Glossary

Common terms in pediatric MNM

Hover-card definitions appear inline on the modality and foundation pages, this is the master list. Search or jump by first letter.

Showing 31 of 31 terms

A

aEEG: Amplitude-integrated EEG. A bandpass-filtered, rectified, time-compressed display of EEG envelope used at the bedside in NICU and PICU.
AMP: ICP pulse amplitude, peak-to-trough of the ICP pulsation, scales with intracranial compliance.
Autoregulation: The brain's ability to maintain approximately constant cerebral blood flow despite changes in MAP or CPP. Plateau spans roughly MAP 60–150 mmHg in healthy adults; narrower and lower in younger children. Mediated by myogenic, metabolic, and neurogenic mechanisms.

BIS: Bispectral Index. Proprietary 0–100 processed-EEG sedation depth marker. SedLine PSI and Narcotrend are alternatives.

CMRO₂: Cerebral metabolic rate of oxygen. Drives CBF in normal coupling; rises ~7 % per °C (Q10 = 1.07).
COx: Cerebral oximetry index. Pearson correlation between MAP and NIRS regional oxygen saturation (rSO₂); fully non-invasive (MAP-based, yields MAPopt). Surrogate for autoregulation, noisier than PRx; complementary in NIRS-only setups.See also: PRx, ORx
CPP: Cerebral perfusion pressure. CPP = MAP − ICP. The driving pressure for cerebral blood flow.
CPPopt: Optimal cerebral perfusion pressure. The CPP at which the moving (CPP, PRx) data over the past 4 hours has its minimum on a parabolic fit, the bottom of the U-shaped autoregulation curve.See also: PRx, CPP
Cushing reflex: Hypertension + bradycardia + irregular respiration produced by brainstem ischemia at very high ICP, a late, ominous sign.

EEG: Electroencephalography. Scalp recording of cortical electrical activity; the only bedside tool that can detect non-convulsive seizures.

FOUR score: Full Outline of UnResponsiveness. Eye, motor, brainstem, respiration, each 0–4 (total 0–16). Better in intubated patients (no verbal component).

GCS: Glasgow Coma Scale. Eye (1–4) + verbal (1–5) + motor (1–6) = 3–15. Pediatric verbal scale modified for pre-verbal children.

ICP: Intracranial pressure. Pressure inside the cranial vault, measured directly by intraparenchymal or intraventricular probe.

L/P ratio: Lactate-pyruvate ratio from microdialysis. > 25 with normal glucose suggests mitochondrial dysfunction; > 40 with low glucose suggests ischemia.
Lindegaard ratio: TCD-derived ratio of MCA mean flow velocity to extracranial ICA velocity. Distinguishes vasospasm (>3) from hyperemia (<3).

MAP: Mean arterial pressure. The time-averaged systemic arterial pressure; the input to CPP.
Microdialysis: Sampling of cerebral interstitial fluid via a semipermeable catheter. Reports glucose, lactate, pyruvate, glycerol, glutamate.
Mx: Mean velocity index. Pearson correlation between MAP and TCD mean flow velocity (MFV), same epoch architecture as PRx. Useful when no ICP probe is available.See also: PRx

NIRS: Near-infrared spectroscopy. Optical regional cerebral oximetry using the modified Beer-Lambert law. Reports rSO₂.
NPi: Neurological Pupil Index. An algorithmic 0–5 score combining pupil size, constriction velocity, latency, and dilation velocity. < 3 is abnormal.

ONSD: Optic nerve sheath diameter. Sonographic measurement 3 mm posterior to the globe. > 5 mm in children > 1 year suggests raised ICP.
ORx: Oxygen reactivity index. Correlation between CPP and NIRS rSO₂; requires an ICP monitor; the CPP-based analog of COx.See also: COx, PRx

PbtO₂: Brain tissue oxygen tension. Direct probe measurement of the partial pressure of oxygen in cerebral white matter. Threshold for concern is 15–20 mmHg.
PRx: Pressure reactivity index. Moving Pearson correlation between 30 consecutive 10-second epoch averages of arterial blood pressure and intracranial pressure, computed over a 5-minute window. Negative or near-zero values indicate intact pressure autoregulation; values > 0.25 are pressure-passive and prognostically poor.See also: Mx, COx, ORx, Autoregulation
PVI: Pressure-volume index. The volume change required to raise ICP by a factor of 10, Marmarou's logarithmic compliance descriptor. ~20 mL adult.

qEEG: Quantitative EEG. Spectrograms, alpha-delta ratio, suppression burst index, asymmetry, quantitative summaries of long EEG runs.

RAP: Compensatory reserve index. Moving Pearson correlation between ICP pulse amplitude (AMP) and mean ICP over a 4-minute window. RAP > 0.6 indicates low compensatory reserve; sudden drop toward zero at high ICP is a decompensation signature.See also: ICP, AMP
rSO₂: Regional cerebral oxygen saturation reported by NIRS. Approximately 70 % venous, 25 % arterial, 5 % capillary in adult cortex.

SjvO₂: Jugular bulb oxygen saturation. Reverse-flow IJ catheter samples blood draining the brain. 50–75 % normal; < 50 % global ischemia, > 75 % hyperemia or low CMRO₂.
Spreading depolarization: A slow (mm/min) wave of cellular depolarization across cortex with massive K⁺ release, transient ECoG suppression, and metabolic stress. Common in TBI, SAH, malignant stroke; emerging therapeutic target.

TCD: Transcranial Doppler. Insonation of the basal cerebral arteries to record flow velocities (PSV, EDV, MFV) and the pulsatility index.