CONGENITAL AND BRAIN MALFORMATIONS 1.1 (based on Agsa T) Flashcards
What is important when examining pediatric patients with neurologic problems?
Obtaining a good pediatric neurologic examination, including history taking and physical examination.
What is the first question to ask when a patient presents with a neurologic abnormality?
Do you think that this is a neurologic problem?
What three key questions should the clinician answer using history and diagnostic studies?
- Is there a neurologic problem?\n
- What is the lesion?\n
- If there is a neurologic problem, is it in the upper motor neuron (UMN) or lower motor neuron (LMN)?
What is the most common distinguishing neurologic examination?
Getting the deep tendon reflexes (DTR).
What neurologic finding suggests an upper motor neuron (UMN) problem?
Hyperreflexia.
What neurologic finding suggests a lower motor neuron (LMN) problem?
Hyporeflexia.
What imaging is used for suspected upper motor neuron (UMN) problems?
Neuroimaging such as brain CT scan, brain MRI, and spinal cord MRI.
What tests are used for suspected lower motor neuron (LMN) problems?
Electromyography (EMG) and nerve conduction velocity (NCV).
Why is knowing the temporal profile of a neurologic disease important?
It helps in hypothesizing the nature of the lesion and formulating differential diagnoses.
What temporal profile and symptom might suggest a vascular malformation in a pediatric patient?
A sudden, severe acute headache.
What temporal profile and symptom might suggest a migraine headache?
A chronic headache lasting more than 3 months, occurring on and off.
What question helps determine if a neurologic condition is focal or generalized?
Does it present with one-sided weakness or generalized weakness?
What neurologic condition is suspected in a patient with one-sided paralysis?
A stroke.
What neurologic condition is suspected in a patient with generalized weakness?
A condition affecting the cerebral hemisphere or an ascending paralysis.
What question helps determine if a neurologic condition is progressive or static?
Does the weakness or headache become more severe over time?
What condition is suggested by a static one-sided weakness present since birth?
Cerebral palsy.
What is the significance of the course of illness in diagnosing neurologic disorders?
It helps rule in or rule out particular neurologic disorders and aids in forming a good admitting and differential diagnosis.
What are the key causes of acute neurologic conditions?
Vascular/infarct (focal), hypoxic (diffuse), trauma (focal or diffuse).
What are the key causes of subacute neurologic conditions?
Inflammatory/infectious (focal or diffuse), immune-mediated (focal or multifocal), toxic/metabolic (diffuse).
What are the key causes of chronic neurologic conditions?
Congenital (focal or diffuse), degenerative (diffuse or system-related), neoplastic (focal).
What are the key causes of paroxysmal neurologic conditions?
Seizure (focal or diffuse), vascular/syncope (diffuse), pain/headache (focal or diffuse).
What are common facial features in fetal alcohol spectrum disorders?
Smooth philtrum, thin upper lip, upturned nose, flat nasal bridge, epicanthal folds, small palpebral fissures, and small head circumference.
What does dysmorphism refer to?
An abnormal shape or body feature that differs from normal appearance, often due to genetic or environmental factors.
Who needs a dysmorphology evaluation?
Patients with intrauterine growth retardation, abnormal facial features, congenital anomalies, microcephaly/macrocephaly, developmental delay, unusual behaviors, or significant regression in development.
What is the approach to birth defects and congenital abnormalities?
Recognize abnormalities, make an accurate diagnosis, provide prognosis, discuss management options, and conduct appropriate evaluations.
What is the significance of pedigree evaluation in dysmorphology?
It traces lineage and heritage through family trees to identify genetic conditions.
What physical exam findings suggest low-set ears?
Ears positioned below the line drawn from the bridge of the nose to the lower parts of the nose, often seen in conditions like Down syndrome and Prader-Willi syndrome.
What are common dysmorphic facial features used to diagnose syndromes?
Hypertelorism (wide-set eyes), hypotelorism (narrow-set eyes), epicanthal folds, palpebral fissure abnormalities (upslanted or downslanted).
What condition is associated with upslanted palpebral fissures?
Down syndrome (Trisomy 21).
What condition is associated with downslanted palpebral fissures?
Marfan syndrome or other craniofacial abnormalities.
How is microcephaly defined?
A head circumference of less than 2 standard deviations (SD) below the mean.
What is the normal spacing of the orbits?
The width of one eye should be equal to the intercanthal distance and the space from the outer eye to the edge of the face (1:1:1 ratio).
What are some physical dysmorphic features that may indicate underlying nervous system abnormalities?
Carp mouth (downturned mouth corners), long smooth philtrum (flattened area between upper lip and nose), mandibular asymmetry (uneven jaw structure), disorders of brain growth and size, disorders of skull growth and shape.
What is a single (Simian) palmar crease, and what condition is it associated with?
A single transverse crease across the palm where two main lines merge into one; commonly associated with Down syndrome but not pathognomonic.
What are some other palmar crease variations that are typically seen in normal individuals?
Fused, Sydney, and Hockey-stick creases.
Why is it important to note dysmorphic features during a physical examination?
Most abnormalities originate in utero, and congenital anomalies are often associated with concomitant nervous system anomalies.
What are the major classifications of central nervous system (CNS) malformations?
Neural tube defects and associated spinal cord malformations, encephaloceles, disorders of structure specification, disorders of the posterior fossa, brainstem, and cerebellum.
What is the primary cause of neural tube defects?
Failure of the neural tube to close spontaneously between the 3rd and 4th weeks of gestation.
What are some major risk factors for neural tube defects?
Unknown causes, hyperthermia, drugs (e.g., valproic acid), malnutrition (e.g., folic acid deficiency), maternal obesity, diabetes, genetic mutations affecting folate metabolism.
What are the major types of neural tube defects?
Spina bifida occulta, meningocele, myelomeningocele, encephalocele, anencephaly, caudal regression syndrome, dermal sinus, tethered cord, syringomyelia, diastematomyelia, lipoma involving conus medullaris and/or filum terminale, iniencephaly.
What is spina bifida occulta?
A midline defect of the vertebral bodies without protrusion of the spinal cord or meninges; usually asymptomatic with no neurological signs.
What cutaneous manifestations may indicate spina bifida occulta?
Hemangioma, skin discoloration, pit, lump, dermal sinus, hairy patch.
What imaging is used to diagnose spina bifida occulta?
Spine X-ray shows a defect in closure of posterior vertebral arches and laminae, usually involving L5 and S1. MRI is the best modality for spinal cord evaluation.
What is the best initial screening test for occult spinal dysraphism in neonates?
Ultrasonography.
What is anencephaly, and what causes it?
A condition where the brain is absent due to failure of anterior neuropore closure, leading to anencephaly, which is incompatible with life.
What is myelomeningocele?
A bony defect of the spine containing both meninges and neural elements, resulting from failure of posterior neuropore closure, often in the lumbar, lumbosacral, or thoracic regions.
What is the difference between meningocele and myelomeningocele?
Meningocele involves a bony defect of the spine containing only meninges, while myelomeningocele contains both meninges and neural elements.
What are some causes of myelomeningocele?
Idiopathic causes, nutritional deficiencies (especially folic acid deficiency), environmental factors, and medication use (e.g., valproic acid).
What is the treatment for myelomeningocele?
Multidisciplinary approach including surgery (treatment of choice), supportive care, and prognosis evaluation for recurrence and complications.
What are the possible complications after myelomeningocele surgery?
Hydrocephalus (requiring VP shunting), CNS infections (ventriculitis), surgical risks in pediatric patients.
What is the second division of congenital malformation of the brain?
Disorders of neuronal migration.
What can minor abnormalities in neuronal migration result in?
Little or no clinical consequence (e.g., small heterotropia of neurons).
In neuronal migration, how do neuroblasts migrate?
From the ventricular zone outward following radial glial fibers to their final location.
What can halt neuronal migration and cause abnormalities?
Any form of insult during migration, even minimal, can have a maximum effect.
What severe CNS abnormalities can result from neuronal migration defects?
Mental retardation, seizures, lissencephaly, and schizencephaly (particularly open-lip form).
What is one of the most important mechanisms guiding neuronal migration?
The radial glial fiber system.
What drugs can cause congenital malformations affecting neuronal migration?
(V-A-C-I)
Valproic acid
Aspirin (Cortal)
Ciprofloxacin
Ibuprofen
What is another important mechanism of neuronal migration besides the radial glial fiber system?
Tangential migration of progenitor neurons destined to become cortical interneurons.
What is lissencephaly also known as?
Smooth brain.
What is agyria?
The absence of cerebral convolutions and a poorly formed Sylvian fissure.
What is the appearance of a lissencephalic brain?
It resembles a 3- to 4-month fetal brain.
What causes lissencephaly?
Faulty neuroblast migration during early embryonic life.
What MRI findings are associated with lissencephaly?
Enlarged lateral ventricles and heterotopias in the white matter.
What is schizencephaly?
The presence of unilateral or bilateral clefts within the cerebral hemispheres due to abnormal morphogenesis.
How can schizencephaly present on imaging?
Clefts may be fused or unfused, sometimes continuous with the ventricles (open-lip schizencephaly).
What can unilateral large schizencephaly be mistaken for?
A porencephalic cyst.
What is the key feature of open-lip schizencephaly?
The cleft is continuous with the ventricle and may cause macrocephaly due to CSF production.
What is neuronal heterotopia?
A neurologic congenital abnormality where neurons fail to migrate properly, forming clumps.
What are the subtypes of neuronal heterotopia?
Periventricular nodular heterotopia, subcortical heterotopia (including band-type), marginal glioneuronal heterotopia.
What is a notable clinical feature of neuronal heterotopia?
It often causes intractable seizures or epilepsy.
What is the key distinguishing feature between lissencephaly and schizencephaly?
Lissencephaly = smooth brain;
Schizencephaly = cleft (can be bilateral depending on the lesion).
