What should be included in a comprehensive Central Nervous System (CNS) systemic examination protocol?

Comprehensive Central Nervous System (CNS) Examination Protocol

A complete CNS examination protocol should include assessment of mental status, cranial nerves, motor system, sensory system, reflexes, and cerebellar function, with standardized documentation of findings to detect neurological abnormalities and monitor changes over time.

Mental Status Examination

• Level of Consciousness:

  • Assess alertness, orientation to person, place, time
  • Use standardized scales: Glasgow Coma Scale (GCS) or Full Outline of UnResponsiveness (FOUR) score 1
  • Document specific responses to verbal and tactile stimulation

• Cognitive Function:

  • Montreal Cognitive Assessment (MoCA) for comprehensive screening 1
  • Assess attention, memory, language, executive function
  • Test for frontal lobe signs (e.g., perseveration, utilization behavior)

Cranial Nerve Examination

1. CN I (Olfactory): Test smell identification in each nostril
2. CN II (Optic):
   • Visual acuity
   • Visual fields by confrontation
   • Fundoscopic examination
   • Pupillary light reflex
3. CN III, IV, VI (Oculomotor, Trochlear, Abducens):
   • Pupil size, shape, and reactivity
   • Eye movements in all directions (H-test)
   • Convergence
   • Nystagmus assessment 2
4. CN V (Trigeminal):
   • Facial sensation in all three divisions
   • Corneal reflex
   • Jaw strength and movement
5. CN VII (Facial):
   • Facial symmetry at rest and with movement
   • Test forehead, eye closure, smile, grimace
6. CN VIII (Vestibulocochlear):
   • Hearing assessment (whisper test or finger rub)
   • Weber and Rinne tests if indicated
7. CN IX, X (Glossopharyngeal, Vagus):
   • Palate elevation
   • Gag reflex
   • Voice quality and swallowing
8. CN XI (Spinal Accessory):
   • Shoulder shrug strength
   • Sternocleidomastoid muscle strength
9. CN XII (Hypoglossal):
   • Tongue protrusion and movement
   • Check for atrophy or fasciculations

Motor System Examination

• Inspection:

  • Muscle bulk
  • Fasciculations
  • Abnormal movements (tremor, chorea, dystonia) 1

• Tone:

  • Assess for rigidity, spasticity, or hypotonia
  • Test for cogwheel rigidity or lead-pipe rigidity

• Strength:

  • Grade using Medical Research Council (MRC) scale (0-5)
  • Test major muscle groups bilaterally
  • Document proximal and distal strength

• Coordination:

  • Finger-to-nose test
  • Heel-to-shin test
  • Rapid alternating movements 2

Sensory System Examination

• Light Touch: Test with cotton wisp in all dermatomes
• Pain: Test with pinprick in all dermatomes
• Temperature: If indicated
• Vibration: Test with 128 Hz tuning fork on bony prominences
• Proprioception: Test joint position sense in fingers and toes
• Cortical Sensory Function:
  • Two-point discrimination
  • Stereognosis (object recognition)
  • Graphesthesia (number recognition)

Reflex Examination

• Deep Tendon Reflexes:

  • Grade using 0-4+ scale
  • Test biceps, triceps, brachioradialis, patellar, and Achilles reflexes 2

• Pathological Reflexes:

  • Babinski sign
  • Hoffman sign
  • Grasp reflex
  • Snout reflex
  • Glabellar tap

Cerebellar Function

• Gait and Station:

  • Observe normal gait
  • Tandem gait (heel-to-toe walking)
  • Romberg test
  • Document gait pattern and classify if abnormal 2

• Coordination:

  • Finger-to-nose test
  • Heel-to-shin test
  • Dysdiadochokinesia (rapid alternating movements)
  • Intention tremor assessment 2

• Speech: Assess for scanning dysarthria 2

Additional Assessments

• Meningeal Signs:

  • Nuchal rigidity
  • Kernig's sign
  • Brudzinski's sign 1

• Autonomic Function:

  • Vital signs including orthostatic measurements
  • Pupillary responses
  • Sweating patterns

Documentation Requirements

• Document time of examination
• Record all positive and pertinent negative findings
• Use consistent terminology and grading scales
• Compare with previous examinations to identify changes 3

Special Considerations

• Altered Mental Status: Focus on pupillary response, motor response to pain, brainstem reflexes, and respiratory pattern 1
• Suspected Stroke: Include NIH Stroke Scale assessment
• Suspected Spinal Cord Injury: Document sensory and motor levels
• Suspected Increased Intracranial Pressure: Monitor for pupillary changes, decreased consciousness, Cushing's triad 4

Supplementary Diagnostic Tests

• Imaging:

  • MRI brain without contrast is gold standard for most evaluations 2
  • MRI with contrast when neoplasm, infection, or inflammation suspected
  • CT head for emergency settings or when MRI contraindicated 2

• Laboratory Tests (as indicated):

  • Basic metabolic panel
  • Thyroid function tests
  • Vitamin levels (B12, folate)
  • Inflammatory markers
  • Cerebrospinal fluid analysis 1

This comprehensive protocol ensures systematic evaluation of all CNS components, allowing for accurate detection of neurological abnormalities and monitoring of changes over time. Consistent application of this protocol will improve diagnostic accuracy and guide appropriate management decisions.