Previous studies have suggested significant correlation between baseline TMD measurements, derived through stimulation of the stapedial reflex, and direct ICP measurements, albeit with concerns over significant intersubject variability ( 5). These nanolitre (10 −9 l) displacements can be detected by the TMD analyzer through an air displacement sensor probe sealed onto the external auditory meatus. The resultant change in perilymphatic pressure dynamics causes alteration in the kinematics of the middle ear ossicles causing volume displacements of the tympanic membrane ( 3, 4). The TMD analyzer utilizes the communication between the subarachnoid space and the inner ear through the cochlear aqueduct which allows for transmission of ICP dynamics to the perilymphatic space ( 2). Intra-aural pressure measurements using the Tympanic Membrane Displacement (TMD) analyzer may be of value in noninvasive monitoring of ICP dynamics, and in identifying patients at greatest risk of intracranial herniation. Noninvasive tools could circumvent these limitations, provide insights into the pathophysiology of these encephalopathies, and allow for development of appropriate interventions to improve outcome. Their use is complicated by probe displacement, hemorrhage, and infection, which are particularly pertinent limitations in resource poor sub-Saharan Africa ( 1). However, tools for monitoring ICP are invasive and require technical proficiency to ensure safety and accuracy, and cannot therefore be placed promptly in the acutely unconscious patient at risk of herniation. Intensive monitoring of ICP may help to identify patients at risk of herniation and improve outcome. Indeed, catastrophic intracranial herniation is well described in association with a variety of encephalopathic illnesses, and is a real risk in the acute setting, including well-resourced setups. It impairs cerebral perfusion, leading to ischemic brain injury, and may result in death due to intracranial herniation.
Raised ICP is common in all these encephalopathies. Predictors of poor outcome include deep coma, recurrent seizures, shock, and raised intracranial pressure (ICP). These diseases are associated with high mortality and neurocognitive sequelae among survivors. In sub-Saharan Africa, it is most frequently caused by cerebral malaria (CM), acute bacterial meningitis (ABM), and viral encephalitides. Raised TMD pulse pressure measurements are associated with death and may be useful in detecting and monitoring risk of intracranial herniation and intracranial pressure in childhood coma.Īcute coma is a common severe neurological presentation of infectious diseases in children. Adjusting for diagnosis, every 50 nl rise in both semirecumbent and recumbent CPA was associated with increased odds of death associated with intracranial herniation (OR: 1.61, 95% confidence interval (CI): 1.07, 2.41 P = 0.02 and OR: 1.35, 95% CI: 1.10, 1.66 P ≤ 0.01 respectively). We recruited 75 children (32 (43%) females median age 3.3 (IQR: 2.0, 4.3) years). We examined middle ear function using tympanometry and measured cardiac pulse (CPA) and respiratory pulse pressure amplitudes (RPA) using the TMD analyzer.
#INTRA AURAL SERIAL#
Methods:īetween November 2007 and September 2009, we made serial TMD measurements and clinical observations on children with acute coma (Blantyre coma score (BCS) ≤ 2) on the pediatric high dependency unit of Kilifi District Hospital, and on well children presenting to the hospital’s outpatient department for routine follow-up.
We explored the relationship between tympanic membrane displacement (TMD) measurements, a tool to monitor intracranial pressure noninvasively, and clinical features and death in children with acute coma in Kilifi, Kenya.
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