Study guide
2.1 Neurological Examination in the ICU
ABIM Neurocritical Care Subspecialty Certification Exam
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1 Introduction & Exam Overview
1.1 Current Exam Facts 1.2 Eligibility, Practice Pathway, and the IM Training Route 1.3 Format, Scoring, Pearson VUE, and Score Reports 1.4 How to Use This Independent Study Guide
2 ICU Neurologic Exam, Cerebral Physiology, and CSF
2.1 Neurological Examination in the ICU 2.2 Cerebral Physiology, ICP, CBF, and Autoregulation 2.3 CSF Physiology
3 Core Neuropharmacology
3.1 Osmotic Agents 3.2 Anti-Seizure Drugs 3.3 Anesthetics, Sedatives, Analgesia, and Paralytics 3.4 Antihypertensives, Vasopressors, and Inotropes
4 Reperfusion Drugs, Airway, and Ventilation
4.1 Thrombolytics, Anticoagulants, and Antiplatelets 4.2 Reversal of Anticoagulation After Acute Hemorrhage 4.3 Airway Management and Tracheostomy 4.4 Mechanical Ventilation
5 Hemodynamics and Shock
5.1 Hemodynamic Monitoring 5.2 IABP, Temporary VADs, LVAD, and ECMO 5.3 Diagnosis and Management of Shock
6 Nutrition, Temperature, and ICU Prophylaxis
6.1 Nutrition (01.J) 6.2 Temperature Control (01.K) 6.3 ICU Prophylaxis, Delirium, and Early Mobility (01.L)
7 General Trauma
7.1 Emergency Evaluation of Polytrauma, Chest, and Abdominal Trauma 7.2 Long-Bone Fractures and Fat Embolism 7.3 Burns, Electrical Injury, and Hanging/Strangulation
8 Pulmonary Critical Care
8.1 Pulmonary Physiology and ARDS (01.N.1–2) 8.2 PE, Pneumonia, and Pulmonary Edema (01.N.3, 7–8) 8.3 COPD, Asthma, PAH, and Bronchoscopy Basics (01.N.4–6, 9)
9 Cardiovascular Critical Care
9.1 Cardiovascular Physiology, Stress Cardiomyopathy, ACS, and Valves 9.2 Arrhythmias and Pacing 9.3 Acute Aortic Dissection and Cardiac Ultrasound
10 Renal and Infectious Disease
10.1 AKI, RRT, and Renal Drug Dosing 10.2 Acid-Base and Electrolyte Disorders 10.3 Severe Sepsis, Septic Shock, and Infective Endocarditis 10.4 Antimicrobial Use and Infection in the Immunosuppressed
11 Endocrine and Salt-Water Disorders
11.1 Pituitary Apoplexy, DI, and Panhypopituitarism (01.R.1–4) 11.2 SIADH and Cerebral Salt Wasting (01.R.5–6) 11.3 Thyrotoxicosis, Myxedema, Adrenal Crisis, and Dysglycemia (01.R.7–9)
12 Gastrointestinal Critical Care
12.1 GI Physiology, Acute Abdomen, Bleed, Ileus, and Perforation (01.S.1–5) 12.2 Mesenteric Ischemia and Abdominal Compartment Syndrome (01.S.6–7) 12.3 Fulminant Liver Failure, Cirrhosis Decompensation, and Hepatic Dosing (01.S.8–10)
13 Hematologic Disorders
13.1 Anemia, Transfusion, Thrombocytopenia, Coagulopathy, and DIC (01.T.1–4) 13.2 VTE in the Neuro ICU (01.T.5) 13.3 Chemo/Immune, SCT, CAR-T, Sickle Cell, and TMA (01.T.6–10)
14 Neuroimaging
14.1 CT of Brain and Spine 14.2 MRI and CT/MR Perfusion 14.3 Noninvasive Angiography and Catheter Angiography
15 EEG, EMG, and CSF Analysis
15.1 EEG, Standard and Processed (02.B) 15.2 Basic EMG Interpretation (02.G) 15.3 CSF Analysis (02.H)
16 ICP, TCD, and Multimodality Monitoring
16.1 ICP Monitoring (02.C) 16.2 Transcranial Doppler (02.D) 16.3 Brain-Tissue Oxygen and Multimodality Monitoring (02.E–F)
17 Brain Death and Bedside Procedures
17.1 Brain Death Prerequisites and Clinical Exam (02.I) 17.2 Apnea Testing and Ancillary Studies (02.I) 17.3 Vascular Access, Thoracic Echo, and Lung Ultrasound (02.J–L)
18 Coma, Anoxia, and Intracranial Hypertension
18.1 Coma and Other States of Altered Consciousness (03.A) 18.2 Global Anoxia-Ischemia and Post-Resuscitation Encephalopathy (03.A.1) 18.3 Toxidromes, ICU Delirium, and Hypertensive Encephalopathy (03.A.2–4) 18.4 Intracranial Hypertension as a Disease State (03.B)
19 Acute Ischemic Stroke
19.1 IV Reperfusion Therapy (03.C.3) 19.2 Mechanical Thrombectomy Windows and Imaging Selection (03.C.3) 19.3 Malignant Hemispheric Infarction and Basilar Artery Occlusion (03.C.1–2)
20 Intraparenchymal Hemorrhage
20.1 Intracerebral Hematoma (03.D.1) 20.2 Cerebellar Hematoma (03.D.2) 20.3 Intraventricular Hemorrhage (03.D.3)
21 SAH, CVST, and Spinal Cord Infarction
21.1 Aneurysmal Subarachnoid Hemorrhage (03.E.1) 21.2 Non-Aneurysmal SAH (03.E.2) 21.3 Cerebral Venous Sinus Thrombosis (03.F) 21.4 Spinal Cord Infarction (03.G)
22 Vascular Anomalies and Traumatic Brain Injury
22.1 Unruptured Aneurysm, Cavernoma, AVM, and Dural AVF (03.H) 22.2 Diffuse Axonal Injury and Cerebral Contusions (03.I.1–2) 22.3 Epidural Hematoma, Subdural Hematoma, and Penetrating Injury (03.I.3–4, 7) 22.4 Arterial Dissection and Carotid-Cavernous Fistula (03.I.5–6)
23 Spine, Hydrocephalus, and CNS Infection
23.1 Spinal Cord Injury, Central Cord, and Neurogenic Shock (03.J) 23.2 Unstable Spine Fractures (03.K) 23.3 Hydrocephalus and CSF Diversion (03.L) 23.4 Acute CNS Infections (03.M)
24 Seizures and Neuromuscular Emergencies
24.1 Status Epilepticus and Seizures (03.N) 24.2 Guillain-Barré Syndrome (03.O.1) 24.3 Myasthenic Crisis (03.O.2) 24.4 Motor Neuron Disease, Acute Myopathies, Rhabdomyolysis, and CINM (03.O.3–6)
25 Inflammatory Disease, Neuro-Oncology, and Special Populations
25.1 Fulminant Demyelinating Diseases (03.P) 25.2 Autoimmune Encephalitis and Acute Autonomic Hyperactivity (03.Q–R) 25.3 Neuro-Oncology and Treatment Complications (03.S) 25.4 Pregnancy/Post-Partum, Post-Transplant, and Pediatric Patients (03.T–U)
26 Neurosurgical and Perioperative Complications
26.1 Postoperative Seizures, Hemorrhage, Ischemia, and Hyperperfusion (04.A, C, D, H) 26.2 Infection, CSF Leak, and Pneumocephalus (04.B, E, F) 26.3 Complications of EVD and Lumbar Drain (04.G, I)
27 Ethics, Prognostication, and Organ Donation
27.1 Communication, Decision-Makers, Advance Directives, and DNR (05.A, B, G) 27.2 Uncertainties of Prognostication and the Self-Fulfilling Prophecy (05.C) 27.3 Palliative Care, Withdrawal, Withholding, and Futility (05.D–F) 27.4 Donation After Cardiac Death and Care of the Organ Donor (05.H–I)
2.1 Neurological Examination in the ICU
Key Takeaways Explain This Topic AI
The Glasgow Coma Scale sums Eye 1–4, Verbal 1–5, and Motor 1–6 for a total of 3–15; GCS of 8 or less is the conventional severe-injury cut used to protect the airway.
The FOUR score grades eye, motor, brainstem reflexes, and respiration (each 0–4, total 0–16) and remains usable when the patient is intubated.
A unilateral fixed dilated pupil is the classic bedside warning of uncal herniation from ipsilateral oculomotor-nerve compression.
Sedation, hypothermia, neuromuscular blockade, and metabolic encephalopathies can mimic brainstem failure and must be excluded before the exam is trusted.
NIHSS ranges from 0 to 42 and is a stroke deficit scale, not a substitute for a coma or brainstem examination.
Last updated: September 2026
Neurological Examination in the ICU
Quick Answer: GCS sums Eye 1–4, Verbal 1–5, and Motor 1–6 (total 3–15 ); GCS ≤8 is the conventional severe cut used to protect the airway. The FOUR score adds brainstem reflexes and respiration and remains usable when the patient is intubated. NIHSS runs 0–42 . A unilateral fixed dilated pupil is the classic uncal-herniation warning. Subtract sedation, hypothermia, neuromuscular blockade, and metabolic failure before you trust a silent brainstem.
The ICU neurologic exam is how you decide whether the brain is worsening in minutes, not how you write a clinic note. On the ABIM Neurocritical Care examination, stems often give a pupil change, a motor pattern, or a "GCS of 7T" and ask what the finding localizes to, or whether the exam is even valid. Independent ExamFinch teaching in this section covers neurologic examination topics listed under Principles of neurocritical care in the ABPN Content Specifications. This guide is not an ABIM or ABPN product.
Glasgow Coma Scale: E4 V5 M6
The Glasgow Coma Scale (GCS) rates three behaviors. Record the best response in each column and report subscores , not only the total.
- Component 1 2 3 4 5 6
- Eye (E) None To pressure To sound Spontaneous — —
- Verbal (V) None Sounds Words Confused Oriented —
- Motor (M) None Extension Abnormal flexion Withdrawal Localizes Obeys
The theoretical floor is 3 and the ceiling is 15 . Severe brain injury is conventionally GCS ≤8 , which is also the usual trigger to protect the airway if the low score is from brain failure rather than from a paralytic or a recently given induction dose. Moderate is often taught as 9–12 and mild as 13–15; those bands are descriptors, not treatment algorithms.
Worked scoring: a trauma patient opens eyes only to trapezius squeeze ( E2 ), groans without words ( V2 ), and pulls the examiner's hand off the supraorbital ridge ( M5 ). GCS = 2 + 2 + 5 = 9 . If the same patient is intubated and makes no sound, verbal is scored 1 and annotated T (for example GCS 8T if E2 V1T M5). Do not invent a "normal verbal of 5" for a silent endotracheal tube.
GCS does not test pupils, corneal reflexes, or breathing pattern. Two patients with a total of 8 can have completely different brainstem exams. A falling motor score from localization ( M5 ) to extension ( M2 ) is an emergency even if someone is still quoting "GCS around 7."
FOUR score when the voice is a ventilator
The Full Outline of UnResponsiveness (FOUR) score assigns 0–4 points each to eye response , motor response , brainstem reflexes , and respiration . The total ranges from 0 to 16 . Because there is no verbal item, an intubated patient can still receive a complete score. That is the practical reason FOUR appears in neuro-ICU stems: GCS loses its verbal column the moment the tube goes in, while FOUR still grades whether pupils and corneals are present and whether the patient over-breathes the ventilator or is apneic on it.
- FOUR domain (0–4) What a high score looks like What a 0 looks like
- Eye Open, tracking, or blinking to command Remain closed to pain
- Motor Thumbs-up, fist, or peace sign to command No response, or generalized myoclonus status
- Brainstem Pupil and corneal reflexes present Absent pupils, corneal, and cough
- Respiration Not intubated, regular breathing Apnea, or breaths only at the set ventilator rate
A FOUR brainstem of 0 plus respiration of 0 is the picture of a lost brainstem, but only after confounders are gone. This section does not replace the 2023 AAN/AAP/CNS/SCCM death-by-neurologic-criteria checklist taught later in this guide.
NIHSS is a stroke deficit scale
The National Institutes of Health Stroke Scale (NIHSS) scores 11 item groups from 0 to 42 . Zero is a normal screen; higher scores mean a larger, more disabling deficit. NIHSS is built for acute ischemic stroke : level of consciousness, gaze, visual fields, face, limbs, ataxia, sensory, language, dysarthria, and extinction or inattention. It is the wrong tool for a purely comatose subarachnoid-hemorrhage patient with no focal cortical signs, and it is not a herniation scale. If a stem gives NIHSS 22 with forced gaze and hemiplegia, think a large-vessel syndrome. If it gives GCS 4 with a blown pupil, think herniation physiology.
Pupils, extraocular reflexes, and lower cranial nerves
Record size in millimeters , shape , and light reactivity on each side, and say whether you used a bright flashlight in a dim room. Anisocoria of about 1 mm can be physiologic. A unilateral dilated, poorly reactive or fixed pupil in a patient with a supratentorial mass is uncal herniation until you prove otherwise: the medial temporal uncus crowds the tentorial notch and compresses the ipsilateral oculomotor nerve (CN III) . Contralateral hemiparesis is typical. Kernohan's notch is the false-localizing exception: the opposite cerebral peduncle is jammed against the tentorium, so hemiparesis appears ipsilateral to the blown pupil.
Bilateral pinpoint pupils suggest opioid effect or pontine injury. Bilateral midposition fixed pupils suggest midbrain damage. A sluggish pupil after recent intraocular surgery, or a glass eye, is not herniation.
Corneal reflex: afferent trigeminal (CN V) , efferent facial (CN VII) . Touch the cornea, not the sclera, and watch for a blink. Absence with an intact facial nerve points to an afferent or midbrain–pontine pathway failure.
Oculocephalic (doll's-eye) testing is allowed only after the cervical spine is cleared. In a comatose patient with an intact pons, the eyes move conjugately opposite the head turn. An awake person suppresses this. Cold calorics (vestibulo-ocular reflex) use ice water in an intact external canal: slow tonic deviation toward the cold ear if the brainstem is intact. A fast-phase nystagmus requires cortex that can generate that phase, so in coma you are looking for the slow tonic movement, not a carnival-wheel nystagmus.
Gag (CN IX/X) and cough (mainly CN X, plus carinal afferents) test the medulla. A strong cough on tracheal suction in an intubated patient is a medullary sign you will never see on GCS.
Motor findings: brain versus spinal cord
A cortical or capsular lesion produces contralateral face and arm weakness, often with the leg as well, in an upper-motor pattern once spinal shock fades. Decorticate posturing (abnormal flexion of the arms) implicates diencephalic or hemispheric pathways above the red nucleus. Decerebrate posturing (extension of arms and legs) implicates the midbrain and upper pons. Triple flexion of a leg to a nail-bed stimulus can be a spinal reflex and does not prove that the cortex felt pain.
A spinal level—thoracic sensory belt, flaccid areflexic legs, spared face, normal pupils—is not uncal herniation. Priapism, paradoxical breathing, and a clear sensory level push you toward cord injury. Do not call a spinal patient "GCS 6" because the legs do not move if the face obeys commands and the eyes track.
Herniation syndromes
Syndrome What shifts Earliest bedside clue Later catastrophe
Uncal Medial temporal lobe over the tentorial notch Ipsilateral fixed dilated pupil (CN III) Contralateral (or Kernohan ipsilateral) hemiparesis, coma, Duret hemorrhages
Central (transtentorial) Diencephalon then brainstem downward Bilateral small reactive pupils, Cheyne–Stokes, progressively less arousable Midposition fixed pupils, central neurogenic hyperventilation, then ataxic breathing and flaccid tone
Tonsillar Cerebellar tonsils through the foramen magnum Occipital headache, neck stiffness, downbeat nystagmus Sudden apnea and cardiovascular collapse from medullary compression
Subfalcine (cingulate) Cingulate gyrus under the falx Contralateral leg-predominant weakness from ACA compression ACA infarct, then progression into central herniation
Upward Cerebellum up through the tentorial notch After a posterior-fossa mass or over-drainage of a ventricular catheter Midbrain compression, bilateral midposition pupils
Cushing physiology—hypertension, bradycardia, and irregular breathing—appears late , when ischemia reaches the medulla. Do not wait for a full Cushing triad to treat a newly blown pupil.
Confounders that invalidate the exam
Before you believe "no brainstem reflexes," subtract the following:
Sedation and analgesia (propofol, midazolam, opioids, barbiturates, ketamine): wait for metabolism or reverse what is reversible.
Hypothermia : a cold brain is hyporeflexic. A patient at 32 °C is not a death-by-neurologic-criteria examination.
Neuromuscular blockade : a train-of-four of 0/4 means motor, an orbicularis-dependent corneal, and breathing effort cannot be interpreted. Check a twitch monitor.
Metabolic and toxic : profound hypoglycemia, hypercarbia, hyponatremia, hepatic or uremic encephalopathy, and recent high-dose CNS depressants.
If the stem says the patient received vecuronium an hour ago and "has no cough," the next step is to confirm recovery from paralysis, not to declare brainstem failure. Independent practice items at /practice/abim-neurocritical-care are a study bank for this reasoning, not the computer-based examination administered by ABPN.