Understanding of the Chiari malformation type I (CMI) has evolved over time thanks to accumulated surgical experiences, neuroradiological refinements, and better comprehension of pathophysiology. CMI is defined as a descent of the cerebellar tonsils into the cervical canal due to a volumetric disproportion between the posterior fossa and cerebellar volumes. In more than one-third of cases, CMI is associated with syringomyelia, a cystic dilation of the spinal cord which leads to debilitating myelopathy. It has been demonstrated that both these conditions are associated with the obstruction of the cerebrospinal fluid flow at the level of the foramen magnum caused by the low-lying tonsils. Historically, different surgical approaches have been attempted to cure this condition, accounting for nearly 15 different surgical procedures. Nowadays, the most performed surgical procedure is the osteo-dural decompression of the posterior cranial fossa aimed to re-establish a free flow of CSF from the cranium to the spinal subarachnoid space. Although comprised of the spectrum of rare diseases, the diagnosis of CMI has strongly increased due to the large availability of MR scanners. While there is general acknowledgment that CMI is characterized by cerebellar tonsillar descent, an exhaustive and definitive definition of the illness is hardly available. As a consequence, patients with low-lying cerebellar tonsils can be labeled as CMI patients although often they are asymptomatic or present symptoms not strictly related to the CMI. Apart from imaging criteria, to make a diagnosis of CMI, it is imperative to discern if patient’s symptoms are related to the CMI. Unfortunately, symptoms vary widely and can often mimic or overlap other conditions. Similarly, tonsillar ectopia can also be associated with other developmental and acquired disorders (e.g., craniofacial syndromes, hydrocephalus, posterior fossa tumors, benign intracranial hypertension, cranio-cervical malformations) which must be ruled out. A correct clinico-radiological correlation is fundamental in modern management of CMI because it not only impacts on patient’s selection but also on an adequate surgical treatment to be offered. This chapter gives an ample overview on the most important clinical and radiological correlates of CMI showing modern pathophysiology bases, peculiarities, and pitfalls in diagnosis. Surgical approaches will be deeply explored through the analysis of surgical cases giving special emphasis to operative techniques, operative risks, complications avoidance, advanced neurosurgical procedures, and treatment efficacy. At the end, this chapter should be useful to both the novice reader, by reporting the most up-to-date information on the CMI, and to the expert surgeon by disclosing some debated surgical and clinical aspects.
Management of chiari malformation
Spena G.;Fontanella M. M.
2019-01-01
Abstract
Understanding of the Chiari malformation type I (CMI) has evolved over time thanks to accumulated surgical experiences, neuroradiological refinements, and better comprehension of pathophysiology. CMI is defined as a descent of the cerebellar tonsils into the cervical canal due to a volumetric disproportion between the posterior fossa and cerebellar volumes. In more than one-third of cases, CMI is associated with syringomyelia, a cystic dilation of the spinal cord which leads to debilitating myelopathy. It has been demonstrated that both these conditions are associated with the obstruction of the cerebrospinal fluid flow at the level of the foramen magnum caused by the low-lying tonsils. Historically, different surgical approaches have been attempted to cure this condition, accounting for nearly 15 different surgical procedures. Nowadays, the most performed surgical procedure is the osteo-dural decompression of the posterior cranial fossa aimed to re-establish a free flow of CSF from the cranium to the spinal subarachnoid space. Although comprised of the spectrum of rare diseases, the diagnosis of CMI has strongly increased due to the large availability of MR scanners. While there is general acknowledgment that CMI is characterized by cerebellar tonsillar descent, an exhaustive and definitive definition of the illness is hardly available. As a consequence, patients with low-lying cerebellar tonsils can be labeled as CMI patients although often they are asymptomatic or present symptoms not strictly related to the CMI. Apart from imaging criteria, to make a diagnosis of CMI, it is imperative to discern if patient’s symptoms are related to the CMI. Unfortunately, symptoms vary widely and can often mimic or overlap other conditions. Similarly, tonsillar ectopia can also be associated with other developmental and acquired disorders (e.g., craniofacial syndromes, hydrocephalus, posterior fossa tumors, benign intracranial hypertension, cranio-cervical malformations) which must be ruled out. A correct clinico-radiological correlation is fundamental in modern management of CMI because it not only impacts on patient’s selection but also on an adequate surgical treatment to be offered. This chapter gives an ample overview on the most important clinical and radiological correlates of CMI showing modern pathophysiology bases, peculiarities, and pitfalls in diagnosis. Surgical approaches will be deeply explored through the analysis of surgical cases giving special emphasis to operative techniques, operative risks, complications avoidance, advanced neurosurgical procedures, and treatment efficacy. At the end, this chapter should be useful to both the novice reader, by reporting the most up-to-date information on the CMI, and to the expert surgeon by disclosing some debated surgical and clinical aspects.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
