Perioperative Considerations for Neuroanaesthesia

• Particular attention to posterior column / cervical spine assessment, including range of motion and stability
• Examine relevant imaging of the C-spine


• Patients may have compromised cough and gag reflexes as a result of neuropathology, particularly bulbar weakness
• Respiratory muscle function may be weakened by neuropathology, which may be informally assessed by forced vital capacity at the bedside
• May require formal lung function testing


• Some patients are at higher risk of atelectasis, aspiration and LRTI e.g. due to prolonged immobility or obtunded consciousness
• Pre-operative physiotherapy may be indicated

• Patients may be hypertensive due to disease processes (raised ICP, acromegaly) or their treatments (corticosteroids)
• Baseline BP should be established, as neuropathology may:
• Interrupt BBB
• Affect cerebral autoregulation
• Lead to cerebral vasospasm
• Should establish pre-operatively the desired CPP in lieu of probable ICP


• A pre-operative ECG is a must as intracranial events may lead to dysrhythmia, or coronary spasm secondary to cerebral ischaemia

• Assess and document preoperatively:
• Patient handedness
• GCS
• Pupillary responses
• Neurological deficits
• Relevant neuroimaging e.g. CT, MRI, should be reviewed


• The site/size/nature of a patient's neuropathology will influence aspects of care, including:
• Airway technique
• Positioning
• Need for intra-arterial BP monitoring
• Risk of haemorrhage or cardiovascular instability, intra- or post-operatively
• Risk of seizures or cerebral oedema perioperatively
• Need for higher level care post-operatively


• Patients frequently have epilepsy as a sequelae of their neurosurgical pathology
• Establish which AED their taking
• Be mindful of drug interactions, particularly enzyme induction/inhibition

• Planned use of osmotherapy requires intact renal function
• Disturbance of the HPA may cause sodium disorders
• Hyponatraemia or hypoglycaemia will increase risk of seizures
• Hyperglycaemia can increase cerebral susceptibility to damage from hypoperfusion

• Pre-operative FBC and clotting screen to ensure no coagulopathy prior to neurosurgery
• Patients may be at higher risk of DVT from prolonged immobility or LL weakness
• Yet anticoagulation is often contraindicated in the perioperative period
• Pre-operative assessment of risk and appropriate use of mechanical prophylaxis is vital


• All anti-coagulant and anti-platelet drugs should be stopped prior to surgery, unless there is a pre-agreed risk/balance decision e.g. in conjunction with Cardiology
• NSAIDs should be stopped 5 days prior to surgery

• Intra-operative antibiotic prophylaxis is routine
• Pre-operative pyrexia and raised WCC may arise from non-infective intra-cranial pathology and steroid use
• This complicates the process of establishing/treating infectious aetiologies

• Steroids should be continued perioperatively
• Anticonvulsants may induce liver enzymes and reduce the duration of action of aminosteroid NMBA
• Antiplatelet and anticoagulant drugs will need to be stopped pre-operatively as per protocol
• Sedative pre-medications are generally avoided

• Most cases will require general anaesthesia, and may require specialised techniques such as awake intubation, awake-interval anaesthesia or specialised positioning
• The primary goal is to maintain stable cardiovascular status, which is essential to ensure adequate cerebral and spinal perfusion
• Even short durations of cardiovascular compromise can adversely affect operating conditions and patient outcomes

• AAGBI
• Intra-arterial BP monitoring is regularly required to detect and manage cardiovascular changes; should be at level of external auditory meatus
• Wide bore IV access is prudent; CVC's aren't often required but if so should be subclavian/femoral


• Temperature probe to ensure normothermia
• Urinary catheter, especially if osmotherapy planned or if long surgery
• NG tube if concerns re: impaired bulbar reflexes


• Peripheral nerve stimulator
• At induction to ensure complete paralysis prior to intubation
• To monitor depth of neuromuscular blockade intra-operatively and prevent coughing/straining

• A smooth induction without coughing, straining or major blood pressure fluctuations is required
• Methods to obtund the pressor response to laryngoscopy include:
• Fentanyl (2-3μg/kg) or alfentanil
• TCI remifentanil
• Β-blockers e.g. labetalol 20 - 50mg IV
• IV lidocaine 1.5mg/kg


• Propofol is the most commonly used induction agent, as in addition to familiarity it reduces CBF, CMRO₂ and ICP
• Thiopentone is an acceptable alternative


• Non-depolarising NMBA are most frequently used
• Suxamethonium is relatively contraindicated owing to small increases in ICP with its use


• Reinforced endotracheal tubes should be used; they must be positioned precisely and secured fastidiously:
• To avoid endobronchial migration during head positioning for surgery, as there is limited intra-operative access
• To preclude interruption of cerebral venous drainainge

• No clear superior technique between TIVA or volatile maintenance
• Remifentanil TCI is well-suited to neuroanaesthesia as it:
• Can be rapidly titrated during periods of stimulation
• Facilitates rapid wake-up despite prolonged infusion


• All volatile agents uncouple CBF and CMRO₂
• Increase CBF via cerebral circulatory dilation and impaired autoregulation
• Reduce CMRO₂
• Sevoflurane has the least impact on CBF, with minimal effects below MAC 1.5


• Nitrous oxide should be avoided as it is a potent cerberal vasodilator, and expands air-filled spaces leading to post-operative pneumocephalocoele

• Ensure adequate oxygenation
• Mandatory ventilation rather than spontaneously breathing, to allow manipulation of PCO₂ to 4.5 - 5.0kPa
• Minimal or no PEEP due to effects on ICP


• MAP to a CPP of 60mmHg is generally targeted
• Some procedures require higher CPP, whereas others will require a lower MAP to reduce bleeding in the surgical field
• Patients may have profound bradycardia, especially from dural stretch e.g. tentorium/falx


• If a Mayfield clamp is being used, adequate depth of anaesthesia and analgesia should be on board as pinning is stimulating
• A motionless surgical field is critical and achieved by:
• Remifentanil TCI
• Small boluses or infusion of NMBA guided by a peripheral nerve stimulator


• Avoid dextrose solutions due to combined effect of:
• Free water causing cerebral oedema
• Hyperglycaemia exacerbating brain injury in the hypo-perfused state
• Temperature monitoring and normothermia

• Pinning in the Mayfield clamp is very stimulating
• Need to plan adequate depth of anaesthesia for pinning
• Surgeons may instil scalp blocks to help manage pain from pinning

• Patients should be suctioned under deep anaesthesia
• Routine neuromuscular blockade monitoring and reversal with sugammadex should occur
• Need to ensure adequate BP for haemostasis


• Patients are generally woken and extubated to facilitate early neurological assessment
• If remains anaesthetised, consider ICP monitoring


• A smooth, rapid wake up is necessary to avoid rises in ICP associated with coughing or straining
• Techniques include extubation on a remifentanil infusion or ETT-to-LMA swap

• Airway compromise post-operatively may arise due to:
• Obtunded consciousness
• Impaired airway and gag/cough reflexes following surgery
• Oedema e.g. spinal or carotid surgery

• The incidence of PONV following craniotomy is 50%, and especially common after posterior fossa surgery or foramen magnum decompression
• Vomiting, in addition to its usual negative sequelae, can raise ICP via increased abdominal pressure and systemic hypertension
• A multi-modal approach is required

• Most procedures are not significantly painful post-operatively
• Local anaesthetic infiltration into skin and subcutaneous tissues is often very effective
• Still need to provide adequate analgesia to avoid hypertension, which may cause post-operative bleeding


• The exceptions are those undergoing major intracranial surgery, posterior fossa surgery or foramen magnum decompression, where there is moderate-severe pain
• A multi-modal approach should be used, and long-acting opioids avoided in order to prevent clouding of post-operative neurological assessment

• Neurosurgical patients are at high risk of DVT because of:
• Dehydration from osmotherapy/DI/CSW + preoperative starvation ± reduced oral intake from neuropathology
• Immobility or paralysis
• Pro-coagulant sequelae of TBI
• Pro-thrombotic states e.g. malignancy such as meningioma

• HDU or ICU level care may be required, especially if:
• Cerebral oedema or haemorrhage is possible/expected
• Anticipated post-operative bulbar dysfunction
• Intense neuromonitoring is required