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L3 Nervous System Clinical Demonstration Neurological examination and assessment of brain function

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tagsnervoussystem, lecture
aliasesL3 Nervous System Clinical Demonstration Neurological examination and assessment of brain function

13 min read

Overview

A clinical demonstration covering the structure of the full neurological examination and the bedside tools used to assess brain function. The examination runs through seven components in order: mental status, cranial nerves, motor system, sensation, reflexes, stance and gait, and a final “other” group. Alongside the examination itself the lecture supplies a neurological system review (the symptom checklist for history-taking) and two formal cognitive instruments reproduced as handouts: the Frontal Assessment Battery (FAB), used to separate frontal dysexecutive dementias from Alzheimer’s type, and the Mini-Addenbrooke’s Cognitive Examination (M-ACE) scoring form.

The seven components of the neurological examination

The examination is structured as:

  1. Mental status - level of consciousness/orientation, general appearance and behaviour, cooperation, thought processes, mood, speech, intellectual functions.
  2. Cranial nerves - I to XII.
  3. Motor system - inspection, tone, strength, coordination.
  4. Sensation - touch, pain, temperature, vibration sense, position sense, cortical sensation.
  5. Reflexes - deep tendon, superficial, primitive.
  6. Stance and gait - heel-toe walking, Romberg’s test.
  7. Other - skull, spine, neck stiffness, sphincters, carotid arteries.

Mental status

Assessed under: level of consciousness/orientation, general appearance and behaviour, cooperation, thought processes, mood, speech, and intellectual functions.

Intellectual functions tested: digit span, serial sevens, memory, general knowledge, reasoning, and spelling WORLD backwards.

Speech: the key question is whether the abnormality is a

  • dysarthria (impaired articulation)
  • dysphasia (impaired language)
  • dysphonia (impaired voice)

Mood, speech and intellectual functions should be observed during the history. Further testing is indicated only if there appears to be a deficit in any area.

The Mini-Mental Status Examination may be used for a quantitative assessment of mental state.

A useful dementia screen:

  • Glabellar tap
  • Suck reflex
  • Spell WORLD backwards
  • Recall 3 items with distraction

Cranial nerves and how each is tested

  • I (smell) - test each nostril separately; note whether they merely smell something or actually recognise it.
  • II - visual fields by confrontation with fingers with both eyes open, each eye separately if in doubt; visual acuity with Snellen’s chart or a near vision chart; fundi by ophthalmoscopy looking at the discs, background retina, vessels and macula.
  • III, IV, VI - pupils (observation, light and accommodation reflex), lids (any ptosis?), eye movements.
  • V - sensation in all three divisions (light touch, pin-prick, temperature); motor by testing jaw opening, closure and deviation; corneal reflex; jaw jerk.
  • VII - facial muscles by testing grimace, eye closure, forehead wrinkling and platysma; taste over the anterior 2/3 of the tongue, tested only if there is a lower motor neurone facial palsy.
  • VIII - hearing acuity using a watch tick, finger rub or whisper with the opposite ear blocked; Rinne test; Weber test.
  • IX, X - palatal movement, gag reflex, swallowing, voice.
  • XI - sternomastoids (neck flexion and rotation), trapezii (shoulder shrug).
  • XII - tongue appearance and protrusion.

Important

UMN lesions affect the lower part of the face; LMN lesions affect the whole face.

Interpreting the hearing tests

  • Rinne: AC > BC is normal, or indicates sensorineural deafness. BC > AC indicates conductive deafness.
  • Weber: localises toward the side of a conductive deafness; away from the side of a sensorineural deafness.

Motor system

Inspection - posture, wasting, fasciculations, involuntary movements.

Tone - passively move the joints with the patient relaxed, using both slow and fast movements. Decide whether tone is normal, decreased, or increased (spasticity or rigidity).

Strength - the patient assumes a position and the examiner tries to overcome it, using appropriate force. Tested at:

  • Upper limbs: finger abduction, flexion, extension; wrist flexion, extension; elbow flexion, extension; shoulder abduction, adduction.
  • Chest: observe respiratory movements.
  • Abdomen: sit up from lying.
  • Lower limbs: toe flexion, extension; ankle flexion, extension; knee flexion, extension; hip flexion, extension, adduction and abduction.

Coordination

  • Finger-nose test in the upper limbs
  • Rapid alternating movements (impairment is dysdiadochokinesis)
  • Heel-shin test in the lower limbs
  • Holmes rebound phenomenon

Sensation

ModalityMethod
TouchCotton wool or paint brush
PainOrdinary pin or safety pin; do not re-use, and never use a hypodermic needle
TemperatureCold tuning fork; tubes of hot and cold water if there is time
Vibration128 cps tuning fork, tested on bony prominences
Position senseHold the digit on each side when testing

For vibration and position sense it is usually sufficient to test the tips of the fingers and toes, moving proximally only if there is a deficit.

Cortical sensation - localisation, two point discrimination, extinction, graphaesthesia, stereognosis. Only test cortical sensation if a central lesion is suspected and crude light touch is intact in the area being tested.

Reflexes

  • Deep tendon: biceps, triceps, supinator, knee, ankle.
  • Superficial: abdominal, cremasteric, plantar.
  • Primitive: glabellar tap, grasp, palmar mental, sucking.

Stance and gait

Assess gait, walking on heels and toes, and heel-toe walking.

Romberg’s test: the patient closes the eyes while standing with the feet together.

Warning

The slide states Romberg’s test is “positive if increased unsteadiness with the eyes open.” This is as recorded on the slide and appears internally inconsistent with the test as described (eyes closed); no further explanation is given.

Other

Skull and spine, neck stiffness, sphincters, carotid arteries.

Neurological system review

The symptom checklist for history-taking:

  • Headache
  • Loss of consciousness, convulsions
  • Memory
  • Sleep
  • Speech
  • Vision
  • Hearing
  • Taste
  • Smell
  • Dizziness, balance
  • Sensory disturbance: pain, loss of sensation, paraesthesiae, dysaesthesiae
  • Motor disturbance: weakness, wasting, loss of coordination
  • Gait
  • Autonomic: bladder, bowel, sweating, sexual function

Frontal Assessment Battery (FAB)

Purpose: a brief bedside or clinic tool to help discriminate between dementias with a frontal dysexecutive phenotype and Dementia of Alzheimer’s Type (DAT). It has validity in distinguishing frontotemporal dementia from DAT in mildly demented patients (MMSE > 24). Total score is out of a maximum of 18, with higher scores indicating better performance.

Interpretation: a cut-off score of 12 has a sensitivity of 77% and a specificity of 87% in differentiating frontal dysexecutive type dementias from DAT.

The six items

1. Similarities (conceptualization) - “In what way are they alike?” for a banana and an orange; a table and a chair; a tulip, a rose and a daisy. On the first item only, in the event of total failure (“they are not alike”) or partial failure (“both have peel”), help the patient by saying “both a banana and an orange are fruit”, but credit 0 for the item; do not help on the two following items. Only category responses (fruits, furniture, flowers) count as correct. Score: three correct 3, two correct 2, one correct 1, none 0.

2. Lexical fluency (mental flexibility) - “Say as many words as you can beginning with the letter ‘S’, any words except surnames or proper nouns.” If no response in the first 5 seconds, prompt “for instance, snake”; if the patient pauses 10 seconds, prompt “any word beginning with the letter ‘S’”. Time allowed is 60 seconds. Word repetitions or variations (shoe, shoemaker), surnames and proper nouns do not count. Score: > 9 words 3, 6-9 words 2, 3-5 words 1, < 3 words 0.

3. Motor series, “Luria” test (programming) - “Look carefully at what I’m doing.” The examiner, seated in front of the patient, performs the “fist-edge-palm” series alone three times with the left hand, then asks the patient to do the same series with the right hand, first together with the examiner (three times) and then alone. Score: six correct consecutive series alone 3; at least three correct consecutive series alone 2; fails alone but performs three correct consecutive series with the examiner 1; cannot perform three correct consecutive series even with the examiner 0.

4. Conflicting instructions (sensitivity to interference) - “Tap twice when I tap once”, checked with a 1-1-1 trial series; then “Tap once when I tap twice”, checked with a 2-2-2 trial series. The examiner then performs 1-1-2-1-2-2-2-1-1-2. Score: no errors 3, 1-2 errors 2, > 2 errors 1, patient taps like the examiner at least four consecutive times 0.

5. Go-No Go (inhibitory control) - “Tap once when I tap once”, checked with a 1-1-1 trial series; then “Do not tap when I tap twice”, checked with a 2-2-2 trial series. The examiner then performs 1-1-2-1-2-2-2-1-1-2. Score: no errors 3, 1-2 errors 2, > 2 errors 1, patient taps like the examiner at least four consecutive times 0.

6. Prehension behaviour (environmental autonomy) - “Do not take my hands.” With the patient’s hands placed palm up on the knees, the examiner, seated in front and without speaking or looking at the patient, brings his own hands close and touches the palms of both the patient’s hands to see whether the patient spontaneously takes them. If the patient does, try again after saying “Now, do not take my hands.” Score: does not take the hands 3; hesitates and asks what to do 2; takes the hands without hesitation 1; takes the hands even after being told not to 0.

References: Dubois B, Litvan I. The FAB: a frontal assessment battery at bedside. Neurology 55(11):1621-1626, 2000. Slachevsky A, Dubois B. Frontal Assessment Battery and Differential Diagnosis of Frontotemporal Dementia and Alzheimer Disease. Archives of Neurology 61(7):1104-1107, 2004.

Mini-Addenbrooke’s Cognitive Examination (M-ACE)

A structured cognitive screening form (New Zealand Version A, 2020), reproduced as a two-page template. Total score is out of 30. The form records patient details including name, date of birth, gender, date and time of testing, address, NHI, tester’s name and designation, age at leaving full-time education, occupation and handedness.

Domains and scoring

  • Attention [0-4] - ask the day, date, month and year.
  • Memory (registration) [0-7] - “I’m going to give you a name and address and I’d like you to repeat the name and address after me. So you have a chance to learn, we’ll be doing that 3 times. I’ll ask you the name and address later.” Three trials are recorded but only the third trial is scored. The name and address is Harry Barnes / 73 Church Street / Woodville / Hawkes Bay.
  • Fluency, animals [0-7] - “Now can you name as many animals as possible. You have one minute. Go ahead.” Raw-to-scaled conversion: 22 = 7, 17-21 = 6, 14-16 = 5, 11-13 = 4, 9-10 = 3, 7-8 = 2, 5-6 = 1, < 5 = 0.
  • Visuo-spatial, clock drawing [0-5] - present the form to the person as is (i.e. upside down) and cover the name/address in the memory recall section so it cannot be seen. Ask the subject to draw a clock face with the hands at ten past five. Scoring: circle = 1, numbers = 2, hands = 2 if all correct.
  • Memory recall [0-7] - cover the address and ask “Now tell me what you remember about that name and address we were repeating at the beginning.”

Warning

The source form gives the memory address as “73 Church Street” on page 1 and “72 Church Street” on page 2. This discrepancy is present in the source material and is not resolved by the slides.

Self-test

  1. List the seven components of the neurological examination in order.
  2. Distinguish dysarthria, dysphasia and dysphonia.
  3. List the four elements of the useful dementia screen given in the lecture.
  4. A patient has a facial weakness sparing forehead wrinkling. Is this an upper or lower motor neurone lesion, and what is the rule you applied?
  5. In the same patient, would you go on to test taste over the anterior 2/3 of the tongue? Explain.
  6. Interpret a Rinne test showing BC > AC, and a Weber test that localises toward the tested ear.
  7. Describe how tone is examined and what abnormalities you are deciding between.
  8. List the four coordination tests described.
  9. What equipment is specified for testing vibration sense, and where is it applied?
  10. State the two conditions that must be met before you test cortical sensation, and name the five cortical sensory modalities.
  11. Name the three groups of reflexes tested and give the members of each.
  12. What is the maximum score on the FAB, and what does the cut-off of 12 achieve, with what sensitivity and specificity?
  13. Describe the Luria motor series item of the FAB, including how a score of 2 is earned.
  14. In the FAB conflicting instructions item, why does a patient who simply copies the examiner score 0 rather than being scored on error count?
  15. What is the maximum total score of the M-ACE, and what are its five scored sections with their maxima?
  16. A patient names 12 animals in one minute on the M-ACE. What fluency score do they receive?
  17. Explain why two of the FAB items (prehension behaviour, Go-No Go) and two of the primitive reflexes (grasp, sucking) probe overlapping territory, and what that territory is.

Answers

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