The NIH Stroke Scale (NIHSS) was developed by the National Institute of Neurological Disorders and Stroke to provide a standardised, reproducible assessment of neurological deficit severity in acute stroke patients. Originally published in 1989, it has become the global standard for stroke severity quantification, used in clinical trials, treatment eligibility determinations (particularly for IV thrombolysis and mechanical thrombectomy), and outcome prediction. The scale consists of 15 items assessing consciousness, gaze, visual fields, facial palsy, limb motor function, ataxia, sensation, language, dysarthria, and extinction.

The Mini-Mental State Examination (MMSE) was developed by Folstein, Folstein, and McHugh in 1975 and became the most widely administered cognitive screening instrument in the world, used in over 300 million assessments. It assesses orientation, registration, attention/calculation, recall, and language/visuospatial function. Despite being largely superseded by the MoCA for MCI detection, the MMSE remains in widespread clinical use for tracking dementia severity, monitoring treatment response, and determining decision-making capacity. The MMSE is copyrighted by Psychological Assessment Resources (PAR) and technically requires a license for clinical use.

The Glasgow Coma Scale (GCS) was developed by Graham Teasdale and Bryan Jennett at the University of Glasgow in 1974 to provide an objective, standardised method of measuring consciousness in patients with traumatic brain injury. It quickly became the universal standard for neurological observation and is used in trauma, neurosurgery, neurology, and intensive care. The scale assesses three components: eye opening, verbal response, and motor response, with a total score ranging from 3 (deep coma or death) to 15 (fully awake). The Paediatric GCS (pGCS) modifies the verbal and motor components to account for age-appropriate responses in infants and young children.