A Provocative Test to Determine Brain Compliance in the Management of Patients with Hydrocephalus

Manwaring, Preston; Manwaring, Jotham; Manwaring, Kim H.; Manwaring, M.

doi:10.1109/iembs.2005.1616037

Cited by 3 publications

(3 citation statements)

References 4 publications

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“…Since this artery originates from intracranial space, changes in intracranial compliance are evident in its blood ow. When ICP was increased by tilting, changes in the blood ow pulse waveform and tympanic membrane pulsation waveform were found to be similar [49], further supporting the results of the current study. Hyperventilation is associated with reduced partial pressure of arterial CO 2 and decreases the subject's ICP level [35].…”

Section: Discussionsupporting

confidence: 87%

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Noninvasive Detection of Elevated ICP Using Spontaneous Tympanic Membrane Pulsation

Dhar

Sandler

Manwaring

et al. 2021

Preprint

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Neurological conditions such as traumatic brain injury (TBI) and hydrocephalus may lead to intracranial pressure (ICP) elevation, which can result in severe headaches, blurred vision, moving or talking problems, seizures and even death. Due to these potential risks, prompt medical attention and reliable monitoring would be needed when elevated ICP is suspected. Current diagnosis methods rely on direct pressure measurement, while CT, MRI and other expensive imaging may be used. However, these invasive or expensive testing methods are often delayed because the above symptoms are non-specific. In addition, invasive methods, such as intraventricular catheter, subdural screw, epidural sensor, lumbar puncture, are associated with an increased risk of infection and hemorrhage. On the other hand, noninvasive, low-cost, accurate methods of ICP monitoring can help avoid risks and reduce costs while expediting diagnosis and treatment. The current study proposes and evaluates a novel method for noninvasive ICP monitoring using tympanic membrane pulsation (TMp). These signals are believed to be transmitted from ICP to the auditory system through the cochlear aqueduct. Fifteen healthy subjects were recruited and TMp signals were acquired noninvasively while the subjects performed maneuvers that are known to change ICP. When elevated ICP was induced, significant TMp waveform morphological changes were observed in each subject (p < 0.01). These changes include certain waveform slopes and high frequency wave features. The observed changes were reversed by the maneuvers that decreased ICP (p <.01). The study results suggest that TMp waveform measurement and analysis may offer an inexpensive, noninvasive, accurate tool for detection and monitoring of ICP elevations. Further studies are warranted to validate this technique in patients with pathologically elevated ICP.

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Section: Discussionsupporting

confidence: 87%

“…10). Manwaring et al acquired pulsation of the supraorbital artery just above the eye from subjects on the tilt table using an oximeter [49]. Since this artery originates from intracranial space, changes in intracranial compliance are evident in its blood ow.…”

Section: Discussionmentioning

confidence: 99%

Noninvasive Detection of Elevated ICP Using Spontaneous Tympanic Membrane Pulsation

Dhar

Sandler

Manwaring

et al. 2021

Preprint

View full text Add to dashboard Cite

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“…However, to date, none have proven to be reliable enough for clinical practice [ 2 , 4 - 7 ]. One technique of interest is the use of tympanic membrane pulsation for ICP derivation [ 8 , 9 ]. The technique, first described in the 1970s, makes use of a known channel between the cerebrospinal fluid (CSF) and the middle ear via the cochlear aqueduct [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

The "Brain Stethoscope": A Non-Invasive Method for Detecting Elevated Intracranial Pressure

Kostick¹,

Manwaring²,

Dhar³

et al. 2021

Cureus

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Introduction Minimally invasive intracranial pressure (ICP) screening has long been desired by neurosurgeons. A novel approach deriving ICP from tympanic membrane (TM) pulsation may offer the solution. The ICP waveform appears to be transmitted to the TM by the cochlear aqueduct. The resulting TM infrasonic pulsations can be measured by certain sensors. Elevated ICP alters brain compliance, which appears to yield slower rise times of the TM pulsation waveform. Measurement of this change may be useful in screening for elevated ICP. This paper investigates one such technique. Methods A stethoscope was modified for airtight external ear canal fit; the dome was exchanged for a magnetic reluctance pressure sensor, allowing measurement of TM pulsations. Analog TM pulsations were analyzed by measuring the pulsation's slope ratio between the waveform’s downslope and upslope. Seventeen normal subjects (ages 18-32 years) underwent hyperventilation and tilt table testing to induce ICP changes. An algorithm processed this data and predicted the subject's ICP status. Results The slope ratio method showed consistent and stable changes with the expected alterations in ICP from the tilt test and hyperventilation maneuvers. The classification algorithm correctly identified subjects with elevated ICP in 60 of 60 independent recordings on 17 subjects. Conclusion This paper has four conclusions. First, the "brain stethoscope" can detect increased ICP from the TM pulsation waveform in healthy subjects. Second, analysis of the TM waveform using slope ratio calculations is capable of distinguishing normal versus elevated ICP. Third, the tilt and hyperventilation maneuvers showed the expected physiologic trends. Last, further studies are needed on patients with pathological ICP before the brain stethoscope can be implemented into clinical practice.

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Noninvasive detection of elevated ICP using spontaneous tympanic membrane pulsation

Dhar

Sandler

Manwaring

et al. 2021

Sci Rep

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Neurological conditions such as traumatic brain injury (TBI) and hydrocephalus may lead to intracranial pressure (ICP) elevation. Current diagnosis methods rely on direct pressure measurement, while CT, MRI and other expensive imaging may be used. However, these invasive or expensive testing methods are often delayed because symptoms of elevated ICP are non-specific. Invasive methods, such as intraventricular catheter, subdural screw, epidural sensor, lumbar puncture, are associated with an increased risk of infection and hemorrhage. On the other hand, noninvasive, low-cost, accurate methods of ICP monitoring can help avoid risks and reduce costs while expediting diagnosis and treatment. The current study proposes and evaluates a novel method for noninvasive ICP monitoring using tympanic membrane pulsation (TMp). These signals are believed to be transmitted from ICP to the auditory system through the cochlear aqueduct. Fifteen healthy subjects were recruited and TMp signals were acquired noninvasively while the subjects performed maneuvers that are known to change ICP. A custom made system utilizing a stethoscope headset and a pressure transducer was used to perform these measurements. Maneuvers included head-up-tilt, head-down-tilt and hyperventilation. When elevated ICP was induced, significant TMp waveform morphological changes were observed in each subject (p < 0.01). These changes include certain waveform slopes and high frequency wave features. The observed changes were reversed by the maneuvers that decreased ICP (p < .01). The study results suggest that TMp waveform measurement and analysis may offer an inexpensive, noninvasive, accurate tool for detection and monitoring of ICP elevations. Further studies are warranted to validate this technique in patients with pathologically elevated ICP.

show abstract

A Provocative Test to Determine Brain Compliance in the Management of Patients with Hydrocephalus

Cited by 3 publications

References 4 publications

Noninvasive Detection of Elevated ICP Using Spontaneous Tympanic Membrane Pulsation

Noninvasive Detection of Elevated ICP Using Spontaneous Tympanic Membrane Pulsation

The "Brain Stethoscope": A Non-Invasive Method for Detecting Elevated Intracranial Pressure

Noninvasive detection of elevated ICP using spontaneous tympanic membrane pulsation

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