Brainstem Dysfunction in Chiari Malformation Presenting as Profound Hypoglycemia

Brainstem Dysfunction in Chiari Malformation Presenting as Profound Hypoglycemia AbstractOBJECTIVE:We report four patients whose cases resulted in our observation that profound hypoglycemia resulting from intermittent hyperinsulinism plays a significant role in patients with brainstem dysfunction from Chiari I or II malformations who have intermittent autonomic dysfunction (“blue spells”).METHODS:The records of four children with severe brainstem dysfunction associated with hindbrain herniation (Chiari I or II malformation) were reviewed retrospectively. Each patient had severe lower cranial nerve dysfunction that required tracheotomy and feeding tube placement. After we found that profound hypoglycemia had occurred during a spell of autonomic dysfunction in one patient, the charts of the other three patients were reviewed for evidence of hypoglycemia. Now, whenever one of them has evidence of autonomic dysfunction, prospective studies of glucose and insulin levels are performed. Three of the patients had Chiari II malformation in association with myelomeningocele, and one patient had a Chiari I malformation resulting from Pfeiffer's syndrome.RESULTS:Hypoglycemia occurred in these patients episodically, and usually when their shunts were functioning. The hypoglycemia was associated with hyperinsulinemia in each patient. The brainstem structures of these children (presumably the dorsal motor nuclei of the vagus) were extremely sensitive to changes in local or regional intracranial pressure. These changes were triggered by intermittent shunt failure, agitation from pain, abdominal distention from constipation, and retention of C02. In patients with Chiari malformations, even mild increases in intracranial pressure lead to brainstem dysfunction. One possible explanation is that pressure on the deformed Xth cranial nerve nuclei may lead to insulin release and life-threatening hypoglycemia. Continuous-drip feeds are necessary to prevent this complication.CONCLUSION:Patients with severe intermittent brainstem dysfunction after decompression of Chiari I or Chiari II malformations should have laboratory studies of glucose levels performed at the time of the episodes to rule out hypoglycemia. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Neurosurgery Oxford University Press

Brainstem Dysfunction in Chiari Malformation Presenting as Profound Hypoglycemia

Brainstem Dysfunction in Chiari Malformation Presenting as Profound Hypoglycemia

386 Rekate et al. he Chiari II m alfo rm atio n is a pan­ Brainstem Dysfunction in Chiari cerebral disorder involving anomalies of the entire neuraxis and chondrocra- Malformation Presenting as Profound nium. It is characterized by the ca u d a l displacement of the cerebellar vermis and Hypoglycemia: Presentation of Four tonsils into the cervical canal; elongation, kinking, and caudal displacement of the Cases, Review of the Literature, and lower brainstem below the foramen mag­ num; and upward displacement of the Conjecture as to Mechanism superior cerebellum through a dysplastic, low-lying tentorial incisura. The posterior fossa is small, and the torcula and trans­ verse sinuses are displaced inferiorly, Harold L. Rekate, M.D., Trimurti D. Nadkarni, M.D., usually just above the foramen magnum (14). Patricia A. Teaford, M.D., Donna W allace, R.N., M.S. The m ajor cau se of death in children Division of Neurological Surgery (HLR, TDN, D W ) and Pediatric Critical Care Department (PAT), ( < 2 0 yr) with myelomeningocele seems Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona to be related to brainstem dysfunction (13, 22). During early infancy, these problems frequently include intermittent apnea, cy­ anosis, bradycardia, swallowing disor­ OBJECTIVE: W e report four patients whose cases resulted in our observation ders with drooling and aspiration, nystag­ that profound hypoglycemia resulting from intermittent hyperinsulinism mus, vocal cord paralysis, torticollis, plays a significant role in patients with brainstem dysfunction from Chiari I or II opisthotonos, hypotonia, and spasticity7 malformations who have intermittent autonomic dysfunction ("blue spells"). (19). Sym ptom s of hindbrain dysfunction M ETH O D S: The records of four children with severe brainstem dysfunction may occur at any time during the life of associated with hindbrain herniation (Chiari I or II malformation)...
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Publisher
Congress of Neurological Surgeons
Copyright
© Published by Oxford University Press.
ISSN
0148-396X
eISSN
1524-4040
D.O.I.
10.1097/00006123-199908000-00040
Publisher site
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Abstract

AbstractOBJECTIVE:We report four patients whose cases resulted in our observation that profound hypoglycemia resulting from intermittent hyperinsulinism plays a significant role in patients with brainstem dysfunction from Chiari I or II malformations who have intermittent autonomic dysfunction (“blue spells”).METHODS:The records of four children with severe brainstem dysfunction associated with hindbrain herniation (Chiari I or II malformation) were reviewed retrospectively. Each patient had severe lower cranial nerve dysfunction that required tracheotomy and feeding tube placement. After we found that profound hypoglycemia had occurred during a spell of autonomic dysfunction in one patient, the charts of the other three patients were reviewed for evidence of hypoglycemia. Now, whenever one of them has evidence of autonomic dysfunction, prospective studies of glucose and insulin levels are performed. Three of the patients had Chiari II malformation in association with myelomeningocele, and one patient had a Chiari I malformation resulting from Pfeiffer's syndrome.RESULTS:Hypoglycemia occurred in these patients episodically, and usually when their shunts were functioning. The hypoglycemia was associated with hyperinsulinemia in each patient. The brainstem structures of these children (presumably the dorsal motor nuclei of the vagus) were extremely sensitive to changes in local or regional intracranial pressure. These changes were triggered by intermittent shunt failure, agitation from pain, abdominal distention from constipation, and retention of C02. In patients with Chiari malformations, even mild increases in intracranial pressure lead to brainstem dysfunction. One possible explanation is that pressure on the deformed Xth cranial nerve nuclei may lead to insulin release and life-threatening hypoglycemia. Continuous-drip feeds are necessary to prevent this complication.CONCLUSION:Patients with severe intermittent brainstem dysfunction after decompression of Chiari I or Chiari II malformations should have laboratory studies of glucose levels performed at the time of the episodes to rule out hypoglycemia.

Journal

NeurosurgeryOxford University Press

Published: Aug 1, 1999

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