Hypokinesia
Encyclopedia
Hypokinesia refers to decreased bodily movement. It is associated with basal ganglia
diseases (such as Parkinson's disease
), mental health disorders and prolonged inactivity due to illness, amongst other diseases.
Hypokinesia describes a spectrum of disorders:
Basal ganglia
The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...
diseases (such as Parkinson's disease
Parkinson's disease
Parkinson's disease is a degenerative disorder of the central nervous system...
), mental health disorders and prolonged inactivity due to illness, amongst other diseases.
Hypokinesia describes a spectrum of disorders:
- Akinesia ( a-Privative aIn Ancient Greek grammar, privative a is the prefix a- that expresses negation or absence . It is derived from a Proto-Indo-European syllabic nasal *, the zero ablaut grade of the negation *ne, i.e. /n/ used as a vowel...
, "without", kinēsis, "motion") is the inability to initiate movement due to difficulty selecting and/or activating motor programs in the central nervous system. Common in severe cases of Parkinson's diseaseParkinson's diseaseParkinson's disease is a degenerative disorder of the central nervous system...
, akinesia is a result of severely diminished dopamineDopamineDopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
rgic cell activity in the direct pathway of movementDirect pathway of movementThe direct pathway of movement is a neuronal circuit within the central nervous system through the basal ganglia which facilitates the initiation and execution of voluntary movement...
. - Bradykinesia ( bradys, "slow", kinēsis, "motion") is characterized by slowness of movement and has been linked to Parkinson's disease and other disorders of the basal ganglia. Rather than being a slowness in initiation (akinesia), bradykinesia describes a slowness in the execution of movement. It is one of the 3 key symptoms of parkinsonism, which are bradykinesia, tremor and rigidity. Bradykinesia is also the cause of what is normally referred to as "stone face" (expressionless face) among those with Parkinson's.
- Freezing is characterized by an inability to move muscles in any desired direction.
- Rigidity is characterized by an increase in muscle tone causing resistance to externally imposed joint movements. It does not depend on imposed speed and can be elicited at very low speeds of passive movement. It is felt in both agonist and antagonist muscles and in movements in both directions. 'Cogwheel' rigidity and 'leadpipe' rigidity are two types identified with Parkinson's disease. 'Leadpipe' rigidity results when an increase in muscle tone causes a sustained resistance to passive movement throughout the whole range of motion, with no fluctuations.'Cogwheel' rigidity is a combination of leadpipe rigidity and tremor which presents as a jerky resistance to passive movement as muscles tense and relax. SpasticitySpasticitySpasticity is a feature of altered skeletal muscle performance in muscle tone involving hypertonia, which is also referred to as an unusual "tightness" of muscles...
is a special form of rigidity that is present only at the start of passive movement. It is rate dependent and only elicited upon a high speed movement. These various forms of rigidity can be seen in different forms of movement disorders, such as Parkinson's diseaseParkinson's diseaseParkinson's disease is a degenerative disorder of the central nervous system...
. - Postural instability is the loss of ability to maintain an upright posture.