CENTRAL NERVOUS SYSTEM EXAMINATION

I. HISTORY TAKING POINTS

1. Chief Complaints Analysis

When patient reports:

a) Weakness

Character: Flaccid, spastic, fatigable, episodic
- Flaccid → LMN lesion, Peripheral neuropathy, Guillain-Barré syndrome
- Spastic → UMN lesion (Stroke, MS, Myelopathy)
- Fatigable → Myasthenia Gravis
- Episodic → Periodic paralysis, Multiple sclerosis
Site:
- Hemibody → Stroke, Cortical lesion
- Quadriparesis → High cervical cord lesion, Brainstem
- Distal weakness → Peripheral neuropathy, Motor neuron disease
- Proximal weakness → Myopathy, Muscular dystrophy
Severity:
- Rapid progression → Stroke, GBS
- Slowly progressive → MND, Muscular dystrophy
- Relapsing-remitting → Multiple sclerosis

b) Sensory disturbances

Character: Numbness, tingling, burning, shooting pain
- Burning → Peripheral neuropathy (diabetes)
- Shooting → Root compression, Sciatica
- Loss of vibration/proprioception → Posterior column involvement
Site:
- Glove & stocking → Peripheral neuropathy
- Dermatomal → Nerve root lesion
- Hemisensory → Thalamic stroke
- Sensory level → Spinal cord lesion
Severity/Progression:
- Sudden onset → Infarct
- Gradual → Tumor, Degeneration

c) Headache

Character: Throbbing, dull, lancinating, band-like
- Throbbing → Migraine
- Dull, continuous → Tension headache, Tumor
- Early morning with vomiting → Raised ICP
Site:
- Unilateral → Migraine, Cluster
- Occipital → Cervical spondylosis, Posterior fossa tumor
Severity:
- Explosive onset → Subarachnoid hemorrhage
- Progressive → Tumor

d) Seizures

Character: Focal, Generalized, Myoclonic, Absence
- Focal → Structural lesion
- Generalized → Idiopathic epilepsy, metabolic
- Myoclonic → Juvenile myoclonic epilepsy
- Absence → Childhood absence epilepsy
Associated features: Aura, post-ictal confusion (Focal onset), tongue bite, incontinence

e) Gait disturbances

Type:
- Hemiplegic gait → UMN lesion
- Spastic gait → Paraplegia, Cord lesion
- Ataxic gait → Cerebellar lesion
- Festinant gait → Parkinsonism
- High-stepping → Peripheral neuropathy

f) Visual disturbances

Character: Blurring, diplopia, field defects, transient vision loss
- Blurring → Optic neuritis
- Diplopia → Brainstem lesion, CN palsy
- Field defects → Optic chiasm lesion (Bitemporal hemianopia)

g) Speech disturbances

Aphasia → Cortical (dominant hemisphere)
Dysarthria → Brainstem, CN lesion
Nasal voice → Palatal paralysis

h) Cognitive or Behavioral changes

Acute confusion → Encephalopathy
Chronic decline → Dementia, Frontal lobe lesion
Personality change → Frontal lobe tumor, Pick's disease

i) Vertigo

Peripheral: Severe, positional, with hearing loss (Labyrinthitis)
Central: Mild, persistent, with ataxia (Cerebellar stroke)

j) Autonomic dysfunction

Orthostatic hypotension → Autonomic neuropathy
Bladder dysfunction → Spinal cord involvement

2. Past History

Stroke, HTN, DM → Vascular causes
Trauma → Epidural/subdural hematoma
TB, HIV → Meningitis, Tuberculoma
Cancer → Paraneoplastic syndrome, brain metastasis

3. Family History

Huntington’s, Parkinson’s, Ataxia → Genetic predisposition
Epilepsy → Genetic or structural predisposition

4. Personal History

Alcohol → Cerebellar degeneration, Wernicke’s encephalopathy
Smoking → Vascular risk, Stroke

5. Occupational/Environmental History

Heavy metals → Encephalopathy
Rural residence → Neurocysticercosis

II. CLINICAL EXAMINATION POINTS (with diagnostic interpretation)

1. General Examination

Neurocutaneous markers:
- Café-au-lait spots → Neurofibromatosis
- Ash leaf macules → Tuberous sclerosis
Involuntary movements at rest → Parkinsonism, Chorea

2. Higher Mental Function Examination

Consciousness level

Drowsy, Comatose → Diffuse brain dysfunction (Trauma, Metabolic, Meningitis)

Orientation

Disorientation → Delirium, Dementia

Memory disturbance

Immediate → Attention deficit
Recent → Hippocampal lesion
Remote → Diffuse cortical dysfunction

Language

Fluent aphasia → Wernicke’s area lesion
Non-fluent → Broca’s area lesion
Global aphasia → Large MCA infarct

Apraxia, Agnosia

Apraxia → Dominant parietal lesion
Agnosia → Occipital/parietal lobe

Frontal lobe dysfunction

Disinhibition, impaired judgment

3. Cranial Nerve Examination

II - Optic nerve

Visual field defects:
- Bitemporal hemianopia → Pituitary tumor
- Homonymous hemianopia → Contralateral occipital/parietal lesion

III, IV, VI

Diplopia, ptosis → Brainstem lesion, raised ICP

Facial numbness → Trigeminal neuralgia, pontine lesion

VII

UMN palsy → Forehead sparing
LMN palsy → Bell’s palsy

VIII

Sensorineural deafness → Acoustic neuroma
Nystagmus → Vestibular dysfunction

IX, X

Nasal voice, dysphagia → Brainstem lesion

Shoulder droop → Accessory nerve lesion

XII

Tongue deviation → Ipsilateral LMN lesion, Contralateral UMN lesion

4. Motor System Examination

Bulk

Wasting → LMN lesion
Hypertrophy → Pseudohypertrophy in Duchenne

Tone

Spasticity → UMN lesion
Rigidity → Parkinsonism
Hypotonia → LMN, Cerebellar lesion

Power

Hemiparesis → Stroke
Distal weakness → Neuropathy
Proximal weakness → Myopathy

Involuntary movements

Tremor:
- Rest → Parkinsonism
- Intention → Cerebellar
- Postural → Essential tremor

Reflexes

Exaggerated → UMN lesion
Absent → LMN lesion
Plantar upgoing → Pyramidal tract lesion

Coordination

Dysmetria, intention tremor → Cerebellar
Dysdiadochokinesia → Cerebellar

Cranial Nerve Examination – Detailed

I – Olfactory Nerve

Tests:

Ask patient to close eyes & occlude one nostril. Present a non-irritant odor (coffee, vanilla, peppermint)
Ask to identify the smell. Repeat on both sides.

Interpretation:

Anosmia (loss of smell) → Trauma (cribriform plate fracture), Meningioma, Frontal lobe tumor
Parosmia (distorted smell) → Temporal lobe epilepsy
Hyposmia → Viral infection, aging
Hallucinations of smell → Uncinate fits

II – Optic Nerve

Tests:

A. Visual Acuity

Snellen’s chart (Distance)
Jaeger’s chart (Near vision)

B. Color Vision

Ishihara plates

C. Visual Fields

Confrontation test
Perimetry (Goldmann / Automated Humphrey)

D. Pupillary Reflexes

Direct light reflex
Consensual light reflex
Swinging flashlight test (Relative afferent pupillary defect)

E. Fundoscopy

Optic disc, Cup-disc ratio, Pallor, Papilledema, Retinal hemorrhages

F. Red Desaturation Test

Tests early optic neuritis

Interpretation:

Visual acuity ↓ → Optic neuropathy, Refractive errors
Field defects:
- Bitemporal hemianopia → Pituitary tumor
- Homonymous hemianopia → Optic tract lesion
- Central scotoma → Optic neuritis
Pupillary reflex abnormal → Optic nerve lesion

III, IV, VI – Oculomotor, Trochlear, Abducens Nerves

These are tested together

Tests:

A. Inspection

Ptosis → CN III palsy, Myasthenia

B. Eye Position

Strabismus, gaze deviation

C. Extraocular Movements (EOM)

Ask patient to follow finger in ‘H’ pattern

D. Diplopia Charting

Red-green glasses test
Hess chart

E. Convergence Test

F. Nystagmus observation

G. Pupil Size and Reactivity

Interpretation:

CN III palsy → Ptosis, ‘Down and out’ eye, Dilated pupil
CN IV palsy → Vertical diplopia, Head tilt
CN VI palsy → Medial deviation, inability to abduct

V – Trigeminal Nerve

Tests:

A. Sensory (V1, V2, V3 branches)

Light touch, pain, temperature over:
- Ophthalmic
- Maxillary
- Mandibular areas

B. Corneal Reflex

Afferent: V1
Efferent: VII

C. Motor

Palpate masseter & temporalis while clenching teeth

D. Jaw jerk reflex

Exaggerated in UMN lesion

Interpretation:

Loss of sensation in one branch → Peripheral nerve lesion
Loss in all divisions → Brainstem lesion, pontine infarct
Absent corneal reflex → CN V or VII lesion
Weak muscles of mastication → LMN lesion (pons)

VII – Facial Nerve

Tests:

A. Inspection

Facial asymmetry, forehead wrinkles, nasolabial fold

B. Motor Tests

Ask patient to:
- Raise eyebrows
- Close eyes tightly
- Show teeth
- Puff cheeks
- Whistle

C. Taste

Anterior 2/3rd of tongue: Sweet, salty

D. Stapedius reflex

Hyperacusis if impaired

E. Lacrimation test

Interpretation:

LMN lesion → Whole face affected (Bell's palsy)
UMN lesion → Forehead spared
Loss of taste → Chorda tympani lesion
Hyperacusis → Stapedius muscle involvement

VIII – Vestibulocochlear Nerve

Tests:

A. Cochlear Component

Finger rub test
Rinne’s test: AC > BC (normal)
Weber’s test: Lateralization in conductive loss
Audiometry (Pure tone)
Otoacoustic emissions

B. Vestibular Component

Dix-Hallpike maneuver → BPPV
Head impulse test → Vestibular hypofunction
Romberg’s test
Caloric test (COWS – Cold Opposite, Warm Same)

Interpretation:

Sensorineural loss → Acoustic neuroma, Labyrinthitis
Vertigo with nystagmus → Vestibular neuronitis, Cerebellar stroke

IX & X – Glossopharyngeal & Vagus Nerves

Tests:

A. Palatal Movement

Ask patient to say “Ah”
Observe uvula deviation

B. Gag Reflex

Afferent: IX
Efferent: X

C. Phonation

Hoarseness, nasal voice

D. Swallowing

E. Cough reflex

Interpretation:

Absent gag reflex → IX or X nerve lesion
Uvula deviated away from lesion → Unilateral vagus lesion
Nasal regurgitation → Palatal palsy

XI – Spinal Accessory Nerve

Tests:

A. Sternocleidomastoid strength

Ask patient to turn head against resistance

B. Trapezius strength

Shrug shoulders against resistance

Interpretation:

Weakness → LMN lesion in posterior triangle (surgical injury) or brainstem lesion

XII – Hypoglossal Nerve

Tests:

A. Tongue Inspection

Atrophy, fasciculations

B. Tongue Protrusion

Deviation → Towards side of LMN lesion

C. Tongue movement

Lateral movement, speed

Interpretation:

Deviation towards side of lesion → LMN palsy
UMN lesion → Contralateral weakness without atrophy

5. Sensory System Examination

Primary sensations

Loss of vibration/proprioception → Posterior column disease
Loss of pain/temp → Spinothalamic tract lesion
Sensory level → Spinal cord compression

Cortical sensations

Astereognosis → Parietal cortex lesion

6. Cerebellar Examination

Nystagmus, Dysarthria, Ataxia → Cerebellar lesion
Romberg positive → Sensory ataxia

7. Gait Examination

Spastic → UMN lesion
Ataxic → Cerebellar lesion
High stepping → Peripheral neuropathy
Parkinsonian → Basal ganglia disease

8. Meningeal Signs

Neck stiffness, Kernig’s, Brudzinski’s → Meningitis, SAH

9. Autonomic Nervous System

Orthostatic hypotension → Autonomic failure
Bladder dysfunction → Spinal cord lesion

10. Psychiatric Evaluation

Apathy, Disinhibition → Frontal lobe
Delirium → Acute diffuse dysfunction
Dementia → Alzheimer’s, Vascular, Lewy body

Friday, March 28, 2025