Table 1 Classification and definitions of neurological injury/impairment

A. Cerebrovascular events[17]

Silent

Cerebral infarcts that are observed on magnetic resonance imaging (MRI) scans in the absence of any corresponding, clinically apparent cerebrovascular ischaemic event.

Clinically apparent

Acute episode of a focal or global neurological deficit with at least one of the following: change in the level of consciousness, hemiplegia, hemiparesis, numbness, or sensory loss affecting one side of the body, dysphasia or aphasia, hemianopia, amaurosis fugax, or other neurological signs or symptoms consistent with stroke.

   a. Stroke

Duration of a focal or global neurological deficit ≥ 24 hours; OR <24 hours if available neuroimaging documents a new hemorrhage or infarct; OR the neurological deficit results in death.

i. Ischemic: an acute episode of focal cerebral, spinal or retinal dysfunction caused by infarction of the central nervous system tissue.

ii. Haemorrhagic: an acute episode of focal or global cerebral or spinal dysfunction caused by intraparenchymal, intraventricular, or subarachnoid haemorrhage.

iii. Undetermined: insufficient information to allow categorization as ischemic or haemorrhagic.

i. Disabling stroke (Major): an mRS of 2 or more at 90 days and an increase in at least one mRS category from an individuals pre-stroke baseline.

ii. Non- disabling stroke (Minor): an mRS score of <2 at 90 days or one that does not result in an increase in at least one mRS category from an individual’s pre-stroke baseline.

b. TIA:

   b. TIA

Duration of a focal or global neurological deficit <24 hours, any available neuroimaging does not demonstrate a new haemorrhage or infarct.

Qualifiers

• Exclusion of non-stroke causes for clinical presentation

  o e.g. brain tumour, trauma, infection, hypoglycaemia, peripheral lesion, pharmacological influences etc.

• Determined by or in conjunction with the designated internal medicine specialist or neurologist.

• Diagnosis confirmed by at least one of the following:

   • Neuroimaging procedure (CT scan or MRI brain) and/or

   • Neurologist or neurosurgical specialist.

B. Neurocognitive impairment

   a. POCD

Definition: Deterioration of intellectual function presenting as impaired memory or concentration presenting with temporal association to surgery.

   b. POD

Definition: An acute disturbance of consciousness and a change in cognition with tendency to fluctuate during the course of the day and occurring in patients without some other identifiable aetiology and following normal emergence from anaesthesia.

Qualifiers

• In conjunction with CAM and MoCA assessment tools