Pathologies Flashcards
What is the definition of a stroke?
A rapidly developed clinical sign of localised effect on cerebral function of vascular origin and of more than 24 hours duration
What are the 2 main types of stroke?
Ischaemic - a blood clot of an artery
Hemorragic - bleeding on the surface of the brain
Where does a stroke usually occur?
At the middle cerebral artery
What is a Transient Ischaemic Attack (TIA)?
A mini-stroke of less than 24hours duration
Define an atheroma
An accumulation of fatty deposits in an artery resulting in the formation of a plaque which causes degeneration of the arterial walls and forms a blood clot. .
Define an embolism
A condition where blood flow is stopped by a clot/air bubble
Define hemiplegia
Paralysis of one side of the brain which affects the contralateral side.
Define hemonymous hemianopia
The loss of the field of view on the same side in both eyes down a vertical axis.
What are the clinical signs (gait changes) seen in a stroke? (Motor, sensory)
- Increased flexor tone in the upper limb shown by adduction of the shoulder, elbow flexion and wrist flexion/in a fist.
- Increased extensor tone in the lower limb and internal rotation and supination of the foot.
- Decreased motor control of the hip, knee and ankle flexors. This combined with the increased extensor tone results in a functional leg length discrepancy, causing compromising movements such as circumduction of the hip and hip hitching.
- Decreased stability and balance of the affected side shown by a quick transition in mid stance due to lack of trust of the affected limb
- Decreased sensation of the affected limb, sometimes causing neglect.
- Swallowing difficulties
- Decreased heel strike and propulsion in gait.
Define muscle tone. What is the role of the gamma motor neurone?
The internal state of tension of a muscle. The gamma motor neurone ‘resets’ the intrafusal fibre and sets its sensitivity to stretch so that it remains taut after it has been stretched so that it can continue to send sensory sensation to the spinal cord.
What descending influences affect muscle tone?
Reticular formation - medial and lateral reticulospinal tracts
Vestibular nuclei - medial and lateral vestibulospinal tracts
Vestibulocerebellum
Red nucleus - rubrospinal tracts
Gravity, emotional state
What is the difference between hyper and hypotonicity?
Hypertonicity is more than normal muscle tone, hypotonicity is less than normal muscle tone.
What is Parkinson’s disease? What is it caused by?
A degenerative disorder of the CNS due decreased production of dompamine due to death of dopamine producing cells in the substantia nigra. Abnormal protein clusters called Lewy bodies form here instead. . This causes increased inhibition of the thalamus by the basal ganglia, therefore activity in the primary motor cortex is decreased = hypokinetic disorders.
What is the role of the basal ganglia?
Initiate/terminate movement
Prevents unwanted movement by acting as a modulator and ‘brake’ to the excitatory action of the thalamus on the PMC.
Role in the motor planning stages e.g. supplementary and pre- motor cortices.
What are the clinical signs shown in a Parkinson’s gait?
- Kyphotic posture - bent over, moving the centre of mass towards the edge of the base of support causing postural instability and balance issues.
- Increased rigidity of the trunk results in decreased arm swing. Rigidity is either cog wheel or lead pipe.
- Bradykinesia (slowness of movement) - results in a shuffling gait - this causes decreased step and stride length, decreased heel strike and decreased propulsion on toe off.
- Patients also have festinations and freezing, difficulty initiating movements and turning.
- Resting tremor
- Fine motor impairment e.g. problems zipping, doing buttons.
