Dr Tyagi is known for his anterior cervical and lumbar microsurgical discectomy and craniovertebral junction surgeries .He is an exponent in treating cerebral aneurysm, excision of AVM malformation and all kind of spinal tumor surgeries with results comparable to the best international standards. He is an expert in the spinal instrumentation at all the levels from the cervico occipital to the Lumbosacral regions.
He pioneered functional stereotactic surgery programme at Apollo Hospital New Delhi and has done a large number of Deep Brain Stimulation surgeries and ablative surgeries. He is the first surgeon in India who used Image Fusion technique to localize the targets in the deep part of brain to do functional stereotactic surgeries.
Dr. Sudheer Kumar Tyagi is also known for Frameless Stereotactic Navigation work in cases of epilepsy caused by small lesions which are close to eloquent areas of brain. Stereotactic Radiosurgery (SRS) is another area in which he has done the largest number of cases at the Apollo Hospital New Delhi. He is actively involved in neurosurgical training and research work at Apollo Hospitals New Delhi