Craniotomy — How It Works, Benefits & Recovery — Procedure Guide, Recovery & Risks | MyMedicPlus

A craniotomy is a neurosurgical procedure in which a temporary section of skull bone (bone flap) is removed to gain direct access to the brain for diagnosis or treatment of intracranial pathology. The procedure is distinguished from craniectomy, in which the bone flap is not immediately replaced — craniectomy is reserved for cases requiring decompression from severe cerebral swelling. In craniotomy, the bone flap is replaced and secured with titanium plates and screws at the end of the procedure. Craniotomy enables treatment of brain tumours, unruptured and ruptured intracranial aneurysms, subdural and epidural haematomas, cerebral abscesses, arteriovenous malformations (AVMs), cavernomas, cortical epilepsy foci, and hydrocephalic shunt placement. Modern craniotomy employs operating microscopes providing 4–40× magnification, neuronavigation (MRI/CT-guided stereotactic mapping), intraoperative neuromonitoring with evoked potentials, intraoperative MRI at specialist centres, and fluorescence guidance. The size and location of the bone flap are planned using pre-operative imaging to minimise brain retraction and provide adequate exposure. Approximately 15,000 craniotomies are performed annually in England for brain tumour resection alone. The procedure is carried out by fellowship-trained neurosurgeons at specialist tertiary neurosurgical centres equipped with intraoperative MRI, neuronavigation, and neurophysiological monitoring capabilities.

Craniotomy is indicated across a broad spectrum of intracranial pathologies. Brain tumour resection — including gliomas, meningiomas, brain metastases, pituitary macroadenomas (via transcranial approach), and posterior fossa tumours — is the most common indication. Intracranial aneurysm clipping is performed for both ruptured aneurysms causing subarachnoid haemorrhage and unruptured aneurysms meeting treatment criteria based on size and morphology. Emergency craniotomy for evacuation of an acute subdural haematoma (ASDH) or epidural haematoma (EDH) is life-saving surgery performed within 4 hours of clinical deterioration. Intracerebral haemorrhage evacuations are selective, based on clot volume, location, and clinical course. Cerebral abscess drainage for suppurative infections unresponsive to antibiotics requires surgical decompression. Epilepsy surgery (lesionectomy, temporal lobectomy, corpus callosotomy) is performed in centres specialising in functional neurosurgery. AVM and cavernoma resections are elective procedures to prevent rebleed. Awake craniotomy is specifically used for tumours or epilepsy foci in eloquent cortex (language, motor, or sensory areas).

The patient's head is secured in a three-pin Mayfield frame to provide absolute rigidity throughout surgery. Surgical planning uses neuronavigation registration, fusing pre-operative MRI and CT data, to accurately localise the craniotomy over the target lesion. Under general anaesthesia (or with the patient awake for eloquent cortex lesions), the scalp is incised in a carefully planned fashion, reflected with clips, and the temporalis muscle elevated or split as required. A high-speed craniotome (pneumatic or electric drill) creates burr holes at the planned corners; the bone flap is cut between them and lifted. The dura mater is opened in a cruciate or curved pattern and reflected. Brain parenchyma is approached through the least eloquent corridor using microsurgical technique — bipolar diathermy, ultrasonic aspiration (CUSA), and suction. Intraoperative neuromonitoring (motor evoked potentials, somatosensory evoked potentials) alerts the surgeon to impending neurological injury. After completing the surgical objective, haemostasis is achieved, the dura closed watertight with sutures and dural substitute, the bone flap repositioned, secured with miniature titanium plates, and the scalp closed in layers. Closure includes a subgaleal drain. Total operative time ranges from 2–8 hours depending on complexity and pathology. Operative duration ranges from 3–4 hours for straightforward tumour resections to 8–12 hours for skull base surgery or complex aneurysm procedures.

Craniotomy outcomes depend on the underlying pathology and patient factors. Aneurysm clipping achieves 85–92% complete occlusion confirmed by post-operative catheter angiography; rebleed rates from clipped aneurysms are below 1% per year. Meningioma gross total resection (Simpson Grade I–II) achieves 90–95% 10-year local control without adjuvant therapy. Subdural haematoma evacuation in patients presenting with GCS 10–13 achieves good neurological recovery in 60–75% of cases. Epilepsy surgery achieves seizure freedom (Engel Class I) in 60–80% of temporal lobe cases and 40–60% of extratemporal lesionectomies. AVM resection achieves cure (obliteration of nidus) in 90–95% of accessible cases. Brain tumour surgery with maximal safe resection, as a component of multimodal treatment, improves survival and quality of life for most histological types. Stereoelectroencephalography (SEEG) implantation and responsive neurostimulation are emerging craniotomy-adjacent techniques for refractory epilepsy.

Craniotomy carries risks that are directly related to the brain region operated upon and the nature of the underlying pathology. New or worsened neurological deficit — motor weakness, aphasia, visual field defect, memory impairment — occurs in 5–20% of patients depending on lesion eloquence; many deficits improve over 3–6 months with rehabilitation. Surgical site infection (wound or bone flap) affects 2–4% and may require bone flap removal. Intracerebral or subdural haematoma requiring reoperation occurs in 2–5%. Cerebral oedema is managed with perioperative dexamethasone (4–8 mg four times daily tapered over 7–14 days). CSF leak through the wound or via nose/ears may require lumbar drainage or reoperation. Seizures occur in up to 20% of patients with supratentorial pathology and require anticonvulsant treatment. DVT and pulmonary embolism risk is elevated from immobility and prolonged surgery; pneumatic compression stockings and early mobilisation are standard. Hydrocephalus requiring ventriculoperitoneal shunt insertion occurs in 5–15% of posterior fossa craniotomies. Operative mortality at specialised neurosurgical centres is below 1–2% for elective supratentorial procedures.

Post-operatively, patients are nursed in a neurosurgical ICU or high-dependency unit for 24–48 hours with continuous monitoring of GCS, pupil responses, blood pressure, and oxygen saturation. The head of the bed is elevated 30 degrees to reduce intracranial pressure. Dexamethasone tapers over 7–14 days. Prophylactic anticonvulsants are continued for at least 7–10 days and reassessed based on pathology and EEG. Analgesia combines regular paracetamol, codeine, and judicious use of NSAIDs, avoiding opioids that cloud neurological assessment. MRI brain with gadolinium is performed within 24–72 hours to assess resection extent and detect haemorrhage. Hospital stay is typically 3–7 days for supratentorial procedures; 5–10 days for posterior fossa. Staples are removed at 10–14 days. Neurological rehabilitation — physiotherapy, speech therapy, occupational therapy — begins during admission and continues as outpatient. Full neurological recovery takes 6–12 weeks for most patients. Return to driving requires compliance with national regulations regarding seizure-free periods — typically 6–12 months for intracranial pathology. Oncology and outpatient neurosurgery follow-up is planned before discharge.