Motor Neurone Disease Flashcards
What is motor neurone disease
A cluster of neurodegenerative diseases , characterised by a selective loss of neurons in the motor cortex, cranial nerve nuclei and anterior horn cells
What differentiates motor neurone disease from MS and MG
Upper and lower motor neurons can be affected, but there is no sensory loss or sphincter distrubance
- differing from MS
It also never affects eye movements
- differing from myasthenia
What are the four clinical patterns of motor neurone disease
1) ALS/amyotrophic lateral sclerosis
- loss of motor nuerons in the motor cortex and the anterior horn of the cord
- combined UMN and LMN signs
2) Progressive bulbar palsy
- only affects cranial nerves 9 to 12
- causes bulbar and corticobulbar palsy
3) Progressive muscular atrophy
- anterior horn cell lesion, LMN signs only
- affects distal muscle groups before proximal
4) Primary lateral sclerosis
- loss of Betz cells in the motor cortex
- mainly UMN signs, marked spastic leg weakness and pseudobulbar palsy
- no cognitive decline
What is bulbar palsy?
Denotes diseases of the nuclei of cranial nerves 9-12 in the medulla.
Clinical features are that of a LMN lesion of tongue and muscles of talking and swallowing
- flaccid, fasciculating tongue
- jaw jerk can be normal or absent
- quiet, hoarse or nasal speech
Causes of bulbar palsy
Motor neurone disease Guillain-Barre syndrome Polio Myasthenia gravis Brainstem tumours Central pontine myelinolysis
What is pseudobulbar palsy
UMN lesion of muscles of swallowing and talking
More common than bulbar palsy
Clinical features
- slow tongue movements
- slow and deliberate speech
- increased jaw-jerk
- increased pharyngeal and palatal reflexes
- pseudobulbar affect (PBA) (weeping unprovoked by sorrow or mood-incongruent giggling)
PBA is also seen in MS, Wilson’s, Parkinson’s disease, dementia. nitrous oxide use and head injury
Causes of pseudobulbar palsy
Due to bilateral lesions above the mid-pons (e.g. corticobulbar tracts)
- MS
- motor neurone disease
- stroke
- central pontine myelinolysis
How does motor neurone disease present?
Think of MND in those >40 years with
- stumbling, spastic gait
- foot drop with/without proximal myopathy
- weak grip (can’t turn door handles)
- weak should abduction (washing hair is hard)
- aspiration pneumonia
Look for UMN signs such as
- spasticity, brisk reflexes and upgoing plantars
Look for LMN signs such as
- wasting, fasciculations of tongue, abdomen, back and thighs
Frontotemporal dementia occurs in around 25% of MND patients
How is motor neurone disease diagnosed?
Revised El Escorial diagnostic criteria for ALS
- definite: lower and upper motor neuron signs in three regions
- probable: lower and upper motor neuron signs in two regions
- probable with lab support: lower and upper motor neuron signs in 1 region, OR upper motor neuron signs in 1 or more regions + EMG shows acute denervation in 2 or more limbs
- possible: lower and upper motor neuron signs in one region
- suspected: upper or lower motor neuron signs only in 1 or more regions
Brain/cord MRI excludes structural causes
LP helps exclude inflammatory causes
Neurophysiology detects subclinical denervation and help exclude mimicking motor neuropathies
Prognosis of motor neuron disease
Poor - <3 years in 50% of patients
Management of motor neuron disease
MDT approach - neurologist, palliative nurse, hospice, physio, occupational therapist, speech therapist, dietitian and social services - orchestrated by GP Riluzole - inhibits glutamate release - improves survival Supportive/symptomatic treatment
Describe the supportive/symptomatic treatment in motor neuron disease
Excess saliva
- positioning, oral care and suctioning
- antimuscarinic or glycopyrronium bromide
- botulism toxin A may help
Dysphagia
- blend food
- gastrostomy (discuss early on)
Spasticity
- exercise, orthotics
- baclofen/gabapentin
Communication difficulties
- provide augmentative and alternative communication equipment
End-of-life care
- involve palliative team from diagnosis
- opioids to relive breathlessness and discuss non-invasive ventilation
