Disorders of Motility Flashcards
This is the isolated activity of an individual muscle fiver which occurs from a few days after interruption of a motor nerve. It is recorded in the EMG as a small, repetitive, short-duration potential.
Fibrillation
This is a visible twitch of a muscle fascicle resulting from contraction of one or several motor units which occurs when a motor neuron becomes diseased, with increased irritability, and then generate spontaneous impulses leading to sporadic discharge of the muscle fibers it controls in isolation from other units. The EMG shows this as large spontaneous muscle action potential.
Fasciculation
This is the simultaneous or sequential spontaneous contractions of multiple motor units, “rippling of muscle”
Myokimia
The Law of Reciprocal Innervation, Antagonists relax at the same rate that agonists contract
Sherrington Law
What are the principal neurotransmitters of the following:
(1) Neuromuscular junction
(2) descending corticospinal tract
(3) Renshaw cells, recurrent inhibition, interneurons that mediate reciprocal inhibition during reflexes
(4) Inhibitory neurotransmitter of interneurons in the posterior horn
(1) Neuromuscular junction - acetylcholine
(2) descending corticospinal tract- glutamate and aspartate
(3) Renshaw cells, recurrent inhibition, interneurons that mediate reciprocal inhibition during reflexes- glycine
(4) Inhibitory neurotransmitter of interneurons in the posterior horn- GABA
How fast does a muscle atrophy after denervation?
A denervated muscle may be reduced by 20-30% of its original bulk within 3-4 months after injury
To which brainstem nuclei does the corticobulbar tract have direct connections to?
The corticobulbar tract has direct connections to the trigeminal, facial, ambiguus, and hypoglossal nuclei
What is Broadbent’s Law?
It describes the pattern of central facial palsy
What is the bundle of fibers from the cortex destined for the facial nucleus which first goes down to the upper medulla before decussating and going back up to the pons called?
Pick’s bundle. It explains why some patients with upper medulla or lower pons lesions have central pattern of facial weakness.
What is usual frequency of clonus?
About 5-7 Hz. Constant by 1 Hz
Which corticospinal fibers cross more rostrally in the medullary pyramids?
Upper limb fibers
Differentiate the different forms of apraxia and their localization
Ideational apraxia- failure to conceive or formulate an action to command - sensory areas 5&7 in dominant parietal lobe, bilateral supplementary and premotor cortices
Ideomotor apraxia- cannot execute pllaned acute with either hand, even if he may remember how to do it- left parietal region
Limb-kinetic apraxia- ill defined clumsiness or maladroitness from inability to fluidly connect or isolate individual movements of the hand and arm
sympathetic apraxia- paralysis on one side obscures apraxia on that side, but there is also a breakdown of fine finger movements on the opposite side
oral-buccal-lingual-apraxia- unable to carry out facial movements on command- left supramarginal gyrus or left motor association cortex
dressing apraxia, constructional apraxia- specific apraxias from non-dominant parietal lobe
What entities can produce the “alien hand” phenomenon?
(1) ACA infarction involving the corpus callosum
(2) lesions of left supplementary motor area
(3) corticobasal ganglionic degeneration
(4) some cases of PCA strokes with sensory loss
What is utilization behavior? Where can it be localized?
Utilization behavior is when a patient obligatorily seizes and uses objects in the surrounding environment
It is associated with extensive bilateral frontal lobe damage
What tests can be used to differentiate psychogenic from true paralysis?
(1) Hoover sign - put hands under both heels, ask pt to push down; then put one hand on top of nonparalyzed leg, the other under the paralyzed leg and ask pt to raise nonparalyzed leg
(2) push knees or arms together; say you are testing the good side
(3) trunk thigh sign- ask pt to sit up with arms crossed at the chest. In true paralysis, Weak limb flexes when trying to sit up.
What are the input structures in the basal ganglia?
The striatum- the caudate nucleus and the putamen
What are the output structures of the basal ganglia?
The internal globus pallidus and the substantia nigra pars reticulata
What are the ansa lenticularis and fasciculus lenticularis? How are they different?
They are output tracts from the globus pallidus interna to the thalamus (they join the thalamic fasciculus)
The ansa lenticularis sweeps around the internal capsule
The fasciculus lenticularis passes through the internal capsule
Does the thalamus project back to the basal ganglia? How?
Yes.
The centromedian nucleus of the Intralaminar region projects back to the putamen, while the parafascicular nucleus projects to the caudate nucleus.
What are the neurotransmitters involved in the basal ganglia circuitry?
Dopamine (from substantia nigra pars compata)
Glutamate (excitatory projections from cortex to striatum, and from subthalamic nucleus)
GABA (inhibitory neurotransmitter of striatal, pallidal and substantia nigra pars reticulata neurons)
acetylcholine (golgi type 2 nonspiny striatal neurons)
substance P, enkephalin, cholecystokinin, somatostatin, neuropeptide Y
What are the different dopamine receptor types and where are they concentrated in the brain?
D1 and D2- striatum
D3- nucleus accumbens
D4- frontal cortex and certain limbic structures
D5- hippocampus
What is the principal location of the lesion in the ff. conditions:
(1) Parkinson’s disease
(2) Unilateral hemiballismus and hemichorea
(3) Chronic chorea of Huntington type
(4) Athetosis and Dystonia
(5) Palatal and facial myoclonus
(1) Parkinson’s disease- substantia nigra, contralateral
(2) Unilateral hemiballismus and hemichorea- contralateral subthalamic nucleus
(3) Chronic chorea of Huntington type- caudate nucleus and putamen
(4) Athetosis and Dystonia- contralateral striatum
(5) Palatal and facial myoclonus- ipsilateral central tegmental tract with denervation of inferior olivary nucleus and nucleus ambiguus
This is the variable resistance to passive movement where the patient appears unable to relax a group of muscles on request. When the limb muscles are passively stretched, pt appears to actively resist the movement.
Gegenhalten, Paratonia or Oppositional resistance
Give at least 10 conditions that can cause chorea
Inherited conditions such as Huntington’s disease, benign hereditary chorea, neuroacanthosis, dentatorubropallidoluysian atrophy, Wilson disease
Drug induced, such as in patients given neuroleptics like phenothiazines, haloperidol and metoclopromide; oral contraceptives, phenytoin, excess L-dopa and dopa agonist, cocaine
Systemic diseases such as thyrotoxicosis, polycythemia vera, hyperosmolar nonketotic hyperglycemia, toxoplasmosis in AIDS, hyponatremia, hypoglycemia
Hemichorea can be caused by stroke, tumor, vascular malformation
Differentiate chorea, athetosis, ballismus and dystonia
Chorea - involuntary, arrhythmic movements of a forcible, rapid, jerky type
Athetosis- inability to sustain the body part in one position; the maintained body posture is interrupted by relatively slow, sinuous, purposeless movements that have a tendency to flow into one another
Ballismus- uncontrollable, poorly patterned flinging movement of an entire limb
Dystonia- unnatural spasmodic movement of posture that puts the lime in a twisted posture
Give at least 10 conditions that can cause athetosis
Huntington's disease Double athetosis Cerebral palsy (anoxia) Kernicterus Hepatic encephalopathy Chronic intoxication with phenothiazines or haloperidol Wilson's disease Leigh disease and other mitochondrial disorders Nieman-Pick type C Kufs Disease neuroacanthocytosis Ataxia telangectasia Excessive L-dopa AIDS AEDs Vascular lesion of lenticular nucleus or thalamus
Give at least 3 causes of ballismus
When unilateral, from an acute lesion of or near the contralateral subthalamic nucleus
Bilateral may be from metabolic disturbances such as nonketotic hyperosmolar coma, paraneoplastic process
What medication can be given to suppress ballismus?
Haloperidol or phenothiazine may suppress violent movement
