Routine for examination of lower limbs:
Inspect (wasting and fasciculations*, wheelchair/walking aid, PEG)
Tone
Power
Reflexes
Sensation
Coordination
Gait (if patient is able)
If time allows and you suspect MND proceed as follows:
Mouth: tongue wasting and fasciculations
Jaw jerk
Upper limbs: fasciculations, small hand muscle wasting, reflexes
Speech e.g. “How did you get here today?”
Eye movements
Present to the examiner:
I suspect motor neuron disease because of mixed upper and lower motor neuron signs such as:
Wasting and fasciculations
Spastic paraparesis (increased tone bilaterally, pyramidal weakness bilaterally, increased knee reflexes, upgoing plantars and clonus)
Absent ankle reflexes
Tongue wasting and fasciculations
Increased jaw jerk
Dysarthric speech
Sensation was normal
Coordination was in proportion to the weakness
Eye movements were normal
To complete my examination I would like to:
perform full upper limb neurological examination as well as cranial nerves and speech and swallow assessment.
My differential diagnosis includes:
Cervical myeloradiculopathy (would have sensory disturbance)
Multifocal motor neuropathy
Syringomyelia (but would have sensory disturbance)
Friedreich’s ataxia (but would have cerebellar signs and dorsal column sensory loss)
Subacute combined degeneration of the cord (but would have dorsal column sensory loss)
Syphilitic amyotrophy (but would have dorsal column sensory loss)
Other causes of spastic paraparesis (see “Station 3 Spastic Paraparesis”) such as cord compression and demyelination (would have sensory disturbance)
Other causes of anterior horn cell disease such as polio, spinal muscular atrophy
Investigations:
Sats, ABG (respiratory failure), spirometry
MRI to exclude cord/root compression
Nerve conduction studies (to exclude multifocal motor neuropathy) and EMG: denervation and fasciculations and fibrillations.
Lumbar puncture may be indicated to exclude demyelination if unclear clinical picture
Bloods e.g. paraneoplastic screen, syphilis serology, B12
Motor Neuron Disease
This is a progressive degenerative disorder of motor neurons in the motor cortex and corticospinal tract, anterior horn cells of the spinal cord and brainstem.
*Mixture of upper and lower motor neuron signs*
It never affects sensation/cerebellum/vision
Types of MND:
- Amyotrophic lateral sclerosis: Mixed upper and lower motor neurone signs
- Primary lateral sclerosis: Upper motor neurone signs only
- Progressive muscular atrophy: Lower motor neurone signs only
- Progressive bulbar/pseudobulbar palsy
Management
Conservative: physio, OT, SALT, dietician, specialist nurse
Medical: treat infections, anticholinergics, baclofen, NIV, antidepressants, riluzole (antiglutamate), PEG
Written by Dr Sarah Kennedy
Resources used to write this document are listed in the references section of this webpage