what are the symptoms of a UMN lesion?
- muscle weakness
- hyper-reflexia
- hypertonicity
- positive babinski sign
what is the name for the combination of hyper-reflexia and hypertonicity?
spastic paralysis
why does hyper-reflexia occur with UMN injury?
if damaged, higher cortical areas cannot provide inhibitory or modular control to the reflexes
what are the two types of hypertonic symptoms?
- spasticity
- rigidity
what is the difference between spasticity and rigidity?
spasticity is rate and force dependant (more resistance as limb is moved faster), no change in rigidity with rate or force
what is the clasp-knife phenomenon?
when moving a spastic joint, it will resist right up until the end of the ROM
what is decorticate posture?
extreme flexor posturing
what is decerebrate posturing?
extreme extensor posturing
what does decorticate posturing indicate?
the lesion is above the midbrain and involves the rubrospinal tract
what does decerebrate posturing indicate?
the lesion is below the midbrain and involves the vestibulospinal tract
what is a positive Babinski sign?
toe extension
what is characteristic of a hemiplegic gait?
the hip is hiked up or circumducted to keep walking while the leg stays extended
what are the causes of upper motor neuron lesions?
- injury to the motor cortex
- damage to internal capsule/cerebral peduncles
- spinal cord lesion or compression
- diseases attacking upper motor neurons
describe primary lateral sclerosis
- cause: unknown
- mechanism: degeneration of UMNs
- symptoms: UMN symptoms (i.e. spasticity, weakness)
- treatment: no cure
- speed: progresses slowly and non-fatal
describe amyotrophic lateral sclerosis
- cause: unknown, some genetic component
- mechanism: degeneration of UMNs and LMNs, glutamate build-up
- symptoms: UMN and LMN symptoms
- treatment: no cure, riluzole for glutamate
- speed: progresses rapidly and often fatal 2-4 years later
