Motor Neurone Disease

Question 1

Definition

Answer 1

Motor neurone disease is a cluster of major degenrative diseases characterised by selectve loss of neurones in motor cortex, cranial nerve nuceli and anterior horn cells. Upper Motor neurons and lower motor neurons are affected but there is no sensory loss or sphincter disturbace, thus distinguishing MND from MS

Question 2

Clinical features

Answer 2

Four clinical patterns

Note- no involvement of the sensory system or motor nerves to the eyes and sphincters

• Progressive muscule atrophy -
• Amyotrophic lateral sclerosis 75% -
• Progressive bulbar and pdeudobulbar palsy 25%
• Primary lateral sclerosis-

Question 3

Corticospinal tract

Answer 3

Axial and limb motor

1. Begins in the pre central gyrus (primary motor cortex)
2. Two motor neurons

Question 4

Investigations

Answer 4

• EMG- shows denervation and fibrillation
• FBC, ESR
• biochemistry incluing Ca2+, glucose, T4 and immunoglublins and protiein electrophoresisis
• autoantibody screen
• CXR
• MRI
• TFTs - exclude hyperthyroidism
• Nerve conduction studies - will appear normal. used to exclude multifocal neuropathy
• CSF examination: protein may be slighly increased; >5 cells, markedly elevated protein, oligoclonal bands (MS))
• Ach receptor antibody

there is no diagnostic test. Brain/cord MRI helps exclude structural causes, LP excludes inflammatory ones and neuriophysiology helps detect subclinical denervation and helps exclude mimicking motor neuropathies

Question 5

Diagnostic criteria

Answer 5

Revised El excorial diagnsotic cirteria for ALS

definte- Lower + upper motor neuron signs in 3 regions

Probable- Lower + upper motor neuron signs in 2 regions

Probably with lab support - Lower + upper motor neuron signs in 1 region or upper motor neuron signs in > 1region + EMG shows acute denervation in > 2 limbs

Possible_ Lower + upper motor neuron signs in 1 region

Suspected- Upper or lower motor neuron signs only - in 1 or more regions

Question 6

Treatment

Answer 6

Multi-disciplinary approach - due to MNDs impacable course, its rarity and its frigthening nature

• neurologist, palliative nurse, hospice, physio, speech therapist, dietician, social services
• Antiglutamatergic drugs: Riluzole (prolongs life by three months) - Sodium channel blocker that inhibits glutamate release, slows progression slightly Caution: (LFT increased) SEL vomiting, pulse, somnolence, headache, vertigo
• Drooling: Propantheline 15-30mg; amitriptyline 25-50mg/8h
• Dysphagia: Blend food; Would he or she like a nasogastric tube
• Joint pain and distress: Analgesiac ladder: NSAIDS, then opiods
• Respiratory failure- (aspiration pneumonia and sleep apnoea) - Non invasive ventilation at home in selected patients

Question 7

Primary lateral sclerosis

Answer 7

isolated UMN disorder,

​Progressive spastic tetraparesis

Question 8

Progressive bulbar and psuedobulbar palsy

Answer 8

• from destruction of upper (psudeobulbar palsy) and lower (bulbar palsy) motor neurones in the lower cranial nerves.
• presents as problems with speech and swallowing
• There is dyarthria, dysphgia with wasting, and fasciculations of the tongue

Question 9

Amytrophic lateral sclerosis

Answer 9

• UMN and LMN signs - In the same muscle (fasciculations -LMN) and hyperreflexia (UMN)
• combination of disease of the lateral corticospinal tracts (lateral sclerosis) and anterior horn cells
• producing a progressive spastic tetraparesis or paraparesis with added lower motor neurone signs (wasting and fasculiations)

Question 10

Progressive muscle atrophy

Answer 10

• ​predominantly lower motor neurone lesion of the Upper limbs
• causing weakness, wasting and fasciculation (spontaneous, irrgeular and brief contractions of part of a msucel inthe hands and arms)

Question 11

Differential diagnosis

Answer 11

• Hyperparathyroidism and hyperthyroidism - cause muscle wasting and hyperreflexia
• Psudeopulbular palsy - can be caused by cerebrovascular disease and MS
• Conditions exhibit both UMN signs and LMN signs
  
  • ​cervical spondylitis
  • spinal tumours