstem and skull base tumours, vestibular schwannoma and cerebellopontine angle lesions, microvascular decompression procedures, complex spinal cord and deformity correction surgeries, spinal cord malformation surgeries in newborns, children, and adults, peripheral nerve surgeries, and select vascular and cardiothoracic procedures with significant neural risk.
Advanced Diagnostic & Treatment Facilities
Intraoperative Monitoring Modalities
• Motor Evoked Potentials (MEPs) and Somatosensory Evoked Potentials (SSEPs) for continuous motor and sensory pathway integrity monitoring
• Continuous and triggered EMG for real-time nerve and muscle activity surveillance
• D-wave monitoring for spinal cord descending motor tract assessment
• Raw and processed EEG and Electrocorticography (ECoG) for cortical activity and seizure monitoring
• Cranial nerve monitoring across multiple nerve groups during skull base and posterior fossa surgery
• Pedicle screw testing and nerve root proximity testing for spinal instrumentation safety
• Brainstem Auditory Evoked Responses (BAERs) for auditory pathway and brainstem integrity
• Reflex monitoring: bulbocavernosus reflex (BCR) for sacral nerve root integrity and laryngeal adductor reflex for airway safety
• Advanced cortical and subcortical mapping for motor, language, and higher cognitive function preservation
Specialised Advanced Techniques
• Cortico-bulbar MEPs (CoMEPs) for intraoperative facial nerve functional assessment
• Extraocular muscle monitoring during orbital and skull base procedures
• Phrenic nerve monitoring to prevent postoperative diaphragmatic dysfunction
• Cervical pedicle screw monitoring for enhanced spinal cord safety
• Direct Nerve Action Potentials (DNAP) in complex peripheral nerve surgery
• Lateral Spread Response (LSR) monitoring in microvascular decompression
• MEP monitoring in neonatal and paediatric spinal cord malformation surgery
• Cuneate nucleus mapping using the SSEP collision technique for medullary procedures
• Cortico-cortical evoked potentials (CCEPs) for functional connectivity and language network mapping
Clinical Neurophysiology Laboratory
• Single Fibre EMG (SFEMG) for neuromuscular junction disorder diagnosis including myasthenia gravis
• Autonomic Function Testing (AFT) for dysautonomia and autonomic neuropathy evaluation
• Nerve Conduction Studies (NCS) and EMG for peripheral nerve and muscle disease assessment
• Evoked Potentials: VEP, SSEP, and BAEP for visual, sensory, and auditory pathway evaluation