11/10- Pediatric Neurology Flashcards
What is the most common birth disorder?
- Prevalence
Hearing loss
- 1-2/1000 newborns
What are the complications/morbidities of hearing loss?
Leads to delayed language development, difficulties with behavior and psychosocial interactions, and poor academic achievement
- Early intervention improves language outcomes
- Universal newborn hearing screening identifies congenital hearing loss at an earlier age, allowing for earlier interventions
Describe the classifications of hearing loss
Normal hearing has a threshold of 0-20 dB
- Mild: 20-40 dB
- Moderate: 41-60 dB
- Severe: 61-90 dB
- Profound: > 90 dB
What are the different types of neonatal hearing loss?
- Conductive loss: abnormalities of outer or middle ear
- Sensori-neural hearing loss (SNHL): involves cochlea or auditory neural pathway
- Auditory Neuropathy risk factors
- Severe hyperbilirubinemia
- Neonates admitted to NICU
- Infection, exposure to antibiotics, exposure to Lasix, hypoxia
What is the definition of an effective neonatal hearing screening test?
- Detects hearing loss of > 35 dB
- Reliable in infants under 3 mo
Either:
- Auditory Brainstem response
- Oto-acoustic emissions
Describe auditory brainstem response test - What does it measure
- What % of infants are referred for further eval
- This is needed to detect _____
- Measures the summation of action potentials from CN8 (cochlear nerve) to the midbrain in response to a 35 dB click stimulus
- Approximately 4% of infants screened are referred for further audiologic evaluation
- ABR is the screening test needed to detect auditory neuropathy
What is the technique for doing an auditory brainstem response test?
- Surface electrodes on forehead, nape, and mastoid detect waveform recordings generated by the auditory brainstem response to the click stimuli
- Screening ABR requires up to15 minutes for testing
What do otocacoustic emissions measure?
- Equipment used?
- What % of infants are referred for further eval?
- Measures presence or absence of sound waves (ie, OAEs) generated by the cochlear outer hair cells of the inner ear in response to sound stimuli.
- A microphone at the external ear canal detects these low-intensity OAEs.
- Up to 21% of infants are referred for further audiologic evaluation
What is the technique for doing an otacoustic emissions test?
- Miniature microphone placed in infant’s outer ear canal
- The microphone produces clicks (tones) and detects sound waves as they arise from the cochlea
- Generally requires ~ 4-8 minutes.
Compare ABR and OAE in terms of:
- Test time
- Interference
- False + results
- Auditory neuropathy
- Initial costs
- Overall costs
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What is the hearing screening test recommended for discharge screening?
ABR
What is strabismus?
Anomaly of ocular alignment that can occur in any direction
What is tropia/manifest strabismus?
Present without interruption of the vision (always present)
What is phoria/latent strabismus?
Latent strabismus is present only when fixation is interrupted (sometimes present)
Strabismus results as a violation of what?
One of the major principles that govern ocular motility (Hering’s or Sherrington’s law)
What are the major principles that govern ocular motility (name them)?
- Hering’s law
- Sherrington’s law
What is Hering’s law?
Agonist muscles in opposite eyes receive equal innervation to ensure coordinated binocular eye movements
What is Sherrington’s law?
Agonist/antagonist muscle pairs within each eye receive reciprocal innervation. Thus, when the left medial rectus contracts to adduct the left eye, its antagonist, the left lateral rectus muscle, relaxes
What physical exam components are done for physical exam?
- Pupillary reactivity
- Extraocular movements
- Corneal light reflex
- Cover test
- Cover/uncover test
- Bruckner red reflex
What is the initial screening test for strabismus?
Corneal light reflex (Hirschberg test)
What is the corneal light reflex (Hirschberg test)?
- Used as an initial screen for strabismus.
- Pen light held directly in front of child (about 2 feet way)
- Light reflection should be positioned at the same point in each eye
- Asymmetric of the corneal light reflex is noted if a moderate to large deviation is present.
What is the most important test to find tropias?
Cover test
What is the cover test?
- Most important test to find tropias
- Child fixes on a target
- Covers one eye while observing opposite eye for movement
- A tropia is present if the uncovered eye shifts to refixate on the target when the fellow is covered.
What is the most important test to find phorias?
Cover/uncover (cross-over) test
What is the cover/uncover (cross-over) test?
- Most important test to find phorias
- Child fixes on a target
- Cover one eye while observing opposite eye for movement, then quickly cover the opposite eye
- A phoria is present if there is movement with this maneuver
What is the Bruckner red reflex?
- What does it screen for
- How is it done
Screens for
- Strabismus
- Congenital cataract
- Retinoblastoma
Procedure
- Examiner is ~20 inches away from the child’s face using a direct ophthalmoscope with the largest diameter of light to view both eyes simultaneously.
- Child’s attention is directed toward the ophthalmoscope - RR should be identical in size, shape, color, and hue.
What is psuedostrabismus?
- Most common type
- Occurs in what kinds of kids
- Tests
- Most common is apparent esotropia that typically occurs in children with:
- Wide nasal bridge and/or
- Large epicanthal folds
- It is not a true strabismus, but rather an optical illusion
- Normal ocular alignment is demonstrated by the corneal light reflex and the cover and cross-over tests.
What is amblyopia?
- What causes it
- Affected function
- Age of presentation
Functional reduction in the visual acuity of an eye caused by disuse or misuse during critical period of visual development
- This suboptimal use is frequently due to strabismus but also nerve palsy, refractive errors, cataracts
- Affects both binocularity and depth perception
- Usual age of presentation is between 3-6 yo
- Early diagnosis is critical in achieving good outcome highlighting the importance of early screening
What is treatment for amblyopia?
- Correcting refractory errors with glasses
- Occlusive therapy
- Penalization therapy
What is the most common neurologic disorder of infants and young children? Prevalence?
Febrile seizures
- Occurring 2-4% of children under 5 yo
Febrile seizures are more common with ___ than ____ illness
Febrile seizures are more common with viral than bacterial illness
Describe simple febrile seizures
- Seizure type
- Duration
- Recurrence
- EEG findings
- Return to baseline?
- Risk for epilepsy
- Generalized seizures
- Lasting under 15 minutes
- Not recurring within 24-hrs
- EEG is normal
- Child will return to normal neuro baseline
- Only 1-2% increased risk for epilepsy
Describe complex febrile seizures
- Seizure type
- Duration
- Recurrence
- EEG findings
- Return to baseline?
- Risk for epilepsy
- Focal presentation
- Lasts >15 min
- Multiple episodes within 24 hours
- EEG will be abnormal
- May have prolonged post ictal state or neuro deficits
- Complex Seizures increase the risk for epilepsy up to 5-10%
What are generally accepted criteria for febrile seizures?
- A convulsion associated w/ temp > 38°C
- Age between 3 mo - 6 yrs
- Absence of CNS infection or inflammation
- Absence of acute systemic metabolic abnormality that may produce convulsions
- No history of previous afebrile seizures
Describe the evaluation of febrile seizures
- Position the child on his/her side and wait, if complex seizure then may give Ativan after 15 min
- Treat fever with antipyretics
- Evaluate for source of fever with blood/urine culture and start antibiotics
- +/- spinal tap, EEG, or neuroimaging
What is the prognosis/risks of febrile seizures?
- Simple Seizures only increase risk for epilepsy of 1-2% compared to the general population
- Complex Seizures increase the risk for epilepsy up to 5-10%
Infantile botulism involves impaired function of what?
Neuromuscular junction
What is the etiologic agent of botulism?
Clostridium botulinum
What is seen in infantile botulism
- Cause
- Affects what age of infants
- What factors predispose infants to vulnerability
- Mechanism of disease
- What systems are affected
Caused by intestinal colonization by Clostridium botulinum
- Affects infants between 1 week - 12 months (most between 2-8 months)
- Young age and the absence of competitive bowel flora are factors that predispose to vulnerability
- Produces a neurotoxin that blocks presynaptic cholinergic transmission
- Affecting skeletal, smooth muscle and autonomic function
Describe C. botulinum
- Gram-positive anaerobic rod shaped bacteria
- Bacteria form spores allowing them to survive in dormant state until exposed to conditions that can support growth
- There are seven types of botulism toxin (A through G)
- Only types A, B, E and F cause illness in humans (bad BEAF gives you botulism)
What is the clinical presentation of infantile botulism?
Progressive neuromuscular blockade
- Cranial nerves are affected first, followed by those of the trunk, extremities, and diaphragm
- Parents c/o constipation and poor feeding
- CN dysfunction results in weak gag and suck, less eye movement, pupillary paralysis, and ptosis.
- Autonomic signs include less tearing and salivation, fluctuating heart rate and blood pressure, and flushed skin and respiratory failure
(Does proceed ascending to descending, but don’t have to totally knock out nerves before it moves on)
How is the diagnosis of infantile botulism made?
- Serum samples for botulinum toxin are often negative
- Anaerobic cultures often take up to six days for growth and identification of the organism Isolation of C. botulinum spores and botulinum toxin in the stool
- Electromyography (EMG) can be used to evaluate nerve response
- Decreased responses to stimulation is seen in 92 percent of infants with botulism poisoning, compared with 20 percent of normal infants
What is the treatment for infantile botulism?
- Admission to ICU and monitor for respiratory failure
- For suspected infant botulism occurring in any state, the California Department of Health Services, Infant Botulism Treatment and Prevention Program should be contacted (www.infantbotulism.org/)
- IV Botulism immune globulin, BIG-IV or BabyBIG, a human-derived botulinum antitoxin (DO NOT WAIT TO CONFIRM TESTING)
- Supportive therapy
What is a meningomyelocele?
Neural tube defect:
- Failed closure of the spinal neural tube leading to malformation of the vertebral column and spinal cord, and ultimately the brain
Describe meningomyelocele
- Incidence (world and US)
- Delivery
- Treatment
Incidence
- World-wide: 1-7 per 1000 live births
- US: 0.2 per 1000 births
Neo team at delivery (vaginal vs. C/S)
- Surgical repair and support services (neurology, urology, genetics, neurosurgery, developmental, OT/PT)
What is Arnold-Chiari malformation?
A downward displacement of the cerebellum, brainstem, either alone or together into the foramen magnum and spinal canal
- May be type I - III
What is hydrocephalus?
Excessive amount of cerebrospinal fluid (CSF) accumulates within the cerebral ventricles and/or subarachnoid spaces, which are dilated
Describe the pathophysiology behind hydrocephalus
- Imbalance between the intracranial cerebrospinal fluid (CSF) inflow and outflow
- Caused by obstruction of CSF circulation or inadequate absorption of CSF
- Excessive CSF causes increased ventricular pressure
- Leads to ventricular dilatation
What is obstructive (non-communicating) hydrocephalus?
- Most common mechanism
- Location
- Obstruction is the most common mechanism
- Occurs at the foramen of Monro, at the aqueduct of Sylvius, or at the fourth ventricle.
Describe the pathophysiology behind obstructive (non-communicating) hydrocephalus
- In infancy the skull expands, partially relieving the intracranial pressure
- If hydrocephalus occurs acutely it results in significantly increased intracranial pressure and in more rapid destruction of brain tissue
- As hydrocephalus progresses, edema and ischemia develop in periventricular brain tissue, leading to atrophy of white matter called periventricular leukomalasia (PVL)
- The gyri become flattened, and the sulci become compressed
What are common causes of obstructive (non-communicating) hydrocephalus?
- Chiari II malformations (posterior fossa)
- Infections and tumors (edema)
- Posthemorrhagic hydrocephalus from Intraventricular Hemorrhage
What is a ventriculo-peritoneal shunt?
- The shunt allows CSF to flow from ventricles into to the peritoneum where it is absorbed, bypassing the site of mechanical or functional obstruction
- Infection and malfunction are common and usually require several shunt revisions
What is ETV/CPC?
- Treatment for what
- Procedure
- Success rate
Treatment for hydrocephalus
- Using an endoscope, enter 3rd ventricle
- Perforate the premammillary membrane
- Cauterize choroid plexus
- Very new procedure in US
- With CPC, ~60% success rate at 5 years
- Acute closure is neurosurgical emergency
What is seen here?
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Chiari I malformation showing descent of the cerebellar tonsils
What is seen here?
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Intracranial MRI findings of a child with a Chiari II malformation
What is seen here?
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MRI demonstrating a Chiari III malformation with cervico-occipital encephalocele