Motor neurone disease

Question 1

Signs of MND on examination

Answer 1

Inspection: Wasting and fasciculation, especially tongue fasciculation.
Tone: spastic.
Power: weak.
Reflexes: absent or brisk (mixed UMN and LMN signs in MND).
Sensation is Normal.

Question 2

Completion of an MND exam

Answer 2

Speech: bulbar palsy - nasal speech. Pseudobulbar - hot potato speech.
Jaw-jerk: bulbar - absent, pseudobulbar - brisk.
Eye movements: MND does not involve the eyes.

Question 3

Lesion difference between bulbar and pseudobulbar palsy

Answer 3

Bulbar palsy: Lower motor neurone lesion of CN9, 10 and 12.

Pseudobulbar palsy: Upper motor neurone lesion of CN9, 10 and 12.

Question 4

Distinguishing bulbar versus pseudobulbar clinically

Answer 4

LMN (bulbar) = nasal speech + tongue fasciculating + wasting

UMN (pseudobulbar) = hot potato speech + increased jaw jerk + spastic

Question 5

DDx for apparent MND

Answer 5

Cervical cord compression leading to myelopathy
Brainstem lesions
Polio: asymmetrical LMN paralysis
Mixed UMN and LMN signs:
"MAST"
MND
Ataxia, Friedrich's
SCDC (B12)
Taboparesis

Question 6

Investigations for MND

Answer 6

Brain/cord MRI to exclude structural cause (cervical cord compression or brainstem lesion)
EMG: fasciculation
Lumbar puncture to exclude inflammatory cause (e.g. multiple sclerosis)

Question 7

Diagnostic criteria for MND

Answer 7

Revised El Escorial Criteria (for ALS only)

Question 8

General management for MND

Answer 8

MDT

Discussion of end-of-life decisions, e.g. DNAR, advanced directive

Question 9

Medical management of MND

Answer 9

Riluzole is the only drug with proven benefit - prolongs lifespan by 3 months.
Symptomatic:
Drooling - hyoscine.
Muscle cramps - baclofen, quinine, diazepam.
Respiratory distress - opiates (palliative setting).
Depression - antidepressants.
Pain - analgesia.

Question 10

Prognosis in MND

Answer 10

Most die within 3 years due to bronchopneumonia and respiratory failure.
Worse prognosis: elderly, female, bulbar involvement.

Question 11

Types of MND

Answer 11

50% Amyotrophic Lateral Sclerosis
30% Primary Lateral Sclerosis
10% Progressive Bulbar Palsy
10% Progressive Muscular Atrophy

Question 12

Pathophysiology of Amyotrophic Lateral Sclerosis

Answer 12

Corticospinal tracts affected - UMN and LMN signs + fasciculation

Question 13

Pathophysiology of Primary Lateral Sclerosis

Answer 13

Loss of Betz cells in motor cortex - mainly UMN signs. Marked spastic leg weakness and pseudobulbar palsy. No cognitive decline.

Question 14

Pathophysiology of Progressive Bulbar Palsy

Answer 14

Only affects CN9-12 - bulbar palsy

Question 15

Pathophysiology of Progression Muscular Atrophy

Answer 15

Anterior horn cell lesion - LMN signs only. Distal to proximal. Better prognosis compared to ALS.