Motor Neuron Disease

Question 1

def

Answer 1

cluster of degenerative diseases characterised by selective loss of neurons in motor cortex, cranial nerve nuclei, anterior horn cells

Question 2

does MND affect upper or lower motor neurons

Answer 2

both

Question 3

what distinguishes MND from MS and polyneuropathies

Answer 3

no sensory loss or sphincter disturbance

Question 4

what distinguishes MND from myasthenia gravis

Answer 4

MND never affects eye movements

Question 5

what are the four different types of MND

Answer 5

1 amyotrophic lateral sclerosis (ALS) (most common)
2 progressive bulbar palsy
3 progressive muscular atrophy
4 primary lateral sclerosis

Question 6

what are the features of amyotrophic lateral sclerosis (ALS)

Answer 6

loss of motor neurons in motor cortex and anterior horn

weakness + UMN signs (babinski positive)
LMN wasting or fasciculations

Question 7

what are the features of progressive bulbar palsy

Answer 7

only affects cranial nerves IX-XII

Question 8

what are the features of progressive muscular atrophy

Answer 8

anterior horn lesion only therefore no UMN signs

affects distal muscle groups before proximal

Question 9

what are the features of primary lateral sclerosis

Answer 9

loss of Betz cells in motor cortex

therefore mainly UMN signs + marked spastic leg weakness

Question 10

aetiology

Answer 10

unknown (free radical damage implicated)

Question 11

pathology

Answer 11

progressive motor neuron degeneration and death with gliosis replacing lost neurons

Question 12

what is gliosis

Answer 12

change in glial cells in response to damage of the CNS

Question 13

what are common types of glial cells

Answer 13

astrocytes
microglia
oligodendrocytes

Question 14

associations

Answer 14

MND is associated with frontotemporal lobar dementia from proganulin mutations

Question 15

epi

Answer 15

males>females

common in >60yrs

Question 16

history

Answer 16

limb weakness
speech disturbance (slurring or reduction in volume)
swallowing disturbance (choking on food)
behavioural changes (disinhibition)

Question 17

examination

Answer 17

combined UMN + LMN signs which affect several regions asymmetrically

Question 18

what LMN features

Answer 18

muscle wasting
fasciculations
increased tone
decreased/absent reflexes

Question 19

what are UMN features

Answer 19

increased tone
brisk reflexes
babinski positive

Question 20

what would be expected on sensory examination of MND

Answer 20

normal

Question 21

investigations

Answer 21

investigations are aimed to confirm the diagnosis of MND by providing evidence of combined UMN + LMN loss

1 bloods
-raised CK
2 MRI (brain/cord)
-exclude structural causes
3 LP
-exclude inflammatory causes
4 EMG

Question 22

what are you looking for on an EMG

Answer 22

features of acute and chronic denervation with giant motor unit APs in >1 limb

Question 23

what is bulbar palsy

Answer 23

diseases of the nuclei of CNs IX-XII in the medulla

Question 24

what are signs of bulbar palsy

Answer 24

UMN lesion of the tongue + muscles of talking + swallowing

• fasciculating tongue
• nasal speech
• jaw jerk is normal/absent + gag reflex is decreased

Question 25

what are causes of bulbar palsy

Answer 25

guillain barre
myasthenia gravis
brainstem tumours

Question 26

what is corticobulbar palsy

Answer 26

UMN lesion of muscles of talking + swallowing due to bilateral lesions above the mid pons

Question 27

what are causes of corticobulbar palsy

Answer 27

MS
MND
stroke

Question 28

what are signs of corticobulbar palsy

Answer 28

slow tongue movements
slow deliberate speech
increased jaw jerk + gag reflex is increased

the pseudobulbar affect which is emotional incontinence:

• crying without provoked sadness
• giggling without reason

Question 29

what criteria is used to diagnose ALS

Answer 29

Revised EI Escorial diagnostic criteria

Question 30

what are the features of the Revised EI Escorial diagnostic criteria

Answer 30

definite:
-LMN + UMN signs in 3 regions
probable:
-LMN + UMN signs in 2 regions
possible:
-LMN + UMN signs in 1 region