Neurology JC022: Where Is The Lesion? (2) Symptoms And Signs In Neurology Flashcards

1
Q

Spinal cord

A

Cervical: C1-8
Thoracic: T1-12
Sacral: S1-5

Plexuses (nerve roots join together)
- Brachial plexus (upper limbs): **C5-T1
- Lumbosacral plexus (lower limbs + pelvic structures): **
L1-S3

Conus medullaris: End at ***L1/2 spinal level —> Cauda equina (nerve roots of lower spinal cord)

Ventral root: Motor (anterior horn cells)
Dorsal root: Sensory (1st order neuron in dorsal root ganglion)
Spinal root: Ventral + Dorsal root

Radiculopathy: Nerve root lesion
Myelopathy: Cord lesion

Revision: Organisation of Spinal nerves
Spinal cord
—> Spinal nerve roots (Dorsal + Ventral root)
—> Spinal nerve
—> Branch (Dorsal + Ventral rami + Rami communicantes (gray / white rami —> leads to sympathetic ganglion))

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2
Q

Pyramidal system

A
  • Use to find out location of lesion
  • Corticobulbar
  • Corticospinal

UMN lesion (**Primary motor cortex —> Cranial motor nuclei (brainstem) / Anterior horn cells (spinal cord)):
- no early wasting
- **
weakness (spastic paresis)
- **↑ tone (spasticity)
- **
hyperreflexic
- ***Babinski’s sign

LMN lesion (Cranial motor nuclei (brainstem) / Anterior horn cells (spinal cord) —> NMJ):
- **wasting +/- **fasciculation
- **weakness (flaccid paresis)
- ↓ tone (flaccid)
- **
hyporeflexic / areflexic

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3
Q

Primary motor cortex homunculus

A

Medial side of cortex: Contralateral Leg
Lateral side of cortex: Contralateral Hands, Head and Neck

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4
Q

General localisation

A
  1. Pyramidal system (Corticospinal / Corticobulbar)
    Weakness depending on level of lesion:

Brainstem
- specific CN deficit (i.e. head and neck)
- **UMN signs below level of lesion (e.g. spastic quadriplegia)
- other signs depending on intrinsic structures in Brainstem (e.g. MLF: **
internuclear ophthalmoplegia, sympathetic tract: ***ipsilateral Horner)

Spinal cord
- head and neck spared
- above C5: **UMN signs below level of lesion (e.g. spastic quadriplegia)
- C5-T1: **
LMN signs upper limb, **UMN signs lower limb
- T2-T12: **
sensory level on trunk, upper limbs spared, UMN signs lower limb
- L1-S5: upper limbs spared, **LMN signs lower limb, **sphincter disturbance (Cauda equina affected)

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5
Q

Myotomes

A

Diaphragm: ***C3-5

Hands / Arms:
Deltoid: C5-6
Biceps, Brachialis: C5-
6
Triceps: C6-**7
Extensor carpi radialis longus + breves: C6-7
Instrinsic hand muscles: **
C8-T1

Legs:
Iliopsoas: L1-2
Adductor longus + brevis: L2-3
Quadriceps: **
L3-4
Hamstrings: L4-5
Tibialis anterior: **
L4-5
Gastrocnemius, Soleus: S1-2
Extensor hallucis longus: L5-S1

Anal sphincter
Sphincter ani externus: ***S2-4

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6
Q

Dermatome

A

No C1 dermatome (∵ no sensory root)
Head:
- Face: CN5
- Occipital: Spinal nerves (C2, C3)
- Shoulder: Spinal nerves (C4)

Dermatomes overlap!

Special dermatomes:
**T10: Umbilicus
**
L1: Inguinal region

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7
Q

***Spinal cord

A

Spinal cord level
- Motor:
—> **At level of lesion: LMN sign
—> **
Below level of lesion: UMN sign
—> Above level of lesion: Unaffected
- Sensory: ***Dermatomal sensory level
- Different specific deficits depending on area of affected spinal cord

Spinal root
- Motor: **LMN signs
- Sensory: **
Dermatomal sensory level
- Cauda equina (multiple root levels, sphincter affected)

Plexus:
- ***Multiple nerves affected
- Motor: LMN signs
- Sensory: Dermatomal sensory level

(Dermatomal sensory level: intact dermatome level located immediately above the first dermatome level with impaired or absent light touch or pin prick sensation)

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8
Q

***Peripheral nerves

A
  • ***LMN signs
  • Usually all sensory modalities affected but some more than others (e.g. in DM)

Generalised neuropathy (i.e. **Polyneuropathy)
- Motor:
—> LMN signs in upper + lower limbs
—> **
Distal > Proximal weakness
—> Respiratory muscles may be affected (e.g. **Guillain-Barré syndrome)
- Sensory: **
Glove + Stocking sensory deficit (唔再係Dermatomal sensory level, ∵ length-dependent, longest peripheral nerve affected first, ∴ sphincters relatively spared due to innervation by short nerves)

**Isolated compressive neuropathy
- Motor: LMN signs of **
specific muscle group affected
- Sensory: ***Dermatomal sensory deficit (of nerve distribution) (同Polyneuropathy唔同)

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9
Q

NMJ

A
  • Weakness (eyelid, external ocular muscles, respiratory, pharyngeal, neck, jaw, limbs)
  • ***No sensory deficit
  • **Diurnal variation (weakness during later of day) + **Fatiguability

E.g. Myasthenia gravis
- **Ptosis
- **
Thymoma
- **Dysphagia: aspiration pneumonia
- **
Ventilatory failure

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10
Q

Muscle (Myopathy)

A
  • Weakness (***Proximal > Distal, ∵ more muscle in proximal area) —> difficulty climbing up stairs / standing up from squatting
  • Symmetrical
  • ***No sensory deficit
  • may not have wasting
  • may have Muscle ***Pain + Tenderness

E.g. Musculodystrophy

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11
Q

What is the lesion?

A

Congenital / Developmental
- younger age group
- positive family history
- consanguineous birth

Vascular
- **sudden onset
- **
transient nature
- risk factors of vascular disease

Degenerative
- older age group
- **gradual onset
- **
progressive course

Neoplastic / Paraneoplastic
- **insidious onset
- **
progressive course
- other generalised features e.g. loss of weight / appetite

Demyelinating
- ***exacerbating / remitting course

Inflammatory (Infective / Autoimmune)
- fever (acute / chronic)
- general malaise
- ***signs of infection / inflammation e.g. LN, skin rash, joint pains

Metabolic / Toxic
- precipitating course e.g. drugs, exacerbation of previous systemic disorder (e.g. liver / renal encephalopathy)
- encephalopathy

Trauma / Physical
- cause and effect usually seen

Location of lesion, Spectrum, Pattern of clinical features also give clues to nature of lesion

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