C hiari malformations constitute a group of entities with very different etiologies, clinical features, and pathophysiologies. 2 , 5 , 8 , 11 , 14–16 Little in the literature, however, has focused on patients who develop an acquired Chiari-like syndrome with its attendant syringomyelia as a complication of previous posterior fossa pathological entities. Likewise, while hydrocephalus and its various treatments have been widely discussed in the neurosurgical tome, nonneoplastic brainstem hypertrophy as a consequence of sustained elevated intracranial
Rohan Ramakrishna, Jeffrey C. Mai, Tanya Filardi, Samuel R. Browd and Richard G. Ellenbogen
Richard G. Ellenbogen, Rocco A. Armonda, Dennis W. W. Shaw and H. Richard Winn
In patients with Chiari I malformation with and without associated syringomyelia, aberrant cerebrospinal fluid (CSF) dynamics and a spectrum of posterior fossa pathological findings are demonstrated. In this study, the authors test the validity of using prospective cardiac-gated phase-contrast cine-mode magnetic resonance (MR) imaging to define the malformation, delineate its pathophysiology, and assist in implementing a rational treatment plan.
Eighty-five cases were prospectively analyzed using cine MR imaging. Sixty-five patients, adults and children, with symptomatic Chiari malformation, with and without syringomyelia, were surgically treated from 1990 to 1999. All patients underwent pre- and postoperative cine MR evaluation. Ten patients were treated after a previous surgical procedure had failed. To establish CSF flow characteristics and normative CSF profiles, 20 healthy volunteers were examined.
Compared with normal volunteers, in Chiari I malformation patients with and without syringomyelia, uniformly abnormal craniocervical junction CSF flow profiles were revealed. After intradural exploration, nearly all patients with Chiari I malformation experienced clinical improvement and CSF flow profiles, paralleling those of normal volunteers, were shown. In all patients in whom treatment had failed, abnormal preoperative CSF flow profiles, which correlated with suspected physiological abnormalities and the pathological findings noted at reoperation, were demonstrated.
Symptomatic Chiari I malformation is a dynamic process characterized by the impaction of the hindbrain in an abnormal posterior fossa. This compression obstructs the normal venting of CSF in and out of the craniocervical sub-arachnoid space, throughout the cardiac cycle. Therefore, decompression or enlargement of the posterior fossa to establish normal CSF pathways should be the primary goal of surgical intervention. Aberrant CSF flow appears to be only one aspect of the pathological condition found in patients with Chiari I malformation. Arachnoid scarring in the posterior fossa and selective vulnerability of the spinal cord may also be factors in the pathogenesis and maintenance of associated syringomyelia. Phase-contrast cine MR imaging is a useful tool in defining physiological and anatomical problems in patients with Chiari I and syringomyelia, and it can help guide an appropriate primary or salvage surgical therapy.
Ali H. Mesiwala, Christopher I. Shaffrey, Joseph S. Gruss and Richard G. Ellenbogen
2 -weighted image demonstrating upward invagination of the odontoid process into the clivus and no evidence of a hindbrain herniation or syrinx. B: A T 1 -weighted image obtained 3 years later, revealing the intervening development of Chiari I malformation and a cervical syrinx. Note the reduced height of the supraocciput, increased slope of the tentorium, and hypoplastic clivus. Based on these findings, the progressive tonsillar descent and development of syringomyelia were believed to be the most urgent symptomatic and pathophysiological issues to be
Michael R. Levitt, Toba N. Niazi, Richard A. Hopper, Richard G. Ellenbogen and Jeffrey G. Ojemann
83 : 575 – 582 , 1995 10 Cinalli G , Spennato P , Sainte-Rose C , Arnaud E , Aliberti F , Brunelle F , : Chiari malformation in craniosynostosis . Childs Nerv Syst 21 : 889 – 901 , 2005 11 Coppa ND , Kim HJ , McGrail KM : Spontaneous resolution of syringomyelia and Chiari malformation Type I in a patient with cerebrospinal fluid otorrhea. Case report . J Neurosurg 105 : 769 – 771 , 2006 12 de Jong T , Bannink N , Bredero-Boelhouwer HH , van Veelen ML , Bartels MC , Hoeve LJ , : Long-term functional
Taylor J. Abel, Abhineet Chowdhary, Patrik Gabikian, Richard G. Ellenbogen and Anthony M. Avellino
. Basilar impression associated with CM-I is therefore the result of reversed cervical growth and ascending nerve roots. In a related study, Royo-Salvador and associates 10 published a report of 20 patients treated for fatty terminal filum. Two of these patients presented with isolated Chiari malformations and five presented with a combination of scoliosis, syringomyelia, and Chiari malformation. Fifty percent of the fila transected in this study manifested a lack of elasticity intraoperatively. All 20 patients experienced relief from their clinical symptoms after