Abnormal gas myelogram
Milosh Perovitch in Radiological Evaluation of the Spinal Cord, 2019
Hydromyelia is a congenital dilatation of the central canal that can have the form of a narrow slit often found in necropsies, but it can also present a fairly large tubular cavity involving several segments, or even most of the length of the spinal cord. Hydromyelus can be associated with the spina bifida occulta, meningomyelocele, diaste-matomyelia, and Arnold-Chiari malformation. Thus, hydromyelia is linked to developmental malformations of the neural tube.59 Larger cavities in hydromyelia sometimes have the shape similar to the fetal canal.58 Hydromyelus is lined with epen-dymal cells; however, the ependymal lining may be incomplete at the margin of the cavity and replaced by thickened subependymal neuroglia that will extend into the cavity in the form of granulations. The direct connection between the hydromyelus and the central canal, as well as the fact that it is mostly lined with ependymal cells, differentiates this cavitation from primary or secondary syringomyelia or hematomyelia.58 Gas myelography, in the cases we had the chance to observe, showed a smooth widening of a shorter segment of the cervical spinal cord. Onl the sagittal diameter of the spinal cord was altered, whereas the transverse diameter remained within the upper normal limits. Changes of the position of the table with the patient in the right decubitus did not apparently influence the shape of the enlarged spinal cord, nor could we detect signs of spinal cord atrophy above or below the widening (Figure 4).
Revision suboccipital decompression for complex Chiari malformation
Gregory D. Schroeder, Ali A. Baaj, Alexander R. Vaccaro in Revision Spine Surgery, 2019
The Chiari malformations are a diverse group of anomalies in which a mismatch between the posterior fossa neural and bony elements may result in a relative descent of the cerebellar tonsils through the foramen magnum. This may lead to dorsal compression of the brainstem and disturbance of normal cerebrospinal fluid (CSF) circulation. Patients can present with a variety of symptoms, including but not limited to exertionally induced occipital headaches, neck pain, dysphagia, sleep apnea, dysmetria, and paraesthesia. Hydrocephalus and spinal cord syringomyelia can also develop, which can result in further neurologic deficits and lead to myelopathy and scoliosis. For patients in whom clinical and radiographic criteria are met, suboccipital decompression is an option to palliate symptoms or address syringomyelia or a combination of interdependent neurologic findings. A decompression of the foramen magnum, often paired with a C1 laminectomy and duraplasty, is the standard procedure offered, although many variations in surgical technique exist (Figure 10.1).
Case 2.11
Monica Fawzy in Plastic Surgery Vivas for the FRCS(Plast), 2023
A Chiari 1 malformation occurs when the one or both cerebellar tonsils descend through the foramen magnum. Treatment should be considered if symptomatic or associated with a syringomyelia. In children with raised ICP due to cephalocranial disproportion, teams may often consider posterior vault expansion, and if this is not successful, then progress to a foramen magnum decompression.
Congenital Spinal Lipomatous Malformations. Part 2. Differentiation from Selected Closed Spinal Malformations
Published in Fetal and Pediatric Pathology, 2021
A terminal myelocystocele is in part a hydromyelic cyst of variable size formed by the retained terminus of the medullary spinal cord, the area probably including but not limited to the embryonic terminal ventricle. Hydromyelia is an enlargement of the central canal of the spinal cord. As a developmental lesion, isolated hydromyelia is usually asymptomatic in a newborn, although hydromyelia may be part of a more complex malformation. When hydromyelia is a prominent enlargement of the central canal, often in the lumbar spinal cord, the term hydromyelic cyst has been used, mostly by radiologists. Hydromyelic cysts cannot become very large within the confines of a normal spinal canal. They are not pressure lesions like a syrinx, so the spinal tracts simply bend around these innocuous cysts within the otherwise intact spinal cord [28]. On the other hand, formation of a terminal myelocystocele is outside the spinal canal due to a widely bifid lower spine that allows the caudal spinal cord to expand into a large, fluctuant, subcutaneous malformation. The enlargement in this malformation is of the terminal spinal cord wherein the central canal becomes geatly expanded and there is a tight adhesion of the neural tissue wall of this “hydromyelic cyst” to overlying skin (Figure 24).
Association between subarachnoid hemorrhage-induced hydrocephalus and hydromyelia: pathophysiological changes developed in an experimental model
Published in Neurological Research, 2023
The model used in this study is a modification of the kaolin-induced hydrocephalus model described by Becker et al. [27]. However, numerous studies failed to demonstrate a patent anatomical pathway between the 4th ventricle and the central channel in humans [2,8]. Whereas the central channel obliterates in humans with increasing age, it remains patent in rabbits and other animals [3,6,13,18,19,21,26,27]. In humans, the central channel does not enlarge in the course of obstructive hydrocephalus with very rare exceptions [2,28]. Therefore, the validity of experimental models inducing hydromyelia by obstructive hydrocephalus has been questioned [28]. In future research, it will be helpful if the radiological scans (CT and/or MRI) support both hydrocephalus and hydromyelia in the SAH group. Besides, the neurological functions of animals in all groups should be evaluated by an independent researcher to perform an objective between-group comparison regarding the neurological deficits and to understand the consequences of the early brain injury caused by SAH. Further animal experiments should include better representative SAH models of both posterior and anterior circulations.
Abrupt foramen magnum syndrome due to shunt malfunction in a previously asymptomatic chiari I malformation: the hidden predictable risk in long-lasting shunted patients
Published in British Journal of Neurosurgery, 2023
Federica Novegno, Andrea Pagano, Filippo Fava, Giuseppe Umana, Pierpaolo Lunardi, Mario Francesco Fraioli
Hydrocephalus accounts for only 7-10% of the CIM cases; thus, its occurrence may be the result of impaired CSF circulation at the level of the 4th ventricle outlets, hypothesizing that the tonsillar herniation alone may induce only a partial obstruction of the Magendy foramen.16 Moreover, the presence of hydrocephalus is supposed to be involved in the appearance of syringomyelia, due to an increase of the differential pressure above and below the subarachnoid obstruction at the foramen magnum, leading to a disruption of the spinal cord barrier. Data from the literature demonstrated that syringomyelia responded better than CIM after ETV procedures.16,17 According to the authors, the treatment of hydrocephalus is effective in resolving the symptoms of CIM and syringomyelia in those patients without an overcrowded posterior cranial fossa on volumetric measurements and with a cystic 4th ventricle.
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