Aggressive surgical management of patients with Chiari II malformation and brainstem dysfunction.

Rahman M, Perkins LA, Pincus DW. Aggressive surgical management of patients with Chiari II malformation and brainstem dysfunction. Pediatric Neurosurgery. 2009;45(5):337-44. 11.

BACKGROUND/AIMS:
Chiari II malformation represents a group of developmental abnormalities involving the caudal displacement of the cervicomedullary junction, pons, fourth ventricle, and medulla. This constellation of malformations is strongly associated with myelomeningocele (MM) and is a known cause of neurologic deterioration in older MM patients. We describe the evaluation and management of 4 adult MM patients who presented with brainstem compression and a retroflexed odontoid who were subject to aggressive surgical management including occipitocervical (OC) fusion with good clinical results.

METHODS:
Four MM patients who underwent OC fusion for new-onset brainstem dysfunction and myelopathy were identified in the practice of the principal investigator (D.W.P.) from 2003 to 2008.

RESULTS:
The initial evaluation of these patients included consideration of other diagnoses, such as hydrocephalus due to shunt malfunction and tethered cord. These patients were treated with aggressive surgical management. In some cases, multiple surgeries were performed. All 4 patients were treated with cervical decompression and OC fixation and initially had good outcomes. No patients required transoral decompression. Three of the 4 had stable improvement at their last follow-up appointment (mean follow-up of 9 months).

CONCLUSION:
Late deterioration in older MM patients may be secondary to brainstem or cervical spinal cord compression from ventral odontoid compression and Chiari II malformation, hydrocephalus, hydromyelia, or tethered cord. These patients may benefit from more than one surgery. Posterior decompression and OC fusion can avoid a morbid transoral odontoid resection, greatly improve patients' symptoms and prevent further neurologic decline.

PMID: 19907196

Symptom recurrence after suboccipital decompression for pediatric Chiari I malformation: analysis of 256 consecutive cases.

McGirt MJ, Attenello FJ, Atiba A, Garces-Ambrossi G, Datoo G, Weingart JD, Carson B, Jallo GI. Symptom recurrence after suboccipital decompression for pediatric Chiari I malformation: analysis of 256 consecutive cases. Childs Nerv Syst. 2008 Nov;24(11):1333-9.

OBJECTIVE:
Symptom recurrence remains a problem for some patients after surgical decompression for Chiari I malformation. We set out to identify variables at presentation that could identify subgroups most likely to experience incomplete symptom relief after hindbrain decompression for Chiari I malformation.

MATERIALS AND METHODS:
We retrospectively reviewed the records of all pediatric patients undergoing first-time suboccipital decompression for Chiari I malformation over a 10-year period. Measured outcomes included (1) persistence or recurrence of symptoms regardless of severity and (2) need for revision decompression.

RESULTS:
Two hundred fifty-six children (10 5 years old) underwent surgery for Chiari I malformation and were followed up for a mean of 27 months. Presenting symptoms included headache in 192 (75%) patients and brainstem or cranial nerve symptoms in 68 (27%) patients. Fifty-seven (22%) patients experienced mild to moderate symptom recurrence. Nineteen (7%) patients required revision decompression for significant symptom recurrence. Headache was 70% more likely to persist or recur versus cranial nerve or brainstem symptoms (relative risk 1.70, p < 0.05). Vertigo and frontal headache independently increased the odds of symptom recurrence 2.9- and 1.5-fold, respectively. Each increasing year of preoperative headache duration was independently associated with 15% increase in likelihood of symptom persistence (p < 0.05). Severe tonsilar ectopia (caudal to C2 lamina) was twice as likely to require revision decompression (14% versus 6%). CONCLUSION: In our experience, recurrence of mild symptomatology not severe enough to justify revision surgery may occur in nearly a fifth of patients after surgery. Headache was more likely to recur than objective cranial nerve or brainstem symptoms. Increasing duration of headaches, frontal headaches, and vertigo may be more refractory symptoms of Chiari I malformation. PMID: 18516609

The Chiari II malformation: cause and impact

McLone DG, Dias MS. The Chiari II malformation: cause and impact. Child's Nervous System. 2003 Aug;19(7-8):540-50. Epub 2003 Aug 12.

INTRODUCTION: It is the Chiari II malformation and its effects that determine the quality of life of the individual born with spina bifida.

DISCUSSION: The cause of this malformation has been a source of debate for many years. Understanding the cause enables strategies for the management of problems created by this malformation to be developed. An open neural tube defect allows fluid to escape from the cranial vesicles, altering the intracranial environment and leads to all of the brain changes seen in the Chiari II malformation. Decompression of the intracranial vesicles causes overcrowding, decrease in the size of the third ventricle, and changes in the fetal skull. It also permanently links the intracranial ventricular system to the spinal cord central canal.

PMID: 12920543

Revision surgery for Chiari malformation decompression

Mazzola CA, Fried AH. Revision surgery for Chiari malformation decompression. Neurosurgical Focus. 2003 Sep 15;15(3):E3. Review.

Chiari malformations comprise four different hindbrain anomalies originally described by Hans Chiari, a professor of pathology at the German University in Prague. There are four basic Chiari malformations. The reasons for revision of Chiari malformation decompression may be for conservative or inadequate initial decompression or the development of postoperative complications. Another reason involves cases of both hindbrain herniation and syringomyelia in patients who have undergone adequate posterior fossa decompression without resolution of symptoms, signs, or radiological appearance of their syrinx cavity. Additionally, symptom recurrence has been reported in association with various types of dural grafts. Reoperation or revision surgery for patients with Chiari malformations is common and may not be due to technical error or inadequate decompression. The types of revision surgeries, their indications, and initial presentations will be reviewed.

PMID: 15347221