Neurologic Localization for M3s

Kevin Chan Teo Ting Wei

Edited from Dr Eugene Gan’s slides (Batch of 2016)

#1: Where is the lesion?

Where Upper/Lower

Symmetrical/Asymmetrical

Unilateral/Bilateral

Sensory Hallmarks

Cortex

Subcortical

Brainstem

Spinal Cord

Anterior Horn Cell

Plexus, Roots

Peripheralnerves

NMJ

Muscles

Where Upper/Lower

Symmetrical/Asymmetrical

Unilateral/Bilateral

Sensory Hallmarks

Cortex Upper Asymmetrical Unilateral +/- CrossedCortical Signs

Subcortical Upper Asymmetrical Unilateral +/- LacunarSyndromes

Brainstem Upper Asymmetrical Unilateral +/- Crossed Hemiparesis

Spinal Cord Upper Symmetrical Bilateral -(SS lvl)

Cord syndromes, ARU

Anterior Horn Cell

Mixed Symmetrical Bilateral/Unilateral

+ Fasciculations, CNs affected

Plexus, Roots

Lower Asymmetrical Unilateral - Dependent on levels affected

Peripheralnerves

Lower Symmetrical Bilateral +/- Length-dep distal weakness

NMJ Lower Symmetrical Bilateral + Prox weakness, fluctuating fatig

Muscles Lower Symmetrical Bilateral + Prox weakness,check CN

UMN lesion LMN lesion Mixed lesion

General Inspection(chronicity)

Minimal wasting, unless chronic

Wasting, contractures

Wasting, contractures,fasciculations

Tone +++ --- +/-

Reflexes +++ --- +/-

Plantars Up-going plantarsClonus

Down-going plantars +/-

Power UL: flexors > extensorsLL:extensors > flexors

Dependent on site of lesion

Globally reduced

#2: What is the etiology?

Differential Diagnoses(supporting risk factors)

• Sudden onset– Vascular (stroke)– Trauma– Epilepsy (Todd’s paralysis)

• Subacute onset– Infection (TB abscess, meningitis)– Inflammation (lupus, MS)

• Gradual onset– Degeneration (PD)– Demyelination (MS)– SOL (hydrocephalus, neoplasm)

• Variable onset– Metabolic (hypoglycemia great mimicker of neuro conditions)– Toxic/paraneoplastic

Now, back to basics

Reflexes

1. Afferent (Sensory)

2. Efferent (AHC + Peripheral nerve)

3. Modulation (UMN)

Examples of Reflex Arcs

Spinal-Biceps & Brachioradialis (C5-6)-Triceps (C7-8)-Hoffman’s (C8)-Cremasteric Reflex (L1)-Knee Jerk (L3-4)-Babinski, Ankle Jerk (S1)-Anal Sphinctor Tone (S2-S4)

Cranial-Pupilliary Light Reflex (CN II-III) -Corneal Reflex (CN V1 – VII)-Jaw Jerk Reflex (CN V3 – V3)-Gag Reflex (CN IX-X)

Teaching points about reflexes

1)An hyper-reflexic jerk (Nuclear) should prompt you to think upwards (Supra-nuclear)

2) A hypo-reflexic jerk should prompt you to think of

- Afferent

- Efferent

The neuro limbs exam1. Inspection 2. Tone

– Hyper– Normal– Hypo

3. Reflexes– Hyper– Normal– Hypo/Absent

4. Power– Proximal vs Distal vs Other patterns

5. Sensation– Pattern of loss (Glove and stocking vs Dermatomal vs Nerve Distribution)– Modalities lost

• Pain + Temperature• Fine Touch + Vibration

6. Cerebellar– Involved/uninvolved

Important features of weakness1. UMN vs LMN

– UMN: Spinal cord and above– LMN: AHC and below

2. Proximal vs Distal– Proximal: Myopathy, NMJ or MND– Distal: Wide range of differentials. MND and myotonia dystrophica may present with distal

weakness.

3. Unilateral vs Bilateral– Unilateral: Peripheral nerve/plexus compression, spinal cord, strokes– Bilateral: Myopathies, NMJ, MND, Cord syndromes, Cord transections

4. Sensory involvement– If sensory involved, unlikely to be myopathy/NMJ– Glove and stocking: Peripheral neuropathy, cervical myelopathy– Peripheral nerve distribution: nerve compression, mononeuropathy, mononeuritis multiplex– Dermatomal: Radiculopathy

5. Specific distinguishing features– Muscular pain/skin involvement points to myositis– Fatigability and ocular involvement suggests MG

6. Misc.– GBS can present with almost any pattern of LMN weakness, with or without sensory

involvement

Weakness

• Bilateral upper motor neuron weakness with sensory level at L2

– With a history of RTA?

– With signs of raised ICP?

– In an immunocompromised patient with fever?

– In a known cancer patient with back pain?

Weakness

• Weakness of left lower limb, power 5/5 on hip flexion and extension. Power 5/5 on knee flexion and extension. Power 3/5 on ankle dorsiflexion and 5/5 on plantarflexion. Knee jerk reflex 2+, ankle jerk 2+, plantar reflex downgoing. Sensory loss of pain and temperature to lateral aspect of leg and dorsum of foot

• Translation: Unilateral distal weakness with sensory loss• Upper limb examination normal• Likely levels

– Peripheral Nerve – Common peroneal nerve– Radiculopathy – L4-L5– Plexus?

• How to differentiate?– Hip Abduction

Weakness

• Weakness of both lower limbs, power 3/5 on hip flexion and extension. Power 3/5 on knee flexion and extension. Power 4+/5 on ankle dorsiflexion and plantarflexion. Knee jerk reflex 1+, ankle jerk 2+, plantar reflex downgoing. No sensory loss of pain/temperature or vibration/proprioception

• Translation: Bilateral proximal weakness with hyporeflexiaand no sensory loss (LMN proximal weakness, no sensory involvement)

• Similar upper limb pattern of weakness• Likely levels

– Muscle– NMJ

Weakness

• Bilateral proximal weakness with hyporeflexiaand no sensory loss (LMN proximal weakness, no sensory involvement)

– In a 15 year old boy with a family history?

– In a 40 year old woman with a rash?

– In a 65 year old man with diplopia and whose weakness is worse at night?

– In a 70 year old man taking statins with muscle pain?

Weakness

• Weakness of both lower limbs, power 5/5 on hip flexion and extension. Power 5/5 on knee flexion and extension. Power 4/5 on ankle dorsiflexion and plantarflexion. Power 3+/5 on big toe extension. Knee jerk reflex 1+, ankle jerk 1+, plantar reflex absent. Sensory loss of pain and temperature in dorsal and plantar aspects of the feet.

• Similar findings in the upper limb• Translation: Bilateral distal weakness with hyporeflexia and

sensory loss involving both upper and lower limbs (LMN distal weakness with sensory involvment)

• Likely level– Peripheral nerve (peripheral neuropathy)

Differentials for peripheral neuropathies

• Alcohol, AIDP

• B12

• CIDP, carcinoma

• Diabetes, drugs

• Familial (HMSN, CMT)

The neuro cranial nerves exam1. Smell

2. Pupils (CN 2 afferent, CN 3 efferent)

– Big/Small

– Reactive/Nonreactive

3. Visual Field (Somewhat cortical)

– Complete monocular blindness

– Bitemporal hemianopia

– Homonymous hemianopia (more vs less congruent)

– Homonymous hemianopia with macular sparing

4. EOMs (CN 3, 4 and 6)

– Simple vs Complex ophthalmoplegia

– Medical vs surgical third nerve

5. Sensation (CN V)

– Intact vs lost

6. Hearing (CN 8)

– Rinee and Webers

7. Motor (CN V3, 7, 10, 11, 12)

– CN 7 UMN vs LMN

4 Cranial Nerve Rules

1. All cranial nerves except CN 1 and 2 arise from the brainstem– 3, 4 from midbrain– 5, 6, 7, 8 from pons– 9, 10, 11, 12 from medulla

2. Cranial nerves group at several locations3. Cranial nerves are in contact with the meninges and skull base

– CN 6 is particularly affected by meningitis, NPC and raised ICP due to its long intracranial course

4. Cranial nerves behave as peripheral nerves and are thus affected in peripheral neuropathies– Most peripheral neuropathies affect limbs, but GBS/MFS can affect

cranial nerves first

Approach

• Unilateral vs Bilateral

• UMN vs LMN 7

• Isolated vs group vs random

• Long tract signs

Cranial nerve groups

• Cavernous sinus: 3, 4, V1, 6 (sometimes V2)

• Orbital apex: Cavernous sinus + CN 2

• Cerebello-pontine angle: 5, 6, 7, 8 (Vestibular schwannoma/meningiomas)

• Jugular foramen: 9, 10, 11, 12

Cranial Nerve Innervation

• Besides Facial Nerve (lower half of motor nucleus) and Hypoglossal nerve, all other cranial nerve nuclei have bilateral innervation.

DDx for eye movement problems

• Isolated 3– Medical: Usually DM

– Surgical: Usually PCA aneurysm

• Isolated 4– Usually congenital, unmasked when the squint

decompensates

• Isolated 6– Usually DM, but look for skull base, cavernous sinus,

meningeal and ICP causes first

• Complex ophthalmoplegia– Consider MG and thyroid eye disease among other ddx

Tips

• CN 3 carries parasympathetic fibres on the outside, leading to a blown pupil when compressed but a normal pupil when ischemic (surgical vs medical 3rd)

• CN 6 has a long intracranial course and is compressed by raised ICP

Visual Fields

Brainstem rules of 4• 4 Medial structures

– Medial lemniscus (DCML)

– Motor pathway (pyramidal pathway)

– Motor nuclei of 3, 4, 6 and 12

– Medial Longitduinal Fasciculus (MLF)

• 4 Side structures– Spinothalamic

– Sensory nucleus of 5

– Sympathetic nerves

– Spinocerebellar tract

Misc.

• Radiation to the neck for NPC is a cause for cranial neuropathies, especially bilateral cranial neuropathies. Consider it when the deficits fit individual nerves but don’t localisewell anatomically

Eye movements

Eyes

Eyes

• 6th nerve palsy

– Recent onset with early morning headache and vomiting?

– Tinnitus, sensorineural hearing loss and vertiginous giddiness?

– With contralateral limb weakness?

Eyes

Eye

• Complete left sided eye paralysis (3, 4, 6) with ? Failure of depression of right eye

– With numbness over left side of face?

– Patient is NPL?

Eye

Eye

• 3rd nerve palsy

– With a longstanding history of DM and a normal pupil?

– With a blown pupil?

– With contralateral hemiplegia?

Cortical signs

• Dominant Cortex– Language (Aphasia)– Apraxia– Gerstmann Syndrome (Dominant inferior parietal lobe)

• Writing (Dysgraphia)• Calculation (Dyscalculia)• Finger agnosia• Left-right disorientation

• Nondominant Cortex– Neglect– Dressing (Dressing Apraxia)– Construction/Drawing (Constructional Apraxia)– Stereognosis

• Frontal Lobe– Personality changes– Failure to plan– Contralateral gaze preference– Primitive reflexes– Disinhibition

Sensory System

Sensory System

Sensory System

Important features of numbness1. If there is weakness, approach as a weak patient

with sensory symptoms

2. Modalities affected

– Different modalities between limbs: Brown Sequard

– Dorsal columnar loss: bear in mind SCDC and syphilis

3. Distribution of loss

4. Symmetry of loss

– Peripheral neuropathies tend to be more symmetrical

Constellations

Pattern Distal Nerve distribution Nerve distribution

Limbs - Upper Both

Ddx

1. Peripheral Neuropathy

(Sensory PN, Pure SFSN etc.)

2. Cervical myelopathy3. SCDC

4. Demyelinating diseases

1. Median/Radial/Ulnar neuropathy

2. ? Brachial Plexopathy

1. Mononeuritismultiplex

2. Sensoryneuronopathy

Constellations

Pattern Dermatomal Dermatomal

Limbs Upper Lower

Ddx1. Cervical radiculopathy2. Cervical myelopathy

1. Acute Myelopathies2. Cord

transection/transversemyelitis

Case 1

Mr Darren Tan

Stem

• Mr Darren Tan is a 62 year old gentleman who presents with a 3 week history of leg weakness. Please examine the patient’s lower limbs.

Physical examination: Inspection

• Patient appears alert and comfortable at rest

• No signs of muscle wasting, muscle bulk in both legs appears symmetrical

• No fasciculations

Physical examination: Tone

• Increased tone bilaterally

• Presence of clonus bilaterally

Physical examination: Reflexes

• Bilateral brisk knee-jerk reflexes

• Bilateral brisk ankle-jerk reflexes

• Bilateral upgoing plantar reflexes

Physical examination: Power

• R+L Hip flexion 2/5

• R+L Hip extension 2/5

• R+L Knee flexion 2/5

• R+L Knee extension 2/5

• R+L Ankle dorsiflexion 2/5

• R+L Ankle plantarflexion 2/5

• R+L Big toe extension 2/5

• R+L Big toe flexion 2/5

Physical examination: Sensation

• Widespread loss of pin-prick, fine touch and vibration sensation below the hips

• Loss of proprioception bilaterally

Physical Examination: Summary

• Bilateral increased tone and clonus

• Bilateral brisk knee-jerk, ankle-jerk reflexes and upgoing plantar reflexes

• Bilateral weakness of all lower limb muscles with power of 2/5

• Bilateral loss of pain, fine touch, vibration and proprioception

Gait + UL Examination

• Unable to ambulate• Absence of pronator drift• Biceps reflex normal• Triceps reflex normal• Brachioradialis reflex normal• Shoulder abduction 5/5• Finger flexion 5/5• Finger abduction 5/5• Gross sensation intact

Where is the lesion?

• Anterior Horn Cell?• Plexus?• Peripheral nerves?• Neuromuscular junction?• Muscles?

• Cortex?• Subcortex?• Brainstem?• Spinal cord?

Spinal Cord!!!!!!

• Lesion likely between T1 – L1

• Complete examination by requesting to perform abdominal reflexes, digital rectal examination.

Case 2

Mr Ming Shan

Stem

• Mr Ming Shan is a 40 year old male who presents with weakness of the arms. Please examine the patient’s upper limbs.

Physical examination: Inspection

• Patient appears alert and comfortable at rest

• No signs of muscle wasting, muscle bulk in both legs appears symmetrical

• No fasciculations

Physical examination: Tone

• Pronator drift present

• Normal tone bilaterally, no spasticity/rigidity

Physical examination: Reflexes

• Biceps reflex normal

• Triceps reflex normal

• Brachioradialis reflex normal

Physical examination: Power

• R Shoulder abduction 3/5• L Shoulder abduction 4/5• R+L Shoulder adduction 5/5• R+L Elbow flexion 4/5• R+L Elbow extension 5/5• R+L Wrist flexion 5/5• R+L Wrist extension 5/5• R+L Finger flexion 5/5• R+L Finger abduction 5/5

Physical examination: Sensation

• Normal pin-prick, fine touch, vibration and proprioception sensation

Physical Examination: Summary

• Normal tone, reflexes, sensation

• R Shoulder abduction 3/5

• L Shoulder abduction 4/5

• R+L Shoulder adduction 5/5

• R+L Elbow flexion 4/5

Cerebellar + Cranial Nerve + LL Examination

• Dysmetria?

• PEARL

• Presence of diplopia in all gaze-directions

• Patient unable to give a wide smile

• LL reflexes all normal

• 3/5 weakness in hip flexion, knee extension

• Gross sensation of LL intact

Where is the lesion?

• Neuromuscular junction?• Muscles?

• Cortex?• Subcortex?• Brainstem?• Spinal cord?• Anterior Horn Cell?• Plexus?• Peripheral nerves?

Characteristics of MG

• Weakness in muscles is more marked in the evening.

• Muscle weakness which increases with exercises and is painless

• Associated with other autoimmune conditions such as thyrotoxicosis, diabetes mellitus, rheumatoid arthritis etc.

• Can sometimes be caused by D-penicillamine

Unilateral ptosis

• Myasthenia gravis• Horner’s syndrome

– Lung apex (pancoast tumour)– Neck (carotid artery dissection)– T1 pathology– Lateral medullary/pontine syndrome

• CN III palsy– Single nerve lesion– Cavernous sinus / superior orbital fissure / orbital apex syndrome– Midbrain lesions

• Myotonic dystrophy• Congenital

Bilateral ptosis

• Myasthenia gravis

• CN III nuclear lesions

• Myotonic dystrophy

• Congenital

Case 3

STEM

This is your pediatrics short-case station.

Jennifer, 15y/o Chinese adolescent, has had multiple hospital admissions for urinary tract infections. Please perform a neurological examination of her lower limbs.

Physical Examination: Inspection

• Cheerful, alert and comfortable

• No signs of dysmorphism, appropriate growth

• No physical abnormalities

• Left BKA, Right AFO

• No fasciculations noted

• Customized motorized wheelchair by bedside

Physical Examination: Tone

• Decreased tone; floppiness

Physical Examination: Reflexes

• Absent knee-jerk reflex

• Absent ankle-jerk reflex

• Down-going plantars

Physical Examination: Power

Bilateral hip extension: 0/5

Bilateral hip flexion: 5/5

Bilateral knee extension: 0/5

Bilateral knee flexion: 0/5

Right ankle dorsiflexion: 0/5

Right ankle plantarflexion: 0/5

Right big toe extension: 0/5

Right big toe flexion: 0/5

Physical Examination: Sensation

• Intact sensation of all modalities when tested over bilateral mid-thighs

• Loss of sensation of all modalities when tested over bilateral medial knees, right medial malleolus, right interdigital web-space of big and second toe and right lateral sole of foot

Physical Examination: Summary

• Left BKA, Right AFO

• Decreased tone; floppiness

• Absent knee-jerk and ankle-jerk reflexes, down-going plantars

• Bilateral weakness of all LL muscles from knee distally + hip extension with power of 0/5

• Bilateral loss of sensation of all modalities from medial knees distally

Physical Examination: Back & Abdomen

• Midline scar

• Oblique scar along left flank

• No vertebral abnormalities

• No pressure sores

Physical Examination: Others

• Upper limbs?

• Cerebellar examination?

• Cranial nerves?

• Head examination?

• Developmental assessment?

Case 4

STEM

This is your IM short-case station.

Mr Chander, 45y/o Chinese, presents to the A&E with complaint of difficulty eating. Please perform a cranial nerve examination.

Physical Examination: Inspection

• Alert and comfortable, communicable

• Vitals stable

• Presence of left facial droop with loss of left nasolabial fold and smoothening of left forehead creases

Physical Examination: CN V, VII, VIII

• Facial sensation fully intact

• Inability to raise left eyebrow, inability to bury left eyelashes, drooping of left angle of mouth when asked to smile, asymmetrical appearance when asked to puff up cheeks

• Hearing intact

Physical Examination: CN I, II, III, IV, VI

• PEARL (direct and consensual)

• Full extra-ocular movements, no RAPD

Physical Examination: CN IX, X, XI, XII

• No dysarthria/dysphonia, uvula central

• No tongue deviation

• Power of SCM and trapezius full

Physical Examination: Summary

• Presence of left facial droop with loss of left nasolabial fold and smoothening of left forehead creases

• Inability to raise left eyebrow, inability to bury left eyelashes, drooping of left angle of mouth when asked to smile, asymmetrical appearance when asked to puff up cheeks

• Other CN intact

Physical Examination: Others

• Upper limbs? Lower limbs?

• Head and neck examination?

• Acoustic reflex?

• Taste and oral examination?

• Assessing complications?

Review: Approach to CN palsies

• CN pathologies can happen in:

– Isolated

– Together as a group (rules of 4)

– No pattern

– Together with signs in UL and LL

Rules of 4

Cranial nerves involved Pathology/lesion

III, IV, V1, V2 Cavernous Sinus Syndrome

III, IV, V1, VI Superior Orbital Fissure Syndrome

V, VII, VIII, cerebellum Cerebellopontine angle lesion

IX, X, XI, XII Lesions in the posterior fossa

Level of brainstem Cranial nerves

Midbrain/diencephalon I, II, III, IV

Pons V, VI, VII, VIII

Medulla IX, X, XI, XII

Review: Approach to CNVII

Review: Approach to CNVII

• Intracranial (intratemporal vs extratemporal) vs extracranial

• 5 P’s (pons, posterior fossa, petrous bone, parotid, peripheries)

Case 5

STEM

This is your IM short-case station.

Mr Lim was brought to the A&E by NH staff for ?weakness. He has background dementia with BPSD and is uncommunicative. Please perform a neurological examination of his lower limbs

Physical Examination: Inspection

• Resting in bed, comfortable, smiling inappropriately, stable vitals

• Symmetrical; no fasciculations

Physical Examination: Tone

• Increased tone/rigidity over right lower limb with presence of clonus

• Normal tone of left lower limb

Physical Examination: Reflexes

• Brisk knee-jerk and ankle-jerk reflexes and up-going plantars for right lower limb

• Normal reflexes and down-going plantars for left lower limb

Physical Examination: Power

Right/left hip extension 3/5; 5/5

Right/left hip flexion 3/5; 5/5

Right/left knee extension 3/5; 5/5

Right/left knee flexion 3/5; 5/5

Right/left ankle dorsiflexion 3/5; 5/5

Right/left ankle plantarflexion 3/5; 5/5

Right/left big toe extension 3/5; 5/5

Right/left big toe flexion 3/5; 5/5

Physical Examination: Sensation

• Intact sensation of all modalities of lower limbs

Physical Examination: Cerebellum

• Heel-shin test positive

• Patient not keen to ambulate

Physical Examination: Summary

• Increased tone/rigidity over right lower limb with presence of clonus

• Brisk knee-jerk and ankle-jerk reflexes and up-going plantars for right lower limb

• Diminished power of 3/5 of right lower limb

• Intact sensation of all modalities of both LLs

Physical Examination: Others

• Upper limbs?

• Cranial nerves?

• Cardiovascular examination?

Discussion

• What if he presented with headache, nausea and vomiting with weakness?

• What if he presented with right-sided facial weakness with left-sided hemiparesis?

• What if he presented with right-sided hemiparesis and expressive aphasia?

#1: Where is the lesion?

Where Upper/Lower

Symmetrical/Asymmetrical

Unilateral/Bilateral

Sensory Hallmarks

Cortex Upper Asymmetrical Unilateral +/- CrossedCortical Signs

Subcortical Upper Asymmetrical Unilateral +/- LacunarSyndromes

Brainstem Upper Asymmetrical Unilateral +/- Crossed Hemiparesis

Spinal Cord Upper Symmetrical Bilateral -(SS lvl)

Cord syndromes, ARU

Anterior Horn Cell

Mixed Symmetrical Bilateral/Unilateral

+ Fasciculations, CNs affected

Plexus, Roots

Lower Asymmetrical Unilateral - Dependent on levels affected

Peripheralnerves

Lower Symmetrical Bilateral +/- Length-dep distal weakness

NMJ Lower Symmetrical Bilateral + Prox weakness, fluctuating fatig

Muscles Lower Symmetrical Bilateral + Prox weakness,check CN

#2: What is the etiology?

Differential Diagnoses(supporting risk factors)

• Sudden onset– Vascular (stroke)– Trauma– Epilepsy (Todd’s paralysis)

• Subacute onset– Infection (TB abscess, meningitis)– Inflammation (lupus, MS)

• Gradual onset– Degeneration (PD)– Demyelination (MS)– SOL (hydrocephalus, neoplasm)

• Variable onset– Metabolic (hypoglycemia great mimicker of neuro conditions)– Toxic/paraneoplastic

#3: What are the complications?

Complications

• Medical– Contractures, neuropathic ulcers– Complications of prolonged immobilization

• Functional– Body function, activity, participation

• Social– Patient, family, community

• Psychological – Depression, mania

• Financial

Neuro Approaches

• Approach to weakness/numbness

• Approach to hemiparesis

• Approach to spastic/flaccid paraparesis

• Approach to foot drop

• Approach to CN lesions

• Approach to ophthalmoplegia

• Approach to ptosis

• Approach to movement disorders