Motor neurone disease

Question 1

What is motor neurone disease?

Answer 1

An umbrella term for a group of diseases that affect the upper and lower motor neurones while sparing other systems e.g. sensory

Degeneration and death of neurones in the brain, brain stem and spinal cord that control the muscles

UMN+LMN signs

Question 2

Common motor symptoms of MND related to site affected

Answer 2

Question 3

Pathophysiology of MND

Answer 3

Uncertain but various ideas:

1. Proteins aggregate in neuronal cell bodies and this causes death
2. Excessive glutamate signalling and excitotoxicity
3. Damage caused by oxidative stress

Question 4

Which symptoms would make a diagnosis of MND less likely?

Answer 4

Diplopia

Urinary/ bladder symptoms

Severe sensory symptoms/ pain

Vertigo

Tinnitus

Question 5

What is amyotrophic lateral sclerosis?

Answer 5

A [no] myo [muscle] trophic [nourishment] - the muscles receive no input from the nerves that have degenerated and they atrophy

Most common form of MND (65-85%)

• Combination of UMN and LMN signs

Median survival from start of symptoms = 3-5yrs

Question 6

What is progressive bulbar palsy?

Answer 6

Bulbar muscles = muscles of mouth and throat responsible for speech and swallowing

10% cases of MND

• 25% of these go on to develop widespread symptoms

Median survival from symptom onset: 6 months-3yrs

Question 7

Which cranial nerves are affected in progressive bulbar palsy?

Answer 7

CN IX, X and XII

Causes progressive difficulty with talking, eating and swallowing

• Increased risk of aspiration of saliva, often leading to pneumonia

Question 8

What is progressive muscle atrophy?

Answer 8

Type of MND - isolated LMN disorder

4% of cases

Presentation: LMN signs

Median survival 4.6yrs

Question 9

What is primary lateral sclerosis?

Answer 9

Isolated UMN lesion: motor cortex only

Rare form of MND

Presentation: UMN signs

10-20yr survival

Question 10

Which type of dementia can present with symptoms of MND?

Answer 10

Fronto-temporal dementia

Question 11

Risk factors of MND

Answer 11

Male

>40yrs

• FHx

Question 12

Typical presentation of MND

Answer 12

Insidious onset: stumbling, foot drop, slurred speech

Muscle stffness, paralysis, loss of coordination

Impaired speech and swallowing difficulty

Death: usually due to ventilatory failure ~3 years after symptoms start

Question 13

Investigations for MND

Answer 13

MND = clinical diagnosis

Bloods: CK raised as muscles atrophy

Electromyography: shows diffuse denervation of muscles in 2+ regions

MRI brain and spine: rule out other causes

Question 14

Management of MND

Answer 14

Muscle cramps: quinine

Exercise programmes: maintain ROM and prevent stiffness + discomfort

Saliva: advice, antimuscarinics (glycopyrrolate), botulin A

Nutrition: consider gastrostomy

Respiratory: opiods to relieve breathlessness, benzos if anxious, non-invasive ventilation

Coughing: manual assisted cough

Question 15

What is riluzole?

Answer 15

For patients with ALS form of MND

Antagonises glutamate and possibly reduces excitotoxicity that damages motor neurones

Prolongs survival by ~6 months

Question 16

When should end of life discussions happen with a diagnosis of MND?

Answer 16

At trigger points: diagnosis, change in resp, function, when ventilation/ grastrostomy needed

Bereavement support needed for family

Question 17

Main types of MND

Answer 17

ALS - most common

Primary lateral sclerosis - UMN only, rare, longest survival

Pogressive muscle atrophy: LMN only

Question 18

Typical MND presentation - describe a patient

Answer 18

60 year old male, right foot drop for 12 months, more proximal weakness over 2 months

Painful muscle twitches and cramps in same areas

Examination: lower extremity weakness, spasticity, atrophy of right foot intrinsic muscles, fasciculations, hyper-reflexia. Sensation preserved throughout