Neurologic Exam & Functional Neuroanatomy
Course Overview and Learning Objectives
Course Identification: PSYC 375 — Neurologic Exam as a Lesson on Neuroanatomy
Course Administration: Chapter quizzes are due at the start of the Unit 1 examination.
Learning Objectives:
Understand the fundamental components of a comprehensive neurologic exam.
Correlate specific neurological exam findings directly with functional neuroanatomy.
Recognize the critical diagnostic importance of the neurological exam in clinical decision-making.
Identify key clinical findings from each exam subdivision.
Adapt examination procedures for special clinical situations (e.g., comatose or uncooperative patients).
Review common clinical examples of neurological deficits and syndromes.
Purpose and Clinical Value of the Neurologic Exam
Clinical Significance:
Acts as a critical way station in clinical decision-making.
Rapidly answers urgent clinical questions (such as differentiating acute stroke from cardiac conditions).
Evaluates functional capacity and titrates a patient's precise level of functional impairment.
Enables accurate clinical diagnosis and guides effective treatment interventions.
Pinpoints and localizes lesions within the central and peripheral nervous systems.
The Six Main Subdivisions of the Neurologic Exam
1. Mental Status
2. Cranial Nerves
3. Motor Exam
4. Reflexes
5. Coordination and Gait
6. Sensory Exam
Mental Status Examination
Assessment Domains and Test Methods:
Attention: Tested by asking the patient to spell a word forward and backward (e.g., spelling "WORLD").
Orientation: Assessed by evaluating the patient's knowledge of their name, current physical location, and current date.
Memory:
Recent Memory: Evaluated via list learning or story recall tasks.
Remote Memory: Evaluated by asking about verifiable past personal or historical events.
Language: Assesses auditory comprehension, object naming, phrase repetition, reading, and writing.
Calculations: Tested using simple mathematical problems and left/right discrimination tasks.
Apraxia: Assessed by asking the patient to perform complex, learned, multi-step motor tasks on command (e.g., demonstrating how to brush teeth).
Neglect and Constructions:
Neglect: Evaluates awareness of and attention to the surrounding spatial environment.
Constructions: Tested through constructional tasks such as drawing a clock face set to a specific time.
Sequencing and Frontal Release Signs: Tested using repeated motor hand action sequences (e.g., fist, open palm, side of hand sequence).
Logic and Abstraction: Assessed by asking the patient to solve simple conceptual problems or explain proverbs.
Delusions and Hallucinations: Evaluated through direct clinical questioning regarding false fixed beliefs (delusions) or ungrounded sensory perceptions (hallucinations).
Mood: Evaluated via clinical observation and inquiry for signs of depression or mania.
Cranial Nerves Assessment
Cranial Nerve Functions (Pairs through ):
$ ext{CN I}$ (Olfactory): Olfaction (smell).
$ ext{CN II}$ (Optic): Vision.
$ ext{CN III}$ (Oculomotor): Extraocular eye movement, pupillary constriction, and near vision accommodation.
$ ext{CN IV}$ (Trochlear): Eye movement (downward depression and inward rotation).
$ ext{CN V}$ (Trigeminal): Facial sensation and motor control of mastication muscles.
$ ext{CN VI}$ (Abducens): Outward (lateral) eye movement.
$ ext{CN VII}$ (Facial): Facial expressions, taste (anterior two-thirds of tongue), lacrimation, and salivation.
$ ext{CN VIII}$ (Vestibulocochlear): Hearing and balance.
$ ext{CN IX}$ (Glossopharyngeal): Swallowing, taste (posterior third of tongue), and pharyngeal sensation.
$ ext{CN X}$ (Vagus): Swallowing, vocal cord/voice regulation, and visceral parasympathetic innervation.
$ ext{CN XI}$ (Spinal Accessory): Neck turning and shoulder elevation muscle movement.
$ ext{CN XII}$ (Hypoglossal): Tongue muscle movement.
Clinical Cranial Nerve Tests:
Blink-to-Threat: Assesses visual pathways and reflexive eye closure.
Pupillary Responses: Evaluates direct and consensual light responses ($ ext{CN II}$ and $ ext{CN III}$).
Extraocular Movements and Vestibulo-Ocular Reflex (VOR):
Oculocephalic Maneuver (Doll's Eyes Test): Evaluates fixed eye position during passive head rotation.
Caloric Stimulation:
Cold water instillation in one ear causes slow movement toward that ear with fast corrective saccades away (eyes move away).
Warm water instillation in one ear causes slow movement away with fast corrective saccades toward that ear (eyes move in the same direction).
Corneal Reflex, Facial Asymmetry, and Grimace Response: Assesses sensory input ($ ext{CN V}$) and motor facial response ($ ext{CN VII}$).
Gag Reflex: Stimulates posterior pharyngeal wall to test afferent ($ ext{CN IX}$) and efferent ($ ext{CN X}$) loops.
Motor Examination
Assessment Components:
Observation: Screening for involuntary movements, tremors, and overall speed of motor execution.
Inspection: Examining muscle groups for localized atrophy (wasting) or fasciculations (twitching).
Palpation: Checking muscle bellies for tenderness or subcutaneous twitching.
Muscle Tone: Evaluating passive resistance to movement across joint ranges.
Functional Testing: Performing rapid fine motor tasks such as fine finger movements and rapid toe tapping.
Strength Testing: Rating individual muscle group resistance against force.
Reflexes Evaluation
Plantar Response Differentiation:
Normal Plantar Reflex: Plantarflexion (downward flexing) of the toes when the lateral sole of the foot is stroked in healthy adults.
Babinski Reflex/Sign: Abnormal extension (dorsiflexion) of the hallux with spreading of the other toes upon plantar stimulation in adults, signaling upper motor neuron dysfunction (though normal in infants).
Special Reflex Testing: Elicited during specialized clinical scenarios (such as suspected central nervous system damage).
Coordination and Gait
Coordination Testing:
Appendicular Coordination Tests: Finger-nose-finger test and heel-to-shin test.
Ataxia: A disorder of muscle coordination characterized by poor muscle control leading to clumsy, uncoordinated voluntary movements.
Gait Assessment:
Tandem Gait: Walking in a straight line placing heel directly to toe.
Gait Apraxia: Inability to coordinate leg movements for walking while in an upright standing position, despite demonstrating normal leg motor mechanics when recumbent (lying down).
Differential Diagnosis: Ataxia vs. Apraxia:
Ataxia:
Physical inability to coordinate motor movement.
The patient comprehends the instruction and intends to perform the act, but execution is physically jerky and clumsy.
Example: Inability to smoothly touch finger to nose.
Apraxia:
Loss of the capability to program learned, purposeful motor plans.
The patient understands the command and has intact baseline strength and physical coordination, but cannot translate the conceptual task into the correct sequence of motor actions.
Example: Inability to perform the motion to "wave goodbye" on command.
Sensory Testing
Graphesthesia: The ability to identify letters or numbers traced onto the skin. Impairment suggests parietal lobe lesions.
Extinction: An abnormal cortical sensory phenomenon seen in acquired brain injury where a patient detects a touch stimulus on either side when presented individually, but fails to perceive the stimulus on the affected side when both sides are touched simultaneously (double simultaneous stimulation).
Confounding Factors in the Neurologic Exam
Cross-Domain Impairments: Deficits in one domain frequently distort testing accuracy in another domain.
Testing Prerequisites:
Patient alertness / consciousness level
Intact language comprehension
Willingness and ability to cooperate
Absence of severe primary sensory or motor neglect
Non-Organic Disorders Mimicking Neurologic Deficits
Conversion Disorder: Emotional or psychological stressors manifest as genuine sensory or motor deficits without an underlying focal neurological lesion.
Somatization Disorder: Presence of multiple chronic, physical symptom complaints that shift location and character over time.
Factitious Disorder: Conscious fabrication or self-induction of medical symptoms for primary internal gain (e.g., emotional comfort or medical attention).
Malingering: Intentional production or exaggeration of physical deficits for secondary external gain (e.g., financial compensation, avoiding work, or legal protection).
The Coma Examination Protocol
Assessment Approach:
Unconscious patients cannot perform cooperative clinical commands (e.g., object naming, line walking, following multi-step commands).
Assessment relies heavily on brainstem reflexes.
Goal is to titrate the depth of impairment and precisely grade the level of consciousness.
Continuum of Consciousness:
Ranges continuously from completely unresponsive with closed eyes to fully awake.
Neurological Etiologies of Impaired Consciousness:
Damage to the ascending reticular activating system (reticular formation) or bilateral structural lesions of the thalami or cerebral hemispheres.
Unilateral cortical or thalamic lesions (typically produce milder alterations).
Toxic or metabolic disturbances diffusely affecting the reticular formation, thalami, or cerebral cortex.
Sensory and Motor Evaluation in Coma:
Observe for spontaneous motor movements.
Inspect resting muscle tone for left-to-right asymmetries.
Apply noxious/painful stimuli (starting with minimal stimulus force):
Observe for facial grimacing or physiological responses.
Determine whether motor responses represent purposeful, directed withdrawal away from the stimulus.
Neurological Conditions Mistaken for Coma
Akinetic Mutism:
Etiology: Severe damage to large areas of the frontal lobes or frontal lobe pathways.
Clinical Presentation: Extreme loss of motor/verbal initiative and minimal responsiveness.
Diagnostic Characteristics: Eyes remain open with preserved tracking or subtle facial expression changes in response to environmental stimuli, demonstrating underlying awareness.
Locked-in Syndrome:
Etiology: Structural lesion involving ventral brainstem motor pathways (e.g., basilar artery pontine infarction) or total peripheral neuromuscular blockade.
Clinical Presentation: Complete paralysis of voluntary body and facial movements with preserved intact sensation and normal consciousness.
Diagnostic Characteristics: Preserved vertical eye movements, saccades, and eye blinking. Sensory testing and communication are conducted using pre-established eye-blink codes.
Evaluation of Pseudocoma (Non-Coma State)
Definition: Non-organic, psychologically based unresponsiveness occurring without structural or metabolic brain damage.
Diagnostic Testing Procedures:
Hand-Dropping Test: The patient's hand is held directly above their face and released. In pseudocoma, the hand flinches or falls to the side to avoid striking the face.
Saccadic Eye Movements: Observation of visual fixation reveals fast refixation saccades, which are absent in true organic coma.
Caloric Testing: Cold/warm water irrigation produces intact fast-phase nystagmus, confirming intact cortical ocular drive.
Tools for Non-Organic Deficits:
Variable vs. Consistent Resistance: Strength testing reveals erratic, giving-way resistance rather than steady neurological weakness.
Hoover Test: Distinguishes true unilateral leg paresis from non-organic weakness. The examiner holds both calcanei while the patient attempts to lift the paretic leg; in organic weakness, involuntary downward pressure is felt under the contralateral calcaneus.
Unconscious Movement: Observing normal fluid limb movements when the patient believes they are not being evaluated or during sleep cycles.
Practice Review Questions
Question 1: A patient presents with normal primary motor movement. However, when instructed to imitate the actions of brushing their teeth, their motor execution is inaccurate. This clinical finding is an example of:
A. Aphasia
B. Agraphia
C. Gait dysfunction
D. Apraxia
Answer: D. Apraxia
Question 2: Mel has sustained brain damage and demonstrates severe lack of motor responsiveness; however, subtle facial expression shifts are occasionally noted during ambient conversation. The clinician should evaluate for:
A. A "locked-in" state (locked-in syndrome)
B. A state of altered consciousness/dreamlike state
C. Akinetic mutism
Answer: C. Akinetic mutism