UPPER & LOWER MOTOR NEURON LESIONS

Where does an upper motor neuron lesion occur?

Anywhere in the corticospinal tract, from primary motor cortex to synapses with anterior horn motor neurons

Fasciculations, are a characteristic of LMNL, what are they?

Contractions of groups of muscle fibres, can be seen in skeletal muscles

Where does a lower motor neuron lesion occur?

In the anterior ventral horn, and in the motor neurone cell bodies and axons projecting to the innervated muscles

Speech and swallowing characteristics of UMNL - Unilateral UMN lesion?

Unilateral UMN lesion: Less severe, may lead to spastic signs of contralateral side of lesion, tongue muscles receive intermediate contralateral UMN innervation, jaw, upper face, pharynx, larynx

Causes of Lower motor neuron lesions?

Brainstem stroke affecting the LMN nuclei, lesion to the spinal nerve, cranial nerve damage, lesions directly in muscles

Test for hypertonicity?

Examiner tried to displace arm and judges resistant in passive motion

Fibrillations are a characteristic of LMNL, what are they?

Fibrillations are fine twitches of single muscle fibres, generally cannot be seen on clinical exam, usually detected by EMG

Speech and swallowing characteristics of LMNL?

Flaccid dysarthria: possibly imprecise articulation, hyper nasality, voice difficulties. Dysphagia: Cant raise palate

Hypertonicity is a characteristic of UMNL, what is it?

Hypertonicity is finding it hard to stretch limbs

Plantar response is a characteristic of UMNL, what is it?

Plantar response is when the toes fan upward

Speech and swallowing characteristics of UMN- Bilateral UMN lesion>

Spastic dysarthria: Imprecise consonant production, low pitch, slow speaking rate, harsh voice, dysphagia

What are the causes of UMNL?

Stroke, TBI, traumas, degenerative disease

Facial muscle, UMNL characteristic?

Unilateral lesion: Only lower facial weakness of the contralateral side of the face