Primary and secondary management of the Chiari II malformation in children with myelomeningocele

Abstract

Chiari malformation type II is almost exclusively found in patients with open spinal dysraphism. Etiology and pathophysiology are not yet completely understood, and management guidelines regarding the best follow-up and treatment of this pathological entity do not exist. In order to assess essential management aspects, literature and a series of secondary neurosurgical interventions in Chiari II patients have been reviewed. A literature review regarding etiology, diagnostics, pathophysiology, and management of Chiari malformation type II (CMII) and a retrospective evaluation of a series (2009-2012) of secondary interventions in Chiari II patients have been performed. Inclusion criteria were ICD for myelomeningocele with or without hydrocephalus and ICD for Chiari malformation and neurosurgical OR procedure. Evaluated parameters were: patient demographics, primary management, secondary neurosurgical operations (cranio-cervical decompression, shunt revision, myelolysis) as well as specific findings pre- and postoperatively. Essential results from literature review and patients' series are compiled in order to define management recommendations. Fifty patients (28 f, 22 m; mean age, 7.1 years (range, 0.5-26 years)) with myelomeningocele-associated Chiari malformation type II were operated on between 2009 and 2012. Twenty-four patients had syringomyelia and scoliosis each, and 12 suffered from both. Orthopedic surgery for scoliosis or kyphosis had been performed in 13 cases. Shunt revision was performed in 38 cases, myelolysis in 17, and decompression of the foramen magnum in 14 (28 %). After a mean follow-up of 1.9 years, syringomyelia decreased from 24 to 16 cases. There was a postoperative reduction of neck pain (one third), sensorimotor (two fifths), and cranial nerve deficits (one half). CSF flow at the foramen magnum did not change visibly after surgery. Ventricular size improved in about half of the patients. Slit-like ventricles were found in nine (6 pre-surgical) and enlarged ventricles in nine (23 pre-surgical). Complication rate was 6 % (3/50) per cases, and no patient died or deteriorated neurologically after surgery. CMII-related management guidelines are not well defined, since clinical constellations and presentations are varying. Often associated findings are syringomyelia, hydrocephalus, and scoliosis, and symptomatic CMII may be triggered by more than one underlying condition. According to literature and clinical experience, management recommendations can be defined. The most important finding is that hydrocephalus is often involved in symptomatic CMII and must always be considered first in any symptomatic patient. Intrinsic brain stem dysfunctions cannot be treated surgically, and monitoring of vital functions is sometimes the only clinical means that can be offered to the patient. Knowledge of the complex background has led to improved follow-up programs for the affected children and thus also improved longtime survival.