Neurosurgery, or neurological surgery, is the medical specialty concerned with the prevention, diagnosis, surgical treatment, and rehabilitation of disorders which affect any portion of the nervous system including the brain, spinal cord, peripheral nerves, and extra-cranial cerebrovascular system.
General neurosurgery involves most neurosurgical conditions including neuro-trauma and other neuro-emergencies such as intracranial hemorrhage. Most level 1 hospitals have this kind of practice.

Specialized branches have developed to cater to special and difficult conditions. These specialized branches co-exist with general neurosurgery in more sophisticated hospitals. To practice advanced specialization within neurosurgery, additional higher fellowship training of one to two years is expected from the neurosurgeon. Some of these divisions of neurosurgery are:

• vascular neurosurgery and endovascular neurosurgery
• stereotactic neurosurgery, functional neurosurgery, and epilepsy surgery (the latter includes partial or total corpus callosotomy – severing part or all of the corpus callosum to stop or lessen seizure spread and activity, and the surgical removal of functional, physiological and/or anatomical pieces or divisions of the brain, called epileptic foci, that are operable and that are causing seizures, and also the more radical and very, very rare partial or total lobectomy, or even hemispherectomy – the removal of part or all of one of the lobes, or one of the cerebral hemispheres of the brain; those two procedures, when possible, are also very, very rarely used in oncological neurosurgery or to treat very severe neurological trauma, such as stab or gunshot wounds to the brain)
• oncological neurosurgery also called neurosurgical oncology; includes pediatric oncological neurosurgery; treatment of benign and malignant central and peripheral nervous system cancers and pre-cancerous lesions in adults and children (including, among others, glioblastoma multiforme and other gliomas, brain stem cancer, astrocytoma, pontine glioma, medulloblastoma, spinal cancer, tumors of the meninges and intracranial spaces, secondary metastases to the brain, spine, and nerves, and peripheral nervous system tumors)
• skull base surgery
• spinal neurosurgery
• peripheral nerve surgery
• pediatric neurosurgery (for cancer, seizures, bleeding, stroke, cognitive disorders or congenital neurological disorders)

Neuroradiology plays a key role not only in diagnosis but also in the operative phase of neurosurgery.

Neuroradiology methods are used in modern neurosurgery diagnosis and treatment. They include computer assisted imaging computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), magnetoencephalography (MEG), and stereotactic radiosurgery. Some neurosurgery procedures involve the use of intra-operative MRI and functional MRI.

In conventional open surgery the neurosurgeon opens the skull, creating a large opening to access the brain. Techniques involving smaller openings with the aid of microscopes and endoscopes are now being used as well. Methods that utilize small craniotomies in conjunction with high-clarity microscopic visualization of neural tissue offer excellent results. However, the open methods are still traditionally used in trauma or emergency situations.

Microsurgery is utilized in many aspects of neurological surgery. Microvascular techniques are used in EC-IC bypass surgery and in restoration carotid endarterectomy. The clipping of an aneurysm is performed under microscopic vision. minimally-invasive spine surgery utilizes microscopes or endoscopes. Procedures such as microdiscectomy, laminectomy, and artificial disc replacement rely on microsurgery.

Using stereotaxy neurosurgeons can approach a minute target in the brain through a minimal opening. This is used in functional neurosurgery where electrodes are implanted or gene therapy is instituted with high level of accuracy as in the case of Parkinson's disease or Alzheimer's disease. Using the combination method of open and stereotactic surgery, intraventricular hemorrhages can potentially be evacuated successfully.[12] Conventional surgery using image guidance technologies is also becoming common and is referred to as surgical navigation, computer assisted surgery, navigated surgery, stereotactic navigation. Similar to a car or mobile Global Positioning System (GPS), image guided surgery systems, like Curve Image Guided Surgery and StealthStation, use cameras or electromagnetic fields to capture and relay the patient’s anatomy and the surgeon’s precise movements in relation to the patient, to computer monitors in the operating room. These sophisticated computerized systems are used before and during surgery to help orient the surgeon with three-dimensional images of the patient’s anatomy including the tumor.

Minimally invasive endoscopic surgery is commonly utilized by neurosurgeons when appropriate. Techniques such as endoscopic endonasal surgery are used in pituitary tumors, craniopharyngiomas, chordomas, and the repair of cerebrospinal fluid leaks. Ventricular endoscopy is used in the treatment of intraventricular bleeds, hydrocephalus, colloid cyst and neurocysticercosis. Endonasal endoscopy is at times carried out with neurosurgeons and ENT surgeons working together as a team.

Repair of craniofacial disorders and disturbance of cerebrospinal fluid circulation is done by neurosurgeons who also occasionally team up with maxillofacial and plastic surgeons. Cranioplasty for craniosynostosis is performed by pediatric neurosurgeons with or without plastic surgeons.

Neurosurgeons are involved in stereotactic radiosurgery along with radiation oncologists in tumor and AVM treatment. Radiosurgical methods such as Gamma knife, Cyberknife and Novalis Radiosurgery are used as well.

Endovascular Neurosurgery utilize endovascular image guided procedures for the treatment of aneurysms, AVMs, carotid stenosis, strokes, and spinal malformations, and vasospasms. Techniques such as angioplasty, stenting, clot retrieval, embolization, and diagnostic angiography are endovascular procedures.

A common procedure performed in neurosurgery is the placement of Ventriculo-Peritoneal Shunt (VP Shunt). In pediatric practice this is often implemented in cases of congenital hydrocephalus. The most common indication for this procedure in adults is Normal Pressure Hydrocephalus (NPH).

Neurosurgery of the spine covers the cervical, thoracic and lumbar spine. Some indications for spine surgery include spinal cord compression resulting from trauma, arthritis of the spinal discs, or spondylosis. In cervical cord compression, patients may have difficulty with gait, balance issues, and/or numbness and tingling in the hands or feet. Spondylosis is the condition of spinal disc degeneration and arthritis that may compress the spinal canal. This condition can often result in bone-spurring and disc herniation. Power drills and special instruments are often used to correct any compression problems of the spinal canal. Disc herniations of spinal vertebral discs are removed with special rongeurs. This procedure is known as a discectomy. Generally once a disc is removed it is replaced by an implant which will create a bony fusion between vertebral bodies above and below. Instead, a mobile disc could be implanted into the disc space to maintain mobility. This is commonly used in cervical disc surgery. At times instead of disc removal a Laser discectomy could be used to decompress a nerve root. This method is mainly used for lumbar discs. Laminectomy is the removal of the Lamina portion of the vertebrae of the spine in order to make room for the compressed nerve tissue.