Motor neuron disease- Neurology/IM

Question 1

Definition of motor neuron disease

Answer 1

A degenerative disease of a gradual onset and progressive course, affecting the motor system only (systemic disease). It may affect UMN or LMN, or both.

Question 2

Describe UMN, LMN and Combined affection in motor neuron disease

Answer 2

UMN AFFECTION:
a) In the spinal cord: “Primary Lateral Sclerosis”
1. Spastic paraplegia if the lesion is below the cervical region, or
2. Spastic quadriplegia if the lesion is at the cervical region.
b) In the brain stem or the cerebral hemisphere: “Pseudobulbar palsy”

LMN AFFECTION:
The disease has a tendency to affect the AHCs in the spinal cord or the cranial nerve nuclei in the brain stem.
a) In the AHCs:” Progressive muscular atrophy”
▪ The AHCs, mostly affected, resulting in weakness with signs of LMNL i.e. wasting, hypotonia. Hyporeflexia and fasciculations.
b) Cranial nerve nuclei: “True bulbar palsy” “Progressive bulbar palsy”
▪ 20% cases. - More common in elderly women.

Combined UMN and LMN affection: “Amyotrophic lateral sclerosis”(ALS)
●Most common MND (70% of cases).
●There are combined signs and symptoms of LMNL and UMNL:
a) In the upper limbs there will be weakness, associated with wasting and fasciculation (LMNL) as well as hypertonia and hyperreflexia (UMNL). This is known as Tonic Atrophy.
b)In the lower limbs there will be weakness with signs of UMNL (spastic Paraparesis). There may be minimal fasciculations if the lumbar AHCs are affected.

Question 3

differences between true and pseudo bulbar palsy

Answer 3

Pseudo bulbar palsy
1) UMNL.
2) Associated with quadriplegia.
3) Exaggerated palatal and pharyngeal reflexes.
4) The jaw reflex may be exaggerated.
5) Emotional lability may be present.
6) Tongue: no wasting or fasciculations.

True bulbar palsy
1) LMNL.
2) NO quadriplegia.
3) Lost palatal and pharyngeal reflexes.
4) Absent jaw reflex.
5) No emotional lability.
6) Tongue: small, flaccid & shows fasciculations.

Question 4

Outline the treatment of MND

Answer 4

1) Riluzole (Rilutek)
2) Edaravone (Radicava)
3)Physiotherapy
4) Symptomatic treatment.
●Spasticity: muscle relaxants.
●Emotional lability (pseudobulbar affect): combination of dextromethorphan and quinidine.
●Sialorrhea: Anticholinergics and sympathomimetic.
●Thickened secretions: Mucolytic.
●Depression: SSRIs.
●Pain: NSAIDs, tramadol, ketorolac, morphine or transdermal fentanyl.