Exam I Flashcards
Hierarchical processing
higher level of CNS are concerned with abstract processing of information and lower levels bring in/send information
Parallel processing
the same signal might reach different brain structures simultaneously for processing (divergent), but different purposes.
Spinal cord connections
Hierarchically ‘lowest level employees’ – responding to sensory inputs and following ‘orders’ from action systems
Involved in initial signal reception and final execution of voluntary/involuntary movements (final common pathway)
Basic/simple signal processing – spinal reflexes
Brain Stem connections
‘Middle management’ - contain important control centers (sensory and motor) for postural control and locomotion, Receives inputs from head/neck, vestibular and visual systems, sends somewhat processed signals to sensory/perceptual centers, contain motor nuclei for descending pathways to neck/face/eyes, and extra pyramidal pathways
Cerebellar connections
‘back-channel employee’ needed for comparing and calibrating movements, contains feedback and feedforward mechanisms. it has Indirect influence on motor outputs to generate smooth coordinated movements, important center for coordination and postural control during movements.
Thalamus connections
The ‘doorkeeper to the boardroom’
Acts as a junction, a relay center for signal processing
Basal Ganglia connections
Involved in higher order motor planning for coordinated movements
Receives inputs from many areas of cerebral cortex
Sends output back to motor cortex via thalamus
Cerebral Cortex connections
Highest executive level of motor control hierarchy, Has direct control on voluntary movements by activating/controlling motor neurons via corticospinal/corticobrainstem pathways
Interacts with other high level association cortical areas (premotor/SMA) to form motor plan/strategy
cross-modal processing
Information from muscle spindles, joints receptors, cutaneous receptors, etc., are integrated to give accurate information about movements in a limb
Primary motor cortex connections
Primary motor cortex have one-to-one connection (somatotopy) to the level of single motor neuron in spinal cord.
However, convergent and divergent parallel pathways are possible– one cortical site can be connect to a bunch of motor neurons (hence muscles) and one muscle can also potentially be connected to many neurons in a cortical site.
Important for recovery after injuries
Supplemental Motor Area
controls internally generated movements, also controls learned motor programs, but can transfer those programs to primary motor cortex after extensive training, also involved in planning complex motor programs
Premotor (PM) area
controls movements activated by external stimuli, like visual cues, e.g., ‘go’ when signal changes to green
Necrosis
severe injury - cellular swelling (osmosis), fragmentation of structure and cell disintegration, inflammatory response
Apoptosis
programmed cell death, no inflammatory reaction
Excitotoxicity
when neurotransmitters rise above normal levels – opens ion channels leads to excessive entry of Ca2+ ions – triggers all kinds of harmful cellular pathways – cell death
anesthesia
If all sensory modalities lost/absent
hypoesthesia
if partial loss of somatosensory
hyperesthesia
if somatosensory is hypersensitive
Parasthesia
unpleasant sensations like burning, tingling, pricking, numbness with/without sensory stimulus
Allodynia
painful sensation to a normal stimulus that should not be painful
Hyperalgesia
increased painful sensations to normally painful stimulus
Peripheral vestibular disorders
Nerve problems - vestibular neuritis (infection of nerve), perilymph fistula, Meniere’s disease
Canal problems - BPPV
Central vestibular disorders
Stroke in brainstem/cerebellum
Cerebellar degeneration
Arnold-Chiari malformation (cerebellum is coming out of foramen magnum
Nystagmus from peripheral lesions
Direction-fixed beating
Follows Alexander’s and Ewald’s laws
Beating increases as eyes are moved towards the fast phase
Beating occurs in the plane of impaired canals
Able to fixate with gaze stabilization
Habituates/compensates rapidly with time
Good outcomes with vestibular rehab
Examples of disorders – vestibular neuritis, BPPV
Nystagmus from central lesions
Pure vertical or pure torsional or direction-changing beating depending on gaze
Does not follow Alexander’s law
Unable to fixate with gaze stabilization
Takes longer to habituate/compensate
Worse (than peripheral) outcomes
Examples of disorders – Stroke in brainstem/cerebellum, medications
Patterns of motor deficits for UMN disorders
Paresis/paralysis
Abnormal tone - spasticity
Abnormal reflexes
Loss of fractionated movements/abnormal synergies
No atrophy
Abnormal co-contractions - CP
Patterns of motor deficits for LMN disorders
Paresis/paralysis
Decrease in muscle tone - flaccidity
Decrease in reflex activity
Neurogenic atrophy – due to lack of trophic support to muscles
Tone
resistance to passive stretch
Hypertonia results from…
results from increased baseline muscle sensitivity to stretch through mechanisms like loss of descending inhibitory control on motor neurons, loss of presynaptic inhibition, denervation hypersensitivity, etc.
Hypotonia results from…
results from decreased lower motor neuronal (LMN) activity on muscles due, damage to peripheral nerve, or due to other subcortical lesions, in cerebellum, or from developmental delays
Spastic paralysis caused by UMN lesions
velocity-dependent hypertonia
Flaccid paralysis can be caused by…
LMN lesions (due to decreased neuronal activity on muscles), or immediately after UMN lesions (as a result of shock).
Rigidity
caused by extrapyramidal lesions - velocity-independent hypertonia
UMN - Signs of spastic paralysis
weakness, increased tone, increased reflexes, spastic patterns/synergies (eg, flexors for UE and extensors for LE in stroke)
LMN - Signs of flaccid paralysis
weakness, decreased tone, decreased reflexes, muscle atrophy, fasciculations and fibrillations, eg, polio, peripheral nerve injuries
spastic pattern
Abnormal stereotypical patterns of movements that cannot be adapted – muscles are tightly linked, typically associated with stroke
spastic synergies
Typical flexion and extension synergies of UE and LE, person perform voluntary movements in these patterns, typically associated with stroke
Movement problems associated with cerebellum
delayed timing, dysmetria (errors in force, ROM, direction), dyesynergia (incorrect sequence of muscle activation), dysdiadokokinesia (difficulty with RAM), Intention tremors (involuntary rhythmic oscillations), and rebound phenomenon (inability to terminate movements), all of these make up ataxic gait, more include dysarthria and asthenia
Movement problems associated with basal ganglia
hypokinesias, hyperkinesias such as chorea (twitching, jerking movements), athetosis (writhing, twisting movements), Ballismus (violent, flinging movements), resting tremors
Resting tremor
When body is supported and relaxed, hallmark of PD
Intention Tremor
Target related movements
Hallmark of cerebellar dysfunction
Ataxic gait
cerebellar lesions – wide-based staggering gait, excessive trunk movements, arms wide out, lack of arm swing, LOBs towards ipsilateral side, difficulty in maintaining a line.
Parkinsons gait
short shuffling gait with festinations, freezing, difficulty turning, tremor in arms at times
Scissoring gait
in spastic CP due to adductor spasticity
Hemiplegic gait
circumducting or hip hiking due to LE extensor spastic synergies, arm in flexor synergy
Neuropathic gait
high steppage gait due to DF weakness and diminished sensation from feet, eg, diabetic neuropathy
Right hemisphere deficits
Spatial deficits – hemineglect, tactile extinction (more common with right-side lesions)
Non-spatial deficits – reduced levels of arousal, attention, orientation to stimuli, emotional disturbances
Left hemisphere deficits
Problems with reading, writing and understanding of speech
Apraxia
inability to perform skilled movements in spite of intact sensory & motor systems.
Agnosia
lesions in sensory cortices for seeing/hearing/feeling – could be one modality, can compensate using remaining modalities
Persistent vegetative state (PVS)
if the link from cortex to brainstem is destroyed, eyes may open, have sleep-wake cycles and show random movements, but still unconscious and unresponsive to any stimulus
Locked-in syndrome
damage to pons, opposite of PVS, cognitively fully aware w/o any mental deficits, but cannot move any body parts, except eyes and blink.
Cerebral palsy
Non-progressive lesion in the brain occurring prior to 2 years of age. Can have wide spread consequences, Caused by damage to or abnormalities in the developing brain areas that disrupt movement control, posture and balance.
Classification of cerebral palsy
Spastic CP (Pyramidal/corticospinal pathways), Dyskinetic CP (basal ganglia), Ataxic CP (cerebellum)
Dyskinetic Cerebral Palsy
Chorea and/or athetoid-type involuntary movement problems
Dyskinesia during voluntary movement
Lack midrange motor control the most, use end range motions to accomplish tasks
Lack postural control, trunk muscle co-activation
Cerebral Palsy etiology
2nd most common neurologic impairment affecting children after ASD, Exact cause/time period may be unknown, but happens due to damage to the motor control systems of the brain sometime during prenatal, perinatal or postnatal periods, often difficult to pinpoint the period of damage, low birth weight
Cerebral palsy pathology
No consistent pathology
Various types of pathophysiological reasons
Mechanical trauma, metabolic problems, hypoxia, hemorrhage (injury from pressure), congenital malformations
Cerebral palsy clinical manifestations
Righting reactions, protective reactions, equilibrium reactions, Persistence of primitive developmental righting reflexes – ATNR, STNR, TLR, motor control problems, spaticity in adductors and iliopsoas, weakness, oral motor problems, contractures, sensory, respiratory, GI impairments
Righting reactions
used to orient head in space and align head and body
Used for developing head control and turning head/body
Integrated in 5yrs, when child starts to stand
Protective reactions
Downward LE, forward UE, sideways, backward, stepping
Persists
Equilibrium reactions
Allows body to maintain equilibrium by keeping COG over BOS during slow movements
Last to develop
Persists
Prognosis of cerebral palsy
Most children with mild to moderate CP have normal life span, with increased mortality risks before age 4 and then after 50 years due to respiratory/CV complications
Ambulation potential can be predicted based on achievement of milestones
Monoplegic ambulation potential
100%
Hemiplegic ambulation potential
100%
ataxia ambulation potential
100%
Diplegia ambulation potential
60%-90%
Spastic quadriplegia ambulation potential
0%-70%
Sits independently by age 2 ambulation potential
Good
Sits independently by age 3-4 ambulation potential
50% community ambulation
Presence of primitive reflexes beyond age 2 ambulation potential
poor
Absence of postural reactions beyond age 2 ambulation potential
poor
independently crawled symmetrically or reciprocally by age 2.5 ambulation potential
Good
Down syndrome
Also known as Trisomy 21, characterized by muscle hypotonia, cognitive delay, delayed development of gross motor skills, dysmorphic facial features and other distinctive physical abnormalities, rises sharply with increasing maternal age
Down syndrome etiology
No known cause is yet known
Down syndrome pathogenesis
Chromosomal abnormality
3 copies of chromosome 21 instead of a pair which results in a 47 chromosomes instead of 46
Extra chromosome can occur due to faulty miosis of ovum, Gene for free radical defense in chromosome 21, over expression of neurotrophic factors that are coded in chromosome 21, early onset of alziemers disease
Down syndrome clinical manifestations
muscle hypotonia and joint hyper extensibility, delayed acquisition of gross motor skills, sensory impairment, obesity, diabetes, also prone to ear and respiratory infections, decreased immune function
Down syndrome precautions
Activities resulting in increased forces on cervical spine may contraindicated, Lower oral motor tone can interfere with feeding, Need to educate parents. Child may need frequent feedings, clearing mucus from nose before feeds, changing child’s position frequently, postural drainage and percussion as necessary
Neural tube defects
Congenital spinal canal deformities resulting from failure of neural tube closure during development
3 types of NTDs
Spina Bifida Occulta
Meningocele
Myelomeningcele
4 reasons of failure to NT to close
Abnormalities in hyaluronic acid matrix
Abnormal overgrowth at the caudal end stopping the closure
Abnormal production of surface ectoderm glycoproteins, that act as glue to hold the cells together during closure.
Rupture of neural tube after its closure due to CSF pressure
Spina Bifida Occulta clinical manifestations
-Does not protrude visibly
-Depression/dimple on skin
-Tuft of hair present
-Soft fatty deposits underlying the skin
-Does not cause any neurologic dysfunction
-Occasional bladder/bowel disturbances and foot weakness
Meningocele clinical manifestations
Like Occulta, rarely causes any neurologic deficits
Myelomeningocele clinical manifestations
permanent neurologic impairment, flaccid (LMN type) paralysis, delayed postural reactions, absence of deep tendon reflexes, sensory impairments, msk deformities
Hydrocephalus
increased CSF pressure due to blockage in brain or after surgical closure of myelomeningocele.
Hydrocephalus signs/symptoms
Signs/symptoms include bulging soft spot (fontanel) on top of child’s head, enlargement of head, large prominent veins on scalp, setting sun sign (always looking down), seizures, vomiting, nausea, irritability, sleepiness
Arnold-Chiari type I
cerebellar tonsils extend down through foramen magnum
Arnold-Chiari type II
both cerebellum and brain stem extend down through foramen magnum
Arnold-Chiari type I or Type II malformations signs/symptoms
weakness, vertigo, ataxia, diplopia, pain. Some people are asymptomatic
Can also cause hydrocephalus
Tethered cord syndrome
Another common comorbidity following surgical closure of myelomeningocele
Spinal cord becomes ‘tethered’ or bound down resulting in progressive neurologic impairments like weakness, pain and incontinence
Bladder and bowel incontinence with myelomenigocele
Always present with myelomeningocele, either small spastic bladder (urge incontinence) or large flaccid bladder (overflow incontinence = infections), can have dyssynergistic bladder
Syringomyelia
Fluid-filled cavity or ‘syrinx’ present within spinal cord or brain stem – sleep apnea, choking, may require mechanical ventilation and can be fatal. Also cranial nerve involvement.
NTD prognosis
Early aggressive care has improved overall prognosis, Poorest prognosis in cases of total paralysis below lesion, kyphoscoliosis, hydrocephalus, progressive loss of renal function, If child is able to ambulate or use w/c outdoors by age 7, then good prognosis for functional mobility. If it does not happen by 7-9 years, then functional ambulation might not occur.
NTD implications for therapist
Pressure in sac must be avoided, prone positioning is optimal, sidelying is good for feeding or changing, with hydrocephalus, careful handling needed, avoid pressure and stretch to shunt, avoid head down positions, skin care, passive ROM and stretching
Muscular Dystrophies
Largest and the most common group of inherited progressive neuromuscular disorders. Typically symmetric progressive muscle wasting with increasing deformities and disabilities
Duchenne MD and Becker MD etiology
DMD most common and is x-linked recessive disorders. Males are predominantly affected with females being mostly carriers. Signs/symptoms are apparent by 2-4 years, rapidly progress, death in 20s.
BMD is slowly progressive, lifespan till adulthood, also x-linked, males mostly affected
Limb Girdle type MD etiology
Autosomal genetic inheritance, many subtypes, Onset in late childhood to early adolescence, Slowly progressive and milder presentation
Congenital MD etiology
Onset of symptoms at birth or shortly afterwards, Mostly autosomal recessively inherited, Severity and rate of progression varies, some die in first years, other can live longer and achieve ambulation
Facio-Scapulo-Humeral MD etiology
autosomal dominant disorder, Son or daughter of affected person has 50% chance of inheriting the defective gene (males>females). Age of onset is early adolescence, slowly progressive, lifespan varies
Myotonic Dystrophy etiology
autosomal dominant, often in isolated geographic locations due to local founders effect. subsequent generation shows more severe clinical presentation.
Duchenne and Becker MD pathogenesis
caused by mutations of the dystrophin gene Xp21. Muscle is replaced by fatty, connective tissue and contractures develop.
Dystrophin
part of the Dystrophin glycoprotein transmembrane complex, dystrophin links muscle membrane(sarcolemma) to the contractile proteins (actin/myosin). lack of normal dystrophin leads to disruption of sarcolemma during contraction-relaxation cycles, allows uncontrolled influx of Ca2+, which triggers destruction of the muscle cell.
DMD versus BMD
-Males with undetectable levels of dystrophin have DMD
-Males with abnormal sized or lower levels of dystrophin have BMD
-Those who lose ambulation prior to 13 years age fall in DMD, those who walk past 16 years fall in BMD group, while those who walk past age 12 and lose that ability by 15 is defined as ‘intermediate MD’.
Limb Girdle MD pathogenesis
Type 1 inherited dominantly and type 2 inherited recessively – about 20 subtypes
Facio-Scapulo-Humeral MD pathogenesis
disease occurs due to expression of a protein not naturally present. Presence of reduced number of repeats produces a protein called double homeobox protein 4 (DUX4), which is normally not present.
Myotonic Dystrophy pathogenesis
Underlying genetic defect is due to the phenomenon of anticipation (increasingly larger number trinucleotide repeats in subsequent generations). affects chloride channels in membrane, insulin receptors and protein tau. myotonia, risk of diabetes, cognitive delay. Muscle fibers show altered resting membrane potential
Duchenne MD clinical manifestations
By 2-4 years age, muscles of shoulder girdle, rectus abdominis, pelvic girdle muscle (Gluts), start to get weak. Later distal muscles (hamstring, calf muscles). Gower’s sign, increased lumbar lordosis, Shows pseudohypertrophy of calf muscles, contractures result in toe walking. respiratory muscles get affected, cardiac muscles can also get affected
Becker MD clinical manifestations
Pattern of involvement resemble DMD, but show later onset, slow progression, longer life expectancy
Limb girdle MD clinical manifestations
signs are first noticed in adolescence to adulthood, affects proximal shoulder and pelvic girdle, winging of scapula, lumbar lordosis, abdominal protrusion, waddling gait, ambulation capacity varies widely
congenital MD clinical manifestations
more severe, Symptoms typically present at birth, rapid loss of muscle strength and progressive respiratory symptoms
WWS (Walker Warburg syndrome)
most severe CMD, presents at birth, rapidly progresses and death usually prior to 1 year age, involves ocular impairments, brain abnormalities.
MEB (muscle eye brain) disease
similar clinical findings as WWS but has wider variations, retinal abnormalities, glaucoma, polymicrogyria, cerebellar abnormalities.
Fukuyama CMD
onset at or shortly after birth, progressive weakness and contractures, typical loss of ambulation by 10 years age
Facio-Scapulo-Humeral MD clinical manifestations
mild, onset usually 2nd decade. Inability to close eyes may be first sign, facial flattening, winging of shoulders, difficulty raising arms overhead, most people have normal lifespan
Myotonic Dystrophy clinical manifestations
Typically presents with muscle weakness, wasting and myotonia (delayed relaxation of muscle following contraction)
Myotonic Dystrophy diagnosis
clinical presentation, family hx, genetic testing, EMG studies show “dive-bomber” kind of sound
MD treatment
No known treatment that stops progression, Use of prednisone in DMD/BMD may delay progression and allow child to walk some more years
MD prognosis
Depends on the type of MD, Respiratory muscle dysfunction, cardiac muscle conduction defects are common sources of morbidity and mortality, DMD/BMD, CMD are more severe with shorter life span. People with FSHD and LGMD can expect to have relatively normal life span
MD implications for therapist
Tx is directed towards maintain function for as long as possible, contracture management, encourage activity, muscle strengthening, may be contraindication, breathing ex, later stages may require airway clearance techniques
