FOUNDATIONS – Introduction & Neurological Examination

Neurology is primarily a clinical specialty. In most cases, accurate diagnosis depends more on history and examination than on investigations. The objective of neurological evaluation is to:

1. Identify whether the problem is neurological

2. Localize the lesion within the nervous system

3. Determine the nature of the pathology

4. Formulate a differential diagnosis

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Step 1: Is the Problem Neurological?

Symptoms suggesting neurological disease include:

• Weakness

• Sensory loss

• Abnormal movements

• Altered consciousness

• Speech or vision disturbances

• Gait abnormality

• Seizures

Many systemic illnesses (electrolyte disorders, hepatic or renal failure, infections) may mimic neurological disease, so this distinction is crucial.

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Step 2: Localization of Lesion

Localization is the hallmark of neurology.

Broad anatomical divisions:

• Cerebral cortex

• Subcortical structures

• Brainstem

• Cerebellum

• Spinal cord

• Peripheral nerves

• Neuromuscular junction

• Muscle

For example:

• Hemiparesis with aphasia → dominant cerebral hemisphere

• Quadriparesis with sensory level → cervical spinal cord

• Distal symmetric sensory loss → peripheral neuropathy

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Step 3: Temporal Profile

The time course gives strong clues to etiology:

Onset ----> Likely causes

Sudden- Stroke, seizure, trauma

Acute (hours–days)- Infection, inflammation

Subacute (days–weeks)- Demyelination, tumor

Chronic (months–years)- Degenerative, hereditary

 

Step 4: Nature of Pathology

Pathology may be:

• Vascular

• Infective

• Inflammatory

• Degenerative

• Neoplastic

• Metabolic or toxic

• Hereditary

General neurological examination provides systemic clues and should never be skipped.

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1. General Physical Examination

Pulse

• Bradycardia → raised intracranial pressure (Cushing reflex)

• Tachycardia → autonomic dysfunction

• Irregularly irregular pulse → atrial fibrillation (embolic stroke risk)

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Blood Pressure

• Hypertension → intracranial hemorrhage

• Orthostatic hypotension → autonomic dysfunction

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Temperature

• Fever suggests:

  • Meningitis

  • Encephalitis

  • Brain abscess

  • Epidural abscess

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2. General Inspection

Look for:

• Posture

• Involuntary movements

• Asymmetry

• Muscle wasting

• Gait abnormality

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3. Skin and Systemic Clues

• Pallor → B12 deficiency

• Icterus → hepatic encephalopathy

• Clubbing → syringomyelia

• Hyperpigmentation → Addison’s disease

• Neurocutaneous markers → phakomatoses

Higher mental functions reflect cortical integrity, especially frontal and temporal lobes.

1. Level of Consciousness

Consciousness has two components:

• Arousal (brainstem reticular activating system)

• Awareness (cerebral cortex)

 State                                                               Description                       

 -------------------                                           ---------------
Coma                                                              No arousal or awareness      

Stupor                                                            Arousable only to painful stimuli
Delirium                                                        Fluctuating attention, confusion  

Persistent vegetative state                Wakefulness without awareness     

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Glasgow Coma Scale (GCS)

Component: Score

Eye opening: 1–4

Verbal response: 1–5

Motor response: 1–6

GCS ≤ 8 = coma

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2. Orientation

Assess orientation to:

• Time

• Place

• Person

Disorientation to time occurs first, then place, then person.

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3. Attention

Attention is assessed by:

• Digit span (forward and backward)

• Serial sevens

• Months backward

Impaired attention is characteristic of delirium.

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4. Memory

Type-  Assessment

Immediate-  Digit span

Recent-  Recall after 5 minutes

Remote-  Past events

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Memory disorders:

• Anterograde amnesia → hippocampal lesions

• Retrograde amnesia → cortical involvement

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5. Intelligence and Calculation

• Serial subtraction

• Simple arithmetic

• Abstract thinking

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Speech and Language-

Speech is often confused with language, but they are distinct.

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Components of Speech

1. Phonation – sound production (larynx)

2. Articulation – movement of lips, tongue, palate

3. Resonance – nasopharyngeal closure

4. Prosody – rhythm and intonation

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Language

Language is a cortical function and includes:

• Comprehension

• Expression

• Naming

• Repetition

• Reading and writing

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Dysarthria

• Motor speech disorder

• Language intact

• Causes:

  • Bulbar palsy

  • Pseudobulbar palsy

  • Cerebellar disease

  • Parkinsonism

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Aphasia

• Language disorder

• Cortical lesion (dominant hemisphere)

Examples:

• Broca’s aphasia – nonfluent, good comprehension

• Wernicke’s aphasia – fluent, poor comprehension

Unconsciousness indicates bilateral hemispheric or brainstem dysfunction.

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Causes

• Structural: stroke, tumor, hemorrhage

• Metabolic: hypoglycemia, uremia, hepatic failure

• Infective: meningitis, encephalitis

• Toxic: drugs, alcohol

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Initial Assessment

1. Airway, breathing, circulation

2. GCS

3. Pupillary size and reaction

4. Motor response

5. Brainstem reflexes

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Pupillary Abnormalities

• Pinpoint pupils → pontine lesion

• Dilated fixed pupil → uncal herniation

• Unequal pupils → third nerve compression

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Motor Response

• Decorticate posture → hemispheric lesion

• Decerebrate posture → brainstem lesion

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Brainstem Reflexes

• Corneal reflex

• Oculocephalic reflex

• Gag reflex

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Approach Summary

A systematic approach helps distinguish:

• Structural vs metabolic coma

• Supratentorial vs infratentorial lesions