, Rohit Arora3, 4, Nicholas L. DePace5 and Aaron I. Vinik6
(1)
Autonomic Laboratory Department of Cardiology, Drexel University College of Medicine, Philadelphia, PA, USA
(2)
ANSAR Medical Technologies, Inc., Philadelphia, PA, USA
(3)
Department of Medicine, Captain James A. Lovell Federal Health Care Center, North Chicago, IL, USA
(4)
Department of Cardiology, The Chicago Medical School, North Chicago, IL, USA
(5)
Department of Cardiology, Hahnemann Hospital Drexel University College of Medicine, Philadelphia, PA, USA
(6)
Department of Medicine, Eastern Virginia Medical School Strelitz Diabetes Research Center, Norfolk, VA, USA
P&S monitoring provides a description of the neurological development. The literature suggests varying maturation rates of the P and S systems. SNS control seems to mature earlier in fetal life than does PSNS control, whereas cholinergic and adrenergic tones exerted on the resting HR at term are nearly balanced. A pronounced increase in PSNS activity is demonstrated after birth, with a concomitant and relative decrease in SNS activity as compared with the PSNS as well as with the fetus. This is consistent with the notion that, within the ANS, growth is mediated primarily through the PSNS. In full-term neonates, differences in the breathing pattern also affect HRV [1].
As shown in the trend plots in the “Sample Normals” section, parasympathetic dominance seems to persist throughout the early years of a person’s life. This is associated with growth and development. Parasympathetic dominance gives way to sympathetic dominance during the “transition years” between ages 19 and 21. Parasympathetic dominance returns in normal, healthy individuals in the geriatric years and is known to be cardioprotective. Parasympathetic dominance seems to be associated with a (reflexive) elevation in sympathetic activity. For this reason, pediatric resting (initial baseline) normal ranges are elevated with respect to those for adults. Both P&S measures (RFa and LFa, respectively) at rest are considered normal from 2.0 to 15.0 bpm2 (as compared with the adult ranges from 1.0 to 10.0 bpm2, with 0.5–1.0 bpm2 being borderline).
Pediatric parasympathetic dysfunction may present as:
Colic (parasympathetic insufficiency) as an infant
Obesity (PE)
Abnormal menses (in females)
Other hormonal disturbances (in either gender)
Sleep disturbances (either parasympathetic insufficiency or PE)
Depression (PE) and syndromes which seem to include depression-like symptoms, including ADD/ADHD, anxiety, bipolar disorder, and manic–depression disorders
“Growth spurts,” or periods of time when the PSNS is supposed to be more active, can mask a persistent underlying parasympathetic dysfunction. As a result, different manifestations of parasympathetic dysfunction may be diagnosed as different disorders and therefore treated in isolation. Considering the patient’s history from birth may elucidate the underlying autonomic imbalance. When the autonomic dysfunction is treated, the result may be lower-dose and shorter-term therapy. The therapy should then establish and maintain proper SB. Assuming no end-organ effects (causing the autonomic imbalance) and utilizing the plasticity of the ANS, the ANS may be retrained to maintain a proper balance for the individual patient, enabling the patient to carry forward without medications.
For example, consider a female teenager with sleep and menses disturbances, e.g., nighttime sleeplessness and dysmenorrhea, respectively. She may be treated for these two conditions with multiple medications, with apparent relief of symptoms, but no apparent cure. Upon further questioning of the mother, it is discovered that the patient had colic as an infant and sleep difficulties for a short time as a child, around age 7 or 8. Collectively, this points to a possible parasympathetic insufficiency that was present at birth. It may also be passed on from the mother, since tendencies for autonomic disorders seem to be hereditary. Treating the parasympathetic insufficiency may relieve the symptoms, enabling the patient to (eventually) discontinue all medications.
Heretofore, pediatric parasympathetic dominance and parasympathetic excess (PE) have been difficult to differentiate. Since PE is also associated with depression and syndromes which seem to include depression-like symptoms, this may explain the current rate of antidepressant and anticholinergic prescriptions in pediatric patients and perhaps the apparent rise in the suicide rate. Given the very dynamic nature of the pediatric ANS, if a patient has been prescribed an antidepressant for 3 months or more and a PE persists (either at rest or during Valsalva or stand), then the patient may not be responding to that medication; it may only be masking symptoms. This seems to be especially true for those patients whose loved ones report knowing when the patient is “off their meds” after the patient has been prescribed them for more than 3 months. This suggests that the medication has been masking the symptoms, but perhaps not treating an underlying cause: PE. This seems especially true for SSRIs. Switching to another class of antidepressant (e.g., SNRIs or tricyclics) often will also address the underlying PE. Once the PE is relieved, many patients begin to self-wean, by skipping doses, without any notice of being “off their meds.” When switching class medications, consider lower dose, as too much may push the balance too far in the other directions causing different symptoms.