Amyotrophic lateral sclerosis

Question 1

Definition

Answer 1

A type of motor neuron disease
– relentless and unexplained destruction of upper motor neurons and the anterior horn cells in the brain and spinal cord

ALS specific:
– relentless and unexplained destruction of the upper motor neurons and anterior horn cells in the spinal cord, brainstem and corticospinal tract

Question 2

Aetiology

Answer 2

ALS is inherited in 5-10% of people
– for the rest the cause is unknown

Most theories centre on a complex interaction between genetic and environmental factors

Question 3

Epidemiology

Answer 3

Most cases are sporadic

However, 5% are familial

Question 4

Pathophysiology

Answer 4

Characterised by the atrophy and degeneration of the motor neurons

There may be loss of motor neurons in the ventral spinal horns, most brainstem motor nuclei and motor cortex

Question 5

Risk factors

Answer 5

Hereditary

Age- risk increases with age, and is most common between the ages of 40 and mid 60’s

Sex- before the age of 65, men more than women

Genetics

Question 6

Clinical presentation

Answer 6

Simultaneous involvement UMN and LMN, usually in one limb and gradually spreading to other limbs and trunk muscles
– ALS often starts in the hands, feet or limbs, and then spreads
—- as the disease advances and nerve cells are destroyed more, your muscles get weaker. eventually affecting chewing, swallowing, speaking and breathing

– progressive focal muscle weakness and wasting
—- with muscle fasciculation’s due to spontaneous firing of abnormally large motor units formed by surviving axons

Cramps are common but a non specific symptom

Brisk reflexes
Extensor plantar responses and spasticity

UMN:
– hypers

LMN:
– hypos

Sometimes:
– an assymetric spastic paraparesis is the presenting feature with lower motor neurone features developing months later

Relentless progression of signs and symptoms over months will allow a diagnosis.

Question 7

Investigations

Answer 7

Cranial nerve exam

Peripheral nerve examination

Diagnosis is entirely dependent upon the UMN and LMN findings in 3 key ares of the 4 of the body

Diagnosis may not be definitive straight away and may be a period of watchful waiting

Question 8

Treatment

Answer 8

Treatment cant reverse the damage, but can slow the progression of symptoms down, prevent complications, and make you more comfortable and independent

Medications:
– Riluzole- increases life expectancy by 3 to 6 months

– side effects:
—- dizziness, GI conditions

Therapies:
– physical, breathing and occupational
– speech therapy
– nutritional support
– psychological and social support