Movement disorders Flashcards
What two parts of the brain is thought to be responsible for movement?
- Basal Ganglia - function is not fully known - thought to be linked to initiation and execution of movements
- Thalamus - transmits signals from the cerebral cortex to the spinal cord
MOA of dopamine
- NT involved in interneuronal communication
- Inhibits release of Ach at nerve terminal
- Helps to make smooth motor movements and motor control
inhibitory neurotransmitter that relaxes muscle and allows motor control
GABA
Gamma-aminobutyric acid
a NT found at neuromuscular junction and in the autonomic ganglia. Increased neuronal excitability in the periphery and functions as as neuromodulator in the CNS
Acetylcholine
An involuntary, rhythmic, and oscillatory movement of a body part
Tremor
Can affect hands, arms, head, face, voice, trunk, and legs
how are tremors caused?
either alternating or synchronous contractions of antagonistic muscles
Neural dysfunction or lesions that result from injury, ischemia, metabolic abnormalities, or a neurodegenerative disorder.
MC movement disorder
tremor
how are tremors categorized?
resting or action
this tremor occurs in a body part that is fully supported, relaxed, and not voluntarily activated
resting tremor
Occurs in an attempt to maintain a specific posture or position against the force of gravity
what type of tremor?
Action
Postural
Occurs during any voluntary movement
what type of tremor
action kinetic
Occurs during a muscle contraction against a rigid, stationary object
what type of tremor
action isometric
what are the 3 subcategories of action kinetic tremor?
- Simple Kinetic: during voluntary movements that are not target directed (e.g. pronation-supination)
- Intentional: worsens as the body part approaches its target (e.g. eating)
- Task-specific: occurs during a specific task (e.g. writing)
descriptors of tremors
- Frequency Hz / sec
- < 4 (slow)
- 4-8
- 8-12
- >12 (fast) - Amplitude - ROM
- low (smaller movement)
- high (larger movement)
A very low-amplitude, high-frequency (8 to 12 Hz) physiologic action tremor in the upper limbs.
MC type of action tremor
Enhanced physiologic tremor
Enhanced physiologic tremor is present only when there is ?
sympathetic activation
- stress, anxiety, excitement, muscle fatigue
- F, hypoglycemia, thyrotoxicosis, pheochromocytoma
- alc or opioid withdrawal
- meds, drugs, and substances
management for enhanced physiologic tremor?
- Tremor resolves when precipitating factor is removed
- Treat/remove underlying causes
Most common adult onset “neurological” movement disorder
essential tremor (ET)
pathophys of ET
not fully understood - altered cellular activity in ventral intermediate (VIM) nucleus of thalamus
epidemiology of ET
- Incidence increases with age
- Mean age - 35-45 years
- Usually manifests by 65 y/o
- FHx present 30-70 % of pts
presentation of ET
- MC bilaterally affects hands and arms
- > the head, voice, face and trunk - Both postural & kinetic properties
- arms postured against gravity or during goal-directed movements (e.g. drinking from a glass or F-N testing)
- Resolves w/ rest or if extremity is fully supported - trouble w/ fine motor activity - eating, drinking, pouring, writing, typing, texting, and applying makeup
- Exacerbated by emotion, hunger, fatigue, temperature extremes - NOT by caffeine
- Improves w/ alcohol (small)
- Progressive over time
- F-N testing - mild or absent tremor until after the target is reached
You suspect an essential tremor in your patient but they have more of a isolated head or voice tremor, what is your next step?
Find other cause! - Dystonic head tremor, Spasmodic dysphonia
isolated head or voice tremor excludes ET
How to DDX of ET
- Enhanced physiologic tremor - worsened by caffeine, resolves when precipitating factor is removed
- Parkinson disease - at onset unilateral resting tremor, rigidity, bradykinesia
- Dystonic head tremor - isolated head tremor
- Spasmodic dysphonia - isolated voice tremor
- Cerebellar tremor - intention related qualities and other signs cerebellar dysfunction (ataxia)
- Wilson’s disease - asymmetric tremor, other neurologic sx (dysarthria, dystonia, chorea etc.)
How to DX ET?
made clinically based upon hx and PE
Labs for ET
USED TO R/O SECONDARY CAUSES OF TREMOR
CMP - electrolyte imbalance
Thyroid function tests - hyperthyroidism
Serum ceruloplasmin - Wilson disease¹
Diagnostic Criteria for ET
International Parkinson and Movement Disorder Society (IPMDS) task force
- Isolated tremor consisting of bilateral upper limb action (kinetic and postural) tremor, w/o other motor abnormalities
- At least 3 years in duration
- w/ or w/o tremor in other locations
- Absence of other neurologic signs (dystonia, ataxia, or parkinsonism)
management for ET
Tx recommended for intermittent /persistent disability d/t tremor
Intermittent:
- 1st line - Propranolol (30 min prior to activity); (Alt) Primidone qhs
- 2nd line - BZD - alprazolam (Xanax), clonazepam (Klonopin) - reduces anxiety that worsens ET - not recommended for chronic use
Continuous
- 1st line - propranolol BID; primidone; Combo
- 2nd line - Anticonvulsants: gabapentin (Neurontin), pregabalin (Lyrica), topiramate (Topamax)
- 2nd line - refer to neurologist
- Botox into affected muscle - reserved for head tremors unresponsive to pharm
- Surgical intervention: Deep brain stimulation vs thalamotomy
indication for surgical therapy for ET
disabling tremor with failure of 2 oral regimens
CI for surgery in ET
dementia or significant cognitive impairment¹, uncontrolled anxiety/depression
What is VIM nucleus deep brain stimulation
Implantation of an electrode into the VIM nucleus connected to a pulse generator implanted in the chest wall below the clavicle which delivers unilateral high-frequency electrical stimulation when activated
For ET
what is MRI-guided focused ultrasound thalamotomy
Uses high-energy US beams to create a permanent lesion in the VIM nucleus of the thalamus - performed on the opposite side of the most severely affected arm
for ET
A target-directed coarse tremor that worsens when closest to the terminal target
Intention (kinetic) tremor
Frequency - 3 to 4 Hz
How would an Intention (kinetic) tremor present on a finger-to-nose test?
Abnormal finger-to-nose testing
* No tremor at start but become more severe as directed movement advances to target
* may continue for several beats after the target has been reached