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|LETTER TO EDITOR
|Year : 2016 | Volume
| Issue : 6 | Page : 1335-1336
Spontaneous resolution of Chiari malformation and associated syringomyelia
Arun K Mazumder1, Sayan Das1, Prasad Krishnan2
1 Department of Radiodiagnosis, Peerless Hospital, Kolkata, West Bengal, India
2 Department of Neurosurgery, National Neurosciences Centre, Kolkata, West Bengal, India
|Date of Web Publication||11-Nov-2016|
Department of Neurosurgery, National Neurosciences Centre, Kolkata, West Bengal
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mazumder AK, Das S, Krishnan P. Spontaneous resolution of Chiari malformation and associated syringomyelia. Neurol India 2016;64:1335-6
The caudal displacement of the cerebellar tonsils below the level of the foramen magnum in the absence of spinal dysraphism, hydrocephalus, or encephalocele is called Chiari malformation More Details Type 1 (CM1). With the widespread use of magnetic resonance imaging (MRI) to evaluate children with headaches, seizures, or developmental delays, the number of patients diagnosed with asymptomatic CM1 is increasing.
A 5-year-old girl had one episode of generalized tonic clonic seizure for which an MRI study was carried out one day after the event. This revealed a CM1 with tonsillar descent extending below the C1 arch and a loculated syringomyelia present within the cervical and thoracic cord [Figure 1]a. There was neither any abnormality detected in the brain nor the presence of hydrocephalus. The family was advised surgery (foramen magnum decompression and duraplasty). On being informed that this would not cure the seizures and because the child was otherwise asymptomatic, they refused surgical intervention. The follow-up MRI done 1 year later showed near total resolution of the syringomyelia with ascent of the tonsil above the foramen magnum and visualization of the cerebrospinal fluid spaces in front of and behind the cervicomedullary junction [Figure 1]b.
|Figure 1: Sagittal T2-weighted magnetic resonance imaging scans showing (a) tonsillar descent below the level of the C1 arch with obliteration of the cerebrospinal fluid pathways, anterior and posterior to the cervicomedullary junction with the presence of a multiloculated cervical and dorsal syrinx; and, (b) the follow-up image with tonsil at the level of the foramen magnum and almost collapsed syrinx cavity|
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The variance of tonsillar position with age is a well-known phenomenon. Mikulis et al., described a trend towards tonsillar ascent with increasing age and advocated that upto 6mm descent of tonsils below the rim of foramen magnum in the 1st decade of life can be considered normal. In children, growth of the child and increase in size of the skull with concomitant increase in posterior fossa volume might cause the tonsils to revert to their normal position., In adults, cerebellar atrophy with increased infratentorial available space might cause the same phenomenon., Speculating on other causes of spontaneous regression of a CM1, Girard et al., reported 8 children who had this abnormality with vein of Galen aneurysmal malformation. Following therapeutic embolization, there was tonsillar ascent in 5 of these cases. They concluded that venous congestion of the posterior fossa might be responsible for the tonsillar descent and that the latter might resolve once this issue was addressed.
With regard to CM1 associated with syringomyelia, Santoro et al., described 2 patients who had spontaneous decompression of the syrinx into the spinal subarachnoid space. In one case, they were able to demonstrate a communication between the syrinx cavity and the spinal subarachnoid space and hypothesized that “fissuring of the cord parenchyma is instrumental in the spontaneous resolution of syringomyelia.” We could not demonstrate any such changes in our case, and this theory could not explain the restitution of the tonsils to their normal position, as was evident in the present case. Another case report  of a similar occurrence that occurred in a woman following normal vaginal delivery speculates the cause to be a rupture of the subarachnoid adhesions at the foramen magnum due to changes in the intraspinal and intracranial pressure brought on by labour. No such event occurred in our case.
Deniz and Oksüz  described an adult patient with seizures who was noted to be having syringomyelia which regressed with time. They speculated that raised intracranial pressure during the seizure episode might have predisposed to the syringomyelia, and that in the subsequent seizure free period, intracranial and intraspinal pressures might have stabilized leading to resolution of syringomyelia. This might have happened in our child, although in their case, unlike in ours, the tonsillar descent did not improve. Moreover, a syrinx of the size seen in our patient is unlikely to form over a day's time.
While the current consensus is that asymptomatic patients with CM1alone should not be offered surgery, the situation is different if there is associated syringomyelia. Schijman and Steinbok  reported from an international survey that 75% of neurosurgeons would operate on an asymptomatic patient with incidentally detected CM1 if there was an associated large syringomyelia (>8 mm in diameter). We follow the same protocol in our institute and had, hence, initially offered surgery to this child.
The conclusion from this case is that if both the CM1 and syringomyelia have the possibility of spontaneous resolution, the treatment strategy for asymptomatic Chiari patients with syringomyelia needs to be revisited. It is unclear if the size of the syringomyelia itself can be used as a factor to determine the need for surgery and how frequently would magnetic resonance imaging scans be required to detect an increase in the syrinx diameter and cord atrophy, which may often be very subtle. We do not contend that one must wait in the hope of spontaneous regression or that this is an expected event in the natural history of this entity, However, we would like to emphasize that offering an early surgery to patients with nonspecific complaints is often due to an overestimation of the true rate of neurological worsening in this disease.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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