Case 1: Mandy Wallsmith Pt 1 - Transverse Myelitis

Spinal Cord: Grey Matter

Centre

Surround central canal containing CSF

Contain:

• Cell bodies

• Dendrites

• Proximal axons

Parts:

• Ventral horn

• Dorsal horn

• Lateral horn

Spinal Cord Grey Matter: Ventral Horn

Anterior grey column

Contain:

• Motor neuron cell bodies

  • Alpha/lower motor neurons (LMN)

    • Axons → Periphery

    • Innervate: Skeletal muscle = Contraction

  • Gamma motor neurons

    • Innervate: Muscle spindles = Stretch sensitivity

• Renshaw Cells: Inhibitory neurons

Spinal Cord Grey Matter: Dorsal Horn

Posterior grey column

Contain: Sensory neuron cell bodies

• Spinal reflexes

Spinal Cord Grey Matter: Lateral Horn

Lateral grey column

Contain:

• Sympathetic neuron preganglionic cell bodies

• Clarke Nucleus: Posterior thoracic

  • Unconscious proprioception

Spinal Cord: White Matter

Surround grey matter

Contain:

• Myelinated axons

• Nerve fibre bundles

No dendrites

Spinal Cord White Matter: Myelinated Axons

Tracts/fasciculi

Sensory (ascending) + motor (descending) tracts transmit signals between CNS and PNS

Spinal Cord White Matter: Nerve Fibre Bundles

Funiculi

• Anterior

• Lateral

• Posterior

Spinal Nerves

Exit spinal canal → Innervate periphery

Parts:

• Roots

• Rami

Spinal Nerves: Roots

Nerve exiting intervertebral foramina

Anterior: Motor/efferent fibres

Dorsal: Sensory/afferent fibres

• Dorsal Root Ganglia: Outside vertebral column

Spinal Nerves: Rami

Spinal nerve sections + sensory and motor fibres

Ventral: Anterior

Dorsal: Posterior

Spinal Cord: Sensory Systems

Ascending tracts

2 major conscious sensation pathways

1. Dorsal Column-Medial Lemniscus (DCML) System

2. Anterolateral (Spinothalamic) System

2 major unconscious sensation pathways

• Spinocerebellar tract

• Spinoolivary tract

Spinal Cord Sensory: DCML System

3 neurons

Transmit:

• Proprioception

• Epicritic sensation

  • Fine touch

  • Vibration

  • Pressure

DCML System: 1st Order Neuron

Cell body in dorsal root ganglia

• Sensory nerve fibres

Axons → Spinal cord dorsal column (white matter) → Ascend ipsilaterally to medulla oblongata

DCML System: 2nd Order Neuron

Cell body in dorsal column nuclei (medulla)

Axons decussate in medulla + ascend contralaterally in medial lemniscus (brainstem)

DCML System: 3rd Order Neuron

Somatosensory cortex

Spinal Cord Sensory: Spinothalamic System

3 neurons

Transmit:

• Pressure (anterior)

• Protopathic sensation

  • Temp (lateral)

  • Pain (lateral)

  • Crude touch (anterior)

Spinothalamic System: 1st Order Neuron

Cell body in dorsal root ganglia

• A-delta and C fibres

Axons → Spinal cord → Synapse in dorsal horn (grey matter) (1-2 spinal levels above)

Spinothalamic System: 2nd Order Neuron

Cell body in dorsal horn

Axons decussate in spinal cord + ascend contralaterally

Spinothalamic System: 3rd Order Neuron

Somatosensory cortex

Spinal Cord: Unconscious Sensation

Transmit: Proprioception

Spinal Cord: Motor Systems

Descending tracts

General:

• Upper Motor Neuron (UMN): Descending inhibition

  • Inhibit excess firing from LMNs

• Lower Motor Neuron (LMN): Excitatory signals

  • Constant excitatory neuron firing = Spinal cord reflexes

2 major types

• Corticospinal (Pyramidal) Tract

• Extrapyramidal Tracts

Spinal Cord Motor: Pyramidal Tract

2 neurons

Control: Voluntary movement of contralateral side

Spinal Cord Motor: Extrapyramidal Tracts

2 neurons

Control: Motor neurons

• Involuntary movement (reflexes)

• Muscle tone

• Facial muscles

Pyramidal Tract: 1st Order Neuron

Cell body in motor cortex

Types:

• Upper motor neuron

  • Axons descend ipsilaterally

• Lateral corticospinal tract

  • Axons decussate in medulla oblongata → Descend contralaterally in spinal cord

• Anterior corticospinal tract

  • Axons decussate at innervation level

Synapse in ventral horn (grey matter)

Pyramidal Tract: 2nd Order Neuron

Cell body in ventral horn

LMN → NMJs

• Upper + lower limbs

Extrapyramidal Tracts: 1st Order Neuron

Different pathways

• Rubrospinal pathway

  • Proprioception

• Reticulospinal tract

  • Posture + tone

• Vestibulospinal tract

  • Ear

• Tectospinal tract

  • Eye

Synapse in ventral horn (grey matter)

Extrapyramidal Tracts: 2nd Order Neuron

Cell body in ventral horn

LMN → End locations depending on tract

Sensory Neuron Dysfunction: Peripheral

Lesions in peripheral nerves (post-rami)

Affect all senses together (pain, temp, touch, vibration, proprioception) in predictable pattern

Peripheral Sensory Neuron Dysfunction: Types

Polyneuropathy: Stocking-glove distribution

• Symmetric sensory loss in toes → Ascend symmetrically to knees → Fingertips

Mononeuropathy: Affect 1 peripheral nerve = 1 nerve territory

Radiculopathy: Dermatome pattern

Sensory Neuron Dysfunction: Central

Lesions in CNS (spinal cord + brain)

No pattern

Central Sensory Neuron Dysfunction: Types

Sensory Level: Sensory loss below spinal cord lesion level

Dissociated: Spinal cord tract lesion = Affect different sensory modalities

• Spinothalamic: Pain/temp

• DCML: Vibration/proprioception

Bowel/bladder dysfunction

Motor Neuron Dysfunction: UMN

Lesion before ventral horn

• Loss of LMN inhibition

Normal muscle

Central paresis: No voluntary movement +

• Increased tone, spasticity (uncontrolled movement), clonus

• Decreased power

• Hyperreflexia

Detrusor muscle hyperreflexia + incoordination

Upgoing Babinski reflex (abnormal)

• Big toe up

• Toes 2-5 down

Motor Neuron Dysfunction: LMN

Lesion between ventral horn + muscle

• Loss of excitatory firing

Muscle atrophy + fasciculation (twitching)

Peripheral paresis: No voluntary movement +

• Decreased tone

• Decreased power

• Hyporeflexia/areflexia

Overflow incontinence

• Bladder overfills = Involuntary urine leakage

Downgoing Babinski reflex (normal)

• Toes down

Transverse Myelitis: Description

Acute/subacute inflammatory myelopathy (neurologic disorder from spinal cord injury)

• Affect ascending + descending neural pathways

Transverse Myelitis: Epidemiology

Bimodal peak incidence

• 10-19 years

• 30-39 years

Transverse Myelitis: Etiology

Idiopathic

Parainfectious

• Enterovirus

• EBV

• CMV

• B. burgdorferi (Lyme disease)

CNS demyelination disorders

• MS

Paraneoplastic syndromes

Drugs

• TNF-a inhibitors

• Chemotherapy

Transverse Myelitis: Pathophysiology

Autoantibodies cause… = Neuroinflammation

• Lymphocyte + monocyte collection in spinal cord

• Spinal cord demyelination

• Axon injury

• Astroglial + microglial activation

  • Nonneuronal support cells in CNS

Transverse Myelitis: Clinical Presentation

Onset: Acute/subacute (4 hours to 21 days)

• Spinal shock: Loss/depression of sensorimotor functions + reflexes below injury level

• UMN dysfunction

  • Spasticity

  • Hyperreflexia

  • Upgoing Babinski sign

Progression: Neurological dysfunction

• Motor

  • Paresis

  • Paraplegia

• Sensory

  • Numbness

  • Paresthesias

• Autonomic

  • Bladder/bowel incontinence

  • Sexual dysfunction

Transverse Myelitis: Investigations

Imaging

Lab tests

CSF analysis

Transverse Myelitis Investigations: Imaging

MRI ± gadolinium contrast

• Focal gadolinium-enhancing lesion in spinal cord

• T2-weighted sequence (hyperintensity) = Bright CSF (edema) + adipose tissue (white brain matter)

Transverse Myelitis Investigations: Lab Tests

Serology: Determine cause

• Viral infections

• Syphilis

• HIV abs

Inflammatory markers

• Increased ESR + CRP

Serum abs

• ANA

• RF

• Antiphospholipids abs

Vit B12 + methylmalonic acid (buildup in B12 deficiency)

TFTs: R/O thyroid dysfunction

Transverse Myelitis Investigations: CSF Analysis

Inflammatory markers

• Pleocytosis: Increased cells

• Increased IgG

Oligoclonal Bands: IgG subfractions on electrophoresis = Increased IgG

Cultures

Transverse Myelitis: Acute Treatment

First-Line: High-dose IV corticosteroids

Second-Line:

• Plasmapheresis

• Cyclophsophamide

Supportive care

Transverse Myelitis Acute Treatment: Plasmapheresis

Insufficient corticosteroid response

• Filter plasma from whole blood = Remove autoantibodies

• Replace with donor plasma or albumin solution

Transverse Myelitis Acute Treatment: Cyclophosphamide

Immunosuppressant

Alkylating DNA = Prevent production

Transverse Myelitis Acute Treatment: Supportive Care

Prevent ulcers + thrombosis

Manage complications

• Urinary retention

• Gastroparesis

• Constipation

• Resp failure

Transverse Myelitis: Chronic Treatment

Neurological rehab (physiotherapy)

Treat underlying cause

Transverse Myelitis: Complications

Resp failure

Immobilization complications

• Atelectasis

• DVT

• Pressure ulcer

Dysphagia

GI dysfunction

Osteoporosis

Autoimmune disorders

• Orthostatic hypotension

• Thermodysregulation

• Dysreflexia

MRI Sequences (Results)

T1-Weighted:

• Hyperintense: Fat/adipose tissue (white brain matter)

• Hypointense:

  • Water/CSF/edema

  • Bone

  • Ligaments

  • Tendons

  • Air

T2-Weighted:

• Hyperintense: Water/CSF/edema

• Hypointense:

  • Bones

  • Ligaments

  • Tendons

  • Air