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Toronto Notes 2019 Pediatric Neurosurgery Neurologically Determined Death
Definition
• irreversibleanddiffusebraininjuryresultinginabsenceofclinicalbrainfunction • cardiovascularactivitymaypersistforupto2wk
Criteria of Diagnosis
• prerequisites:noCNSdepressantdrugs/neuromuscularblockingagents,nodrugintoxication/ poisoning, temperature >32oC, no electrolyte/acid-base/endocrine disturbance
• absentbrainstemreflexes:pupillarylightreflex,cornealreflexes,oculocephalicresponse,caloric responses (e.g. no deviation of eyes to irrigation of each ear with 50 cc of ice water – allow 1 min after injection, 5 min between sides), pharyngeal and tracheal reflexes, cough with tracheal suctioning, absent respiratory drive at PaCO2 ≥60 mmHg, ≥20 mmHg rise above baseline, and pH ≤7.28 (apnea test)
• 2evaluationsseparatedbytime,usuallyperformedbytwospecialists(e.g.anesthetist,neurologist, neurosurgeon)
• confirmatorytesting:flatEEG,absentperfusionassessedwithcerebralangiogram
Coma
Definition
• anunrousablestateinwhichpatientsshownomeaningfulresponsetoenvironmentalstimuli
Pathophysiology
• lesionsaffectingthecerebralcortexbilaterally,thereticularactivatingsystemortheirconnectingfibres • focalsupratentoriallesionsdonotalterconsciousnessexceptbyherniation(compressiononthe
brainstem or on the contralateral hemisphere) or by precipitating seizures
Classification
• structurallesions(tumour,pus,blood,infarction,CSF):1/3ofcomas
■ supratentorial mass lesion: leads to herniation
■ infratentorial lesion: compression of or direct damage to the RAS or its projections
• metabolicdisorders/diffusehemisphericdamage:2/3ofcomas
■ deficiency of essential substrates (e.g. oxygen, glucose, vitamin B12)
■ exogenous toxins (e.g. drugs, heavy metals, solvents)
■ endogenous toxins/systemic metabolic diseases (e.g. uremia, hepatic encephalopathy, electrolyte
imbalances, thyroid storm)
■ infections (meningitis, encephalitis)
■ trauma (concussion, diffuse shear axonal damage)
Investigations and Management
• ABCs
• labs:electrolytes,extendedelectrolytes,TSH,LFTs,Cr,BUN,toxinscreen,glucose • CT/MRI, LP, EEG
Persistent Vegetative State
Definition
• aconditionofcompleteunawarenessoftheselfandtheenvironmentaccompaniedbysleep-wakecycles with either complete or partial preservation of hypothalamic and brainstem autonomic function
• “awakebutnotaware”
• followscomatosestate
Etiology/Prognosis
• mostcommonlycausedbycardiacarrestorheadinjury
• duetoirreversiblelossofcerebralcorticalfunctionbutintactbrainstemfunction • average life expectancy is 2-5 yrs
Pediatric Neurosurgery
Spinal Dysraphism
• spinaldysraphismreferstoaspectrumofcongenitalanomaliesresultinginadefectiveneuralarch through which CNS elements are herniated
• the spectrum is divided largely into aperta (visible lesion; no skin covering) and occulta (no visible lesion; skin covering)
Neurosurgery NS35
Thoracolumbar Injury Classification and Severity Scoring
Parameter Points
Morphology
Compression fracture 1 Burst fracture 2 Translational/rotational fracture 3 Distraction 4 Neurologic Status
Intact 0 Nerve root injury 2 Spinal Cord Status
Incomplete 3 Complete 2 Cauda equine 3 Posterior Ligamentous
Complex
Intact 0 Injury suspected/indeterminate 2 Injured 3
• TLICS scoring based on morphology of injury, status of posterior ligamentous complex, and neurological status
• Non-operative management if TLICS = 0-3, operative management if TLICS = 5+, either operative or non-operative if TLICS = 4
Prenatal vs. postnatal repair of myelomeningocele (MMC)
NEJM 2011; 364:993-1004
Methods: RCT comparing prenatal surgery (before 26 weeks of gestation) and standard postoperative surgery. 12-month outcomes included, death or need for placement of a CSF shunt. 30-month outcomes included mental development and motor function.
Results: 40% of prenatal-surgery patients, compared to 82% of postnatal-surgery patients, required CSF shunt (P<0.001). Prenatal surgery resulted in improvement in mental development and motor function (P=0.007). However, prenatal surgery was associated with an increased risk of gynecological complications.
Conclusion: Prenatal surgery for MMC reduced need for shunting and improved motor outcomes but was associated with maternal and fetal risks related to preterm delivery.