The hypotonic infant Flashcards
What’s the difference between hypotonia and muscle weakness?
- Tone: passive resistance to muscle movement. Cannot be changed by voluntary control or exercise.
- Hypotonia: lowered resistance to passive movement when an infant is alert, but not stimulated.
- Weakness: decreased max muscle power than can be generated
***Weak infants are always hypotonic while hypotonic infants may have normal strength
What’s the difference between phasic and postural tone?
- Phasic tone: The passive resistance to movement of the extremities/appendicular structures
- Postural: The resistance to passive movement of the axial muscles (neck, back, trunk, “core”). The prolonged contraction of antigravity muscles in response to low intensity gravity stretch of gravity.
If you have rapid contraction of a muscle in response to high intensity stretch, this is mediated by which type of motor neurons?
Alpha motor neurons
The prolonged contraction of antigravity muscles in response to low intensity stretch of gravity is mediated by _________ and ________ motor neurons.
The prolonged contraction of antigravity muscles in response to low intensity stretch of gravity is mediated by gamma and alpha motor neurons.
The cerbellum is a muscle tone (facilitator or inhibitor). Therefore, damage to the cerebellum results in (hypertonia or hypotonia)
The cerebellum is a muscle tone facilitator. Therefore, damage to the cerebellum results in hypotonia
Midline cerebellum facilitates (axial or appendicular) muscle tone, while lateral cerebellum facilitates (axial or appendicular) muscle tone.
- Midline cerebellum facilitates axial muscle tone
- Lateral cerebellum facilitates appendicular muscle tone.
Red nucleus is a muscle tone (facilitator or inhibitor). Therefore, damage to red nucleus results in (hypertonia or hypotonia)
Red nucleus is a muscle tone inhibitor. Therefore, damage to red nucleus results in hypertonia
Basal ganglia/striatum is a muscle tone (facilitator or inhibitor). Therefore, damage to basal ganglia/striatum results in (hypertonia or hypotonia).
Basal ganglia/striatum is a muscle tone inhibitor. Therefore, damage to basal ganglia/striatum results in hypertonia.
Damage to the motor strip initially causes (hypertonia or hypotonia), followed by ___________.
Damage to the motor strip initially caused hypotonia followed by spasticity.
Tone is passive resistance to muscle tone maintained by which 4 brain structures?
- Cerebellum
- Red nucleus
- Basal ganglia
- Motor strip
When thinking about hypotonia in infants, it may have a cause due to ________, ________, ________, or ________.
When thinking about hypotonia in infants, it may have a cause due to:
- CNS: chromosome disorder (i.e. Prader-Willi, Down syndrome), metabolic dz, spinal cord injury, hypoxic-ischemic injuries (usually during birth)
- Motor neuron
- Peripheral nerve: congenital hypomyelinating neuropathy, familiar dysautonomia, infantile neuraxonal degeneration
- Muscle/NMJ: Muscular dystrophies, myopathies, congenital myasthenia gravis, ifantile botulism
Your history must include TORCH exposure. What does TORCH stand for?
Toxic plasmosis
Other: syphilis, varicella
Rubella
Cytomegalovirus (CMV)
Herpes
Another word for joint fixation at birth
Arthrogryposis. Seen in Zellweger syndrome.
Primitive reflex: what is the moro reflex?
While supporting infant’s neck, quickly lower its head/back to the table and should notice 3 distinct components:
- Spreading out the arms (abductions)
- Unspread the arms (adduction)
- Crying (usually)
*Present up to 6 months
Primitive reflex: You turn the infant’s head to the side and you observe tonic contracture of the arm on the ipsilateral side. This is called a normal ______________ reflex.
Tonic neck fencing reflex. Should be present up to 6-7 months.
Primitive reflex: Describe the suck reflex.
Anything touches the roof of the mouth causing sucking. Present up to 4 months.
Primitive reflex: describe rooting
Anything toucheing side of infant’s mouth and he turns to suck. Present up to 4 months.
Primitive reflex: how long is the grasp reflex present?
Up to 2 months
At what time intervals is the APGAR score assessed?
1 minute, 5 minute, and sometimes 10 mins. Should be a progression from very low score at 1 minute to very high score (hopefully 10) at 5 mins.
What does APGAR stand for and how do you score points?
-
Activity:
- 0: absent
- 1: flexed arms and legs
- 2: active
-
Pulse:
- 0: absent
- 1: <100 bpm
- 2: >100 bpm
-
Grimace:
- 0: floppy
- 1: minimal response to stimulation
- 2: prompt response to stimulation
-
Appearance:
- 0: blue/pale
- 1: pink body, blue extremities
- 2: pink
-
Respiration:
- 0: absent
- 1: slow and irregular
- 2: vigorous cry
Pediatric milestones at age 3 months include…..
- Holds head at 90º in ventral suspension
- Holds an object placed in the hand
- Turns to sound
- Hand regard, laughs, and squeals
***Red flags: lack of social response or vocalization
Pediatric milestones at age 6 months include….
- No head lag on pull to sit; sits with support; in prone position lifts up on forearms
- Palmar grasp of objects; transfers objects hand to hand
- Vocalizations
- May finger feed self
***Red flags: poor head control, floppiness, not reaching
Pediatric milestones at age 12 months include….
- Pulls to stand; ruises; may stand alone briefly; may walk alone
- Puts block in cup, casts about
- 1-2 words imitates adult sounds
- Imitates activities; object permanence established; stranger anxiety established; points to indicate wants
***Red flags: not communicating by gestures, such as pointing; not weight bearing through legs
Describe the traction response test
- Most sensitive measure of postural tone
- Grasp supine infants hands and pull to sitting position
- Normal: Flexion of arms and legs is notable. Head lags, but minimal by 2 months.
- Present at 33 weeks
- Positive traction test is bad: child does not grasp hands or apply resistance with arms, head flops back.
Describe the vertical suspension test
- AKA axillary suspension
- Pick up infant and hold between hands
- Normal: head erect in midline with flexion at knee, hip, ankle
- Hypotonia: infant slips through hands; also can check head control (falls forward)
Describe the horizontal suspension reflex test
- AKA ventral suspension
- Lift infant with one arm under chest and abdomen
- Assessing nuchal and truncal tones
- Normal: some flexion of arms and legs; attempt to lift head
- Abnormal: draped like cloth; no attempt to lift head; no flexion of legs
Characteristic traits of Down syndrome include….
- Trisomy 21
- Epidemiology: 1/800 births (higher risk with older age of parents >35)
- Microgenia
- Macroglossia
- Epicanthic eye folds
- Palmar crease
- Hypotonia
- Congenital heart defects ***need cardiology eval and f/u
- Upturned nose
- Flat nasal bridge
Characteristic traits of Prader Willi include….
- Genetic: paternally derived (usually a deletion)
- Clinical features:
- severe hypotonia
- thin upper lip
- almond shaped eyes
- hyperphagia beginning 1-6 y/o
- Developmental delay - some do, some don’t
- Decreased movement in-utero, weak cry, poor reflexes
Hypoxic-ischemic encephalopathy is defined as APGAR of _____ at 5 minutes
Hyopoxic-ischemic encephalopathy is defined as APGAR of <7 at 5 minutes
Describe Zellweger Syndrome
- Genetic dz (autosomal recessive)
- Inability to process phospholipids or bile acids
- Presents with sever hypotonia, seizures, dysmorphic with high forehead, arthrogryposis
- Diminished or absent tendon reflexes
- Usually die within 1 yr of life
- Lorenzo’s oil
Describe Pompe’s Disease
- Autosomal recessive
- Glycogen storage dz
- Nl development initially, then obvious hypotonia, weakness, decreased movement, poor swallow, pool secretions, absent DTRs
- No tx - pts die by 2 y/o
What are the two kinds of infantile myasthenia gravis?
- Neonatal: maternal antibodies to ACh receptors, resolves with supportive care
- Congenital: difficulty with packaging, delivery or recognition of ACh. Does not go away.
