- Department of Neurosurgery, Oscar Super Speciality Hospital, Rohtak, Haryana, India,
- Department of Neurosurgery, Southmead Hospital, Bristol, United Kingdom,
- Department of Neurosurgery, University of Manitoba, Winnipeg, Manitoba, Canada,
- Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India.
Krishnakumar Kesavapisharady, Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India.
DOI:10.25259/SNI_525_2021Copyright: © 2021 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Vishal Vishnu Thakur1, Ranjit Devidas Rangnekar2, Shashank Aroor3, Krishnakumar Kesavapisharady4, Mathew Abraham4. Conus medullaris intramedullary arachnoid cyst- case report and review of the literature. 27-Jul-2021;12:370
How to cite this URL: Vishal Vishnu Thakur1, Ranjit Devidas Rangnekar2, Shashank Aroor3, Krishnakumar Kesavapisharady4, Mathew Abraham4. Conus medullaris intramedullary arachnoid cyst- case report and review of the literature. 27-Jul-2021;12:370. Available from: https://surgicalneurologyint.com/surgicalint-articles/11003/
Background: Spinal intramedullary cysts present a radiological dilemma. We present a rare case of a conus intramedullary arachnoid cyst and report on its differentiating features and management.
Case Description: We report a case of a 30-month-old child who presented with decreased gluteal sensation and urinary dribbling for 6 months. Apart from some slowness in walking, the power was normal in all four limbs. Imaging showed a non-enhancing, T2-weighted hyperintense 12 × 8 mm conus intramedullary cyst without any edema. A T12-L1 laminotomy followed by marsupialization of the cyst was done. Histopathology was suggestive of an arachnoid cyst. The postoperative course was uneventful with improvement in muscle strength and achievement of regular milestones. We also present the pertinent review of the literature to date.
Conclusion: Intramedullary arachnoid cysts are a rare entity and should form the differential diagnosis for cysts presenting in the conus medullaris. Simple decompressive options may suffice for symptomatic cases and radical excision may be avoided. A high index of suspicion is essential considering the subtle nature of presenting symptoms.
Keywords: Conus medullaris cyst, Intramedullary arachnoid cyst, Spinal arachnoid cyst
Intramedullary cystic lesions comprise a small subgroup of spinal lesions. Their radiological isolation is difficult due to common morphology. This makes choosing the correct surgical approach difficult. Usually, the diagnosis of the intramedullary cystic lesion is done on intraoperative or histopathological grounds.[
We present a 30-month-old male child with a normal perinatal history who was referred to our center with a history of decreased sensation over the gluteal region along with persistent dribbling of urine for 6 months. Neurological examination was normal, except for decreased perianal sensations. He was able to walk but at a slower pace than before; however, the exact power could not be graded due to the age factor limiting communication. Magnetic resonance imaging (MRI) of the spine showed a well-defined intramedullary cystic lesion of size 12 × 8 × 8 mm in the conus medullaris at the T12-L1 level, which was hypointense on T1-weighted images and hyperintense on T2-weighted images with no perilesional edema, solid component, or contrast enhancement [
The patient underwent T12-L1 laminotomy under intraoperative monitoring. After a midline durotomy, the cyst was seen surfacing near the midline covered by a thin layer of gliotic tissue. The cyst was opened at its most superficial point and clear fluid akin to cerebrospinal fluid was drained. Repeated Valsalva maneuver confirmed that the central canal was separate from the cyst. There was no definite plane of dissection between the conus and the cyst. The cyst was marsupialized by suturing its wall to the arachnoid of the cord to prevent reclosure [
Spinal arachnoid cysts are usually seen in extradural or intradural extramedullary locations; however, their intramedullary occurrence is rare. Reports of IMAC are few and to date, only 24 cases have been reported.[
Spinal arachnoid cysts are benign developmental cystic lesions. Their origin remains unclear; however, congenital, traumatic, and inflammatory causes have been postulated.[
According to our literature review including our case report [
Like in the previous reports, the dorsal cord is the most common site reported for IMAC in both the pediatric and adult age groups in our literature review as well.[
MRI with contrast is the investigation of choice for diagnosing IMAC. They are characterized by non-enhancing homogenous well-circumscribed cysts, hypointense on T1-weighted images, and hyperintense on T2-weighted images, without any surrounding edema. The radiological differential diagnosis for IMAC includes primary or secondary syrinx, epidermoid cyst, cystic astrocytoma, teratoma, ganglioglioma, dermoid, and meningomyelocele, cystic lesions such as neuroenteric, neuroglial, ependymal, and parasitic cysts.[
Treatment is reserved for symptomatic lesions. Management options range from percutaneous aspiration to surgical fenestration, myelotomy with partial or complete removal of cyst wall, or placement of cysto-subarachnoid shunt.[
In IMAC excising the cyst wall is usually difficult due to its adherence to the cord parenchyma. Radical excision can be circumvented with simple fenestration or decompression with marsupialization.[
On histopathology, the presence of arachnoid cells is the key for differentiating radiologically similar lesions such as ependymal and neurenteric cysts, which have ependymal and endodermal lining respectively, whereas neuroglial cysts have an absence of any arachnoid cells and tend to have a poor capsule.[
Although most reports emphasize surgery for symptomatic cases, Fonseca and Ratilal demonstrated that clinical observation can be done in mild or asymptomatic cases.[
Most of the operated cases show complete recovery on short-term follow-up along with radiologic resolution of the cyst on follow-up. However, radiologic recurrence of the cyst has been reported in two cases so far, with one of them becoming symptomatic. The reasons speculated for recurrence were incomplete excision of the cyst, an unnoticed ventral subarachnoid channel, postoperative adhesion, and fibrosis.[
IMACs are a rare entity and should form the differential diagnosis for cysts presenting in the conus medullaris. Simple decompressive surgical options for symptomatic lesions may suffice and radical excision may be avoided.
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