Neuro Flashcards
Agenesis of the Corpus Callosum
CC is a bundle of nerve fibers that connect the 2 hemispheres. When absent, the fiber bundles run parallel to the ventricle instead of connecting. Alcohol Exposure can cause (7% of FAS babies have this); may have impairment with abstract reasoning; May be associated with other midline defects or/and aneuploidy. Poor outcomes when associated with other diagnoses
Holoprosencephaly
Most common brain malformation
Occurs in week 5-6 gestation
Incomplete separation of the prosencephalon along one or more of its 3 major planes
Characterized by a single, midline lateral ventricle, incomplete or absent interhemispheric fissure, absent olfactory system, midfacial clefts, facial abnormalities
Lissencephaly
smooth appearance of the cortical surface
presents initially with seizures; other: hypotonia, feeding difficulties, decreased movement, spastic quadriparesis, ambiguous genitalia may also be noted; seizures usually present at 6-12 months of age
Hydrocephalus
When CSF production exceeds CSF absorption, producing ventricular dilation; Most cases result from developmental disorders of the brain and its CSF circulatory system; Major causes include Dandy-Walker Malformation and Alnold-Chiari Malformation
Presentation: enlarged head, bulging anterior fontanelle, separated cranial sutures, “setting sun” eyes, visible scalp veins
Communicating Hydrocephalus
impaired flow distal to the 4th ventricular foramina;
Non-communicating Hydrocephalus
obstruction anywhere upstream of the 4th ventricular foramina
Dandy-Walker Malformation
Consists of 3 major abnormalities:
1) enlargement of the posterior fossa (occipital cranial prominence) with upward displacement of tentorium
2) Cystic dilation of the 4th ventricle
3) partial or complete ACC
Arnold Chiari Malformation
Displacement of the medulla, cerebellum, and fourth ventricle into the cervical canal blocking adequate CSF drainage; almost exclusively seen with open neural tube defects
Craniosynostosis
a premature fusion of one or more sutures of the skull which prevent appropriate brain growth;
concern for airway compromise, intracranial hypertension, obstructive sleep apnea is common; hearing loss can be present in syndromic craniosynostosis
associated syndromes: Crouzon syndrome (brachycephaly, exophthalmos, small maxillary bone), Apert syndrome (craniosynostosis, small maxilary bone, syndactyly of hands/feet, Pffifer syndrome (like the other 2+plus additional dysmorphisms)
Scaphocephaly
Sagittal craniosynostosis is most common (creates an elongated appearance of the skull) 4x more common in males
Plagiocephaly
coronal craniosynostosis - coronal suture fusion
unilateral - which results in asymmetry of the eyes, forehead, and nose, flattening of forehead on one side)
bilateral - flattening and widening of the skull
Metopic Craniosynostosis
Triangular shaped head with a point at the forehead
Anencephaly
a complete failure of the rostral neuropore to close, leaving the remainder of the brain atrophied; 3/4s are stillborn, palliative care for those born alive
Encephalocele
occurs w/I 26 days of conception, cranial skull defects allow protrusion of the brain contents through the skull; surgical correction indicated
Meningocele
a protrusion of the meninges through a defect in the spine; most commonly noted in the thoracic portion of the spine; folic acid supplementation has been known to decrease this defect
myelomeningocele
protrusion of meninges and spinal cord through a defect in the spine; 3/4 of these defects are located in the lumbar region; higher the location, poorer the prognosis; Increased AFP levels may be indicative of MMC; usually associated with hydrocephalus, some association with trisomy 18 or Chiari malformation type 2
Myotonic Dystrophy
most common disorder affecting musculature; autosomal dominant passed on by mother that worsens with each generation;
Most common features; respiratory and feeding difficulties, arthrogryposis (especially of the lower extremities), symmetrical facial paralysis, normal to large size head
Spinal Muscular Atrophy Syndromes
autosomal recessive disorders; degeneration of the anterior horn cells in the spinal cord and motor nuclei of the lower brainstem; SMA type 1 - Werdnig-Hoffman Disease - defined by onset before 6 months, inability to sit up unassisted, death usually by age 2;
generalized weakness, characteristic frog leg posture, distention of the abdomen, paradoxical breathing; tracheostomy and mechanical ventilation usually required
Subdural Hemorrhages
most likely to occur with rapid deforming stresses (most likely during delivery or difficult extraction) large head /small birth canal, abnormal presentation (breech, face, brow)
Presentation: large infant, low 1 minute Apgar, stupor, coma, bradycardia, ataxic respirations, resp arrest, facial paralysis, seizures, nuchal rigidity, unequal pupils, no dolls eye response
Treatment: rapid surgical evacuation of the blood, subdural tap
Subarachnoid hemorrhage
most common bleed; preterm infants > term infants, blood in the Pia-arachnoid space over the cerebral convexities, pathogenesis unclear, thought be related to trauma, or premature circulation events;
Presentation: minimal or no clinical signs, hydrocephalus can occur, seizures can occur in term infants w/ onset on day 2
usually these infants have sustained severe perinatal asphyxia or trauma
management is essentially that of post-hemorrhagic hydrocephalus; good prognosis
intracerebellar hydrocephalus
preterm infants>term infants;
symptoms w/I first 24 hours of life w/ larger hemorrhages, symptoms consistent with brainstem compression such as apnea, respiratory irregularities, Bradycardia, full fontanelles, separated sutures, dilated ventricles in MRI; thrombocytopenia
Intraventricular Hemorrhage
premature infants at risk due to poor cerebral autoregulation;
Catastrophic syndrom: falling Hct, bulging anterior fontanelle, hypotension, bradycardia, apnea, temp instability, metabolic acidosis, innaproriate ADH secretion, generalized tonic seizures, pupils fixed to light, flaccid quadraparesis, decerebrate posturing,
Grade 1 IVH
Hemorrhage into the subependymal germinal matrix where a hematoma forms (bleeding near the ventricle)
Grade 2 IVH
Bleeding into the lateral ventricle, <50% of the ventricle fills with blood
Grade 3 IVH
Blood fills >50% of the ventricle, ventricular dilation begins and begins to affect brain material
Grade 4 IVH
An infarct or stroke into the periventricular white matter; Changes in hemodynamics precede the bleeding and have revealed a pattern of hypo perfusion-reprofusion cycle (an important causative pathway)
Guidelines for IVH screening
CUS for all infants born at less than 30 weeks be screened at day of life 7-14 and again at 36-40weeks CGA
Outcomes of hemorrhages
- post ventricular hydrocephalus
- periventricular leukomalacia
- cerebral palsy
Periventricular leukomalacia
areas of necrosis that form cysts in the deep white matter and often occur adjacent to the lateral ventricles. areas of paucity of white matter, thinning of the corpus callosum, ventriculomegaly, and delayed myelination; major long term morbidity with PVL is spastic diplegia
Leading Cause of neonatal brain injury and neonatal mortality
hypoxic-ischemic injury
Sarnat Stage 1
Mild encephalopathy
characterized by “hyperalert” infant, blank stare, normal EEG
Sarnat Stage 2
moderate encephalopathy present; obtunded with low tone, weak suck, constricted pupils, decreased moro reflex, often have clinical seizures
EEG shows periodic pattern sometimes preceded by continuous delta activity
Sarnat stage 3
severe encephalopathy; appear stuporous with flaccid tone, intermittent decerebrate posturing, absent reflexes, poorly reactive pupils
Seizure presentation in HIE
presents within 6-12 hours in 50-60% of infants
Typical blood gas for Neonates with HII after sustaining intrapartum event
cord blood pH <7.0 or base deficit greater than or equal to 12-15 mmol/L
The diving reflex
occurs during experimental asphyxia to maintain blood flow to vital organs such as the brain at the expense of less-vital organs
Imaging after HII insult
Conventional MRI shows abnormalities within 3-4 days
seizure associations
with a markedly accelerated cerebral metabolic rate
an increase in lactate
decrease in high energy phosphate compounds
clonic seizure
rhythmic movements of muscle groups which consists of muscle groups which consist of a rapid phase followed by a slow return movement; repetitive and rhythmic jerking movements that can affect any part of the body.
Multifocal or migratory clonic seizures
spread over body parts either in a random or anatomic fashion. may alternate from side to side
Myoclonic seizures
are demonstrated by movements which are rapid, lightning fast jerks; lack the slow return of clonic movements
multifocal myoclonic seizures
asynchronous twitching of several parts of the body
generalized myoclonic seizures
bilateral jerks of flexion of upper (occasionally lower) limbs
