NeuroNeurosurg

Question 1

Neonatal myasthenia gravis:
-Define, incidence, and timing
-presentation
-risk factors
-management

(November 2021)

Answer 1

-transient condition caused by trans-placental passage of maternal IgG antibodies, usually against AChR. 5-20% of infants born to mothers w MG get it. 80% develop symptoms within 24 hours.

-generalized hypotonia, poor suck/swallow, weak cry, ptosis, poor extra-ocular muscle function. Rarely, respiratory problems

-No correlation with maternal severity of disease or antibody concentration. Inverse correlation between maternal disease duration and neonatal incidence. Hx of neonatal MG in a sibling is a risk factor. Maternal thymectomy may be protective against neonatal disease but still warrant NICU observation.

-Supportive care, NG for feeds if needed. In severe cases acetylcholinesterase inhibitors eg neostigmine or pyridostigmine. Exchange or IVIG in severe cases with respiratory depression.

Question 2

IVH in term infants
-incidence of minor vs symptomatic?
-common underlying etiology?
-commonly associated intracranial hemorrhages?

(September 2021)

Answer 2

• About 3-4% term infants have minor IVH vs ~0.04% symptomatic in term infants
• ~1/3 of term infants with symptomatic IVH have underlying cerebral sinovenous thrombosis (CSVT)
• thalamic hemorrhage (~25%) and/or choroid plexus hemorrhage (~35%) bc the deep venous system drains the veins of these structures

Question 3

Cerebral sinovenous thrombosis (CSVT)
-best imaging to diagnose
-pathophysiology
-clinical presentation
-risk factors?
-anticoagulation?

(September 2021)

Answer 3

-magnetic resonance venography (MRV)

-CSVT causes increased pressure proximal to the occluded vein, causing hemorrhagic infarction and IVH

-seizures are most common presenting sign but can be nonspecific and include lethargy, irritability, poor feeding, apnea, abnormal tone

-maternal risk factors include GDM, PEC, chorio, HTN; neonatal risk factors include MSAF, perinatal asphyxia, instrumented delivery, sepsis, dehydration, CHD, ECMO

-AC is indicated certainly if there is propagation of the clot in the cerebral veins. Doesn’t worsen existing IVH

Question 4

What is diaphanoscopy and how is it used?

(January 2022)

Answer 4

Bedside illumination of the skull used as a screening tool in neonates with macrocephaly. >2 cm illumination around the beam or asymmetry of the illumination suggests intracranial pathology (HC, hydrancephaly, porencephaly, subdural effusions, holoprosencephaly, SDH). Diffuse transillumination will occur if cerebral cortex is < 1 cm thick. (+) screen here will require head US +/- MRI, CT, genetics.

Question 5

Hydrancephaly:

-cause
-imaging findings
-exam and prognosis

(January 2022)

Answer 5

~1/10,000 births, isolated event, with near-total loss of cortex attributed to an early in utero vascular accident.

-Imaging shows thin-walled fluid filled cyst, though small asymmetric remnants of the cortex may remain. Brainstem, cerebellum, unfused thalami, and striatum are preserved, +falx cerebri present

-affected infants will have an intact skull that can range from macro with split sutures to microcephalic. Poor prognosis, VP shunt +/- for comfort

Question 6

HSAS (x-linked hydrocephalus caused by stenosis of the aqueduct of Sylvius)

-cause
-presentation
-imaging & prognosis

(January 2022)

Answer 6

• mutation in the L1CAM gene that affects ~1/30,000 male infants

-HC with split sutures, macrocephaly, and adducted thumbs

-CNS imaging shows thin, symmetric rim of cortical tissue, unfused thalami, and falx cerebri is present. Early VP shunt recommended but still may have severe DD