Definition please
A group of several disorders where motor neurons are affected, both UPPER and LOWER.
NO SENSORY LOSS(differentiates from MS and polyneuropathies)
MND also never affects eye movements (different from myasthenia gravis)
Cause is unknown
Epidemiology
very rare
M:F=3:2
Mean onset = 60
often fatal 2-3 years
Types of MND
- Amyotrophic Lateral Sclerosis (ALS) =50%
- loss of motor neurons in motor cortex and anterior horn of spinal cord thus UMN signs and LMN wasting bilaterally
- UMN and LMN in 3 locations
- Bowel, bladder and eyes spared
- split hand sign (loss of pincer grip due to wasting) - Progressive bulbar palsy (10%)
- only affects CN IX-XII
- Dysphasia, Dysphagia +/- flaccid fasciculating tongue - Progressive Muscular atrophy (10%)
- ant horn lesion only, thus no UMN signs
- Affects distal muscles before proximal - Primary lateral sclerosis
- Loss of betz cells in motor cortex this mostly UMN with marked spastic leg weakness and pseudobulbar palsy
History PC
> 40 years Stumbling gait, foot drop Wekness Aspiration pneumonia Speech difficulty Swallowing difficulty Fronto-temporal dementia
Examination
Upper and Lower Neuro and CN exam
UMN signs - spacticity, brisk reflexes, upgoing plantar
LMN signs - wasting, fasciculations
Dysphagia and dysphasia
WEAKNESS
Memory impairment
Differential Diagnosis for NMD?
Peripheral neuropathies
Myopathy
Myesthenia gravis
Brain or spinal cord lesion
Investigations
Brain/cord MRI to exclude structural causes
LP to exclude inflammatory causes
Nerve conduction studies to detect subclinical denervation and help exclude mimicking motor neuropathies
Management
Non-Pharm
- MTD input
- blend food etc
Pharmacological
- Antiglutamatergic drugs - gives 3 months for $$$
- Amytriptyline for drooling
- analgesia for joint pain
- non-invasive ventilation
