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Coefficient of variation of R-R intervals in severe brain damage
A Nezu1, S Kimura, T Kobayashi
1Department of Pediatrics, Urafune Hospital of Yokohama City University, Japan.
Insights
The coefficient of variation of R-R intervals (CVRR) can help assess severe brain damage in children. Extremely low CVRR suggests brainstem dysfunction, while high CVRR may indicate other neurological disorders.
Area of Science:
- Pediatric Neurology
- Autonomic Nervous System Function
- Quantitative Neurophysiology
Background:
- Severe brain damage in children presents diagnostic challenges.
- Autonomic nervous system function, assessed via heart rate variability, is often impaired in neurological disorders.
- The coefficient of variation of R-R intervals (CVRR) is a measure of heart rate variability.
Purpose of the Study:
- To investigate the utility of CVRR in quantifying severe neurological damage in pediatric patients.
- To compare CVRR in children with severe brain damage (respiratory insufficiency and severe athetotic cerebral palsy) to neurologically normal controls.
Main Methods:
- CVRR was measured in 18 children with severe brain damage and 22 neurologically normal controls.
- Patients were categorized into a respiratory insufficiency (RI) group (n=10) and a severe athetotic cerebral palsy (SA) group (n=8).
- Statistical analysis, including ANOVA, was used for comparisons.
Main Results:
- CVRR was significantly lower in the RI group (2.19 +/- 1.28%) compared to controls (5.56 +/- 1.53%) (P < 0.01).
- CVRR was significantly higher in the SA group (11.30 +/- 3.91%) compared to controls (P < 0.01).
- Extremely low CVRR (1.00-1.29%) was observed in four patients with brain death, suggesting brainstem dysfunction.
Conclusions:
- CVRR may serve as a valuable quantitative marker for severe neurological disorders in children.
- Extremely low CVRR is strongly associated with brainstem dysfunction, as seen in brain death.
- Further research is needed to determine the cause of elevated CVRR in severe athetotic cerebral palsy.
Abstract:
The coefficient of variation of R-R intervals (CVRR) was studied in 18 children having severe brain damage with a mean +/- standard deviation (s.d.) age of 8.4 +/- 5.9 years, who were divided into ten patients complicated with respiratory insufficiency (RI group) and eight patients with severe athetotic cerebral palsy (SA group). CVRR was obtained in the resting supine position, and was compared with that in 22 neurologically normal controls. CVRR in the RI group (mean +/- S.D., 2.19 +/- 1.28%) was significantly lower than that in controls (5.56 +/- 1.53%), while CVRR in the SA group (11.30 +/- 3.91%) was significantly higher than that in controls (both P < 0.01, ANOVA). In particular, the four patients with brain death showed extremely low CVRR of 1.00-1.29%. Since CVRR was 4.09% in the patient aged 4 years with birth injury of the upper cervical spinal cord causing absence of spontaneous respiration, the extremely low CVRR in patients with brain death may be directly related to brainstem dysfunction. The cause of the high CVRR in the SA group was not determined. Thus, CVRR may be useful for quantitative evaluation of severe neurological disorder.