Vagus Nerve (Cranial Nerve X)

Kiera is very tired today.  Typically, we find that the day after she returns home from Children's Hospital, she naps the day away.  Today is no exception.  Given this, Kiera is much happier at home.  She loves playing with Piper and going for walks, giving everyone smiles along the way.

The endocrinologist on Kiera's case has prescribed a medication, diazoxide, that is supposed to bring down the level of insulin in Kiera's body.  Kiera's pancreas is producing 10 times the normal amount of insulin, which brings down her blood glucose to dangerously low levels.  Unfortunately, the medication also has the effect of reducing blood pressure so we took Kiera to the local hospital to get her pressure measured.  The mid-morning reading was high and the mid-afternoon reading was on the high side of normal.  Kiera's blood sugar readings have also been fine this afternoon but they always are in the afternoon.  So, the medication might be working but we will not know for sure until tomorrow morning.  Kiera only has low blood sugar levels after feeding -- it is never low after fasting (e.g., overnight fasting).  This has the doctors stumped because although the cornstarch is helping control the dumping syndrome's hyperglycemia, Kiera still has these abnormal lows after breakfast.

Our research suggests that Kiera's hyperinsulinemia hypoglycemia is caused by the stimulation of her vagus nerves.  The vagus nerve is either one of two cranial nerves extending from the brain all the way to our internal organs (or viscera) with branching nerves to the heart, lungs, larynx, stomach, pancreas, and ears, among other body parts.  The vagus nerve transmits sensory information to the brain and also sends outgoing information which governs a range of reflexes.  The vagus nerve helps to regulate heart rate, control muscle movement (particularly mouth muscles for speech), breathing, and sweating.  It is also responsible for keeping the digestive system (e.g., gastrointestinal peristalsis) in working order. 

When the vagus nerve is stimulated, the response is often a reduction in heart-rate or breathing.  In some cases, excessive stimulation can cause someone to have what is known as a vaso-vagal response, appearing to fall into a faint or coma because the heart rate and blood pressure drop so much.  Kiera's blood pressure and heart rate are typically high but she often becomes very sleepy and uncomfortable during feeding.  We believe that Kiera's dumping syndrome is under control using cornstarch but that the vagus nerve is being excessively stimulated during feeding because of her hiatus hernia and her gastroesophageal reflux.  We hope that the fundoplication will solve her discomfort during feeding and her low blood sugar and high insulin levels as well.