Spinal Intramedullary Arachnoid Cyst – a Rare Case or a Distinct Rare Entity?

Case Report

Austin Neurosurg Open Access. 2014;1(4): 1018.

Spinal Intramedullary Arachnoid Cyst – a Rare Case or a Distinct Rare Entity?

Manish Ranjan1*, Yasha TC2, Chandrajit Prasad3, Sampath S1 and Indira Devi B1

1Department of Neurosurgery, National Institute of Mental Health and Neurosciences, India

2Department of Neuropathology, National Institute of Mental Health and Neurosciences, India

3Department of Neuroradiology, National Institute of Mental Health and Neurosciences, India

*Corresponding author: Manish Ranjan, Department of Neurosurgery, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore 560029, India

Received: May 19, 2014; Accepted: July 31, 2014; Published: August 08, 2014

Abstract

Background: Spinal arachnoid cyst is a common cause of non-neoplastic spinal compressive myelopathy. Intramedullary arachnoid cyst is very unusual and rarely addressed in the literature.

Methods: We report the Clinico-pathological account of a thoracic intramedullary arachnoid cyst in an adult female with an unusual course of neurological recovery and present a review on spinal intramedullary arachnoid cyst.

Results: Fourteen cases of primary intramedullary cyst have been reported in the literature, mostly affecting the paediatric population. Only 5 cases have been reported in adults. Though rare, similar clinical experience from previous reported cases suggests that intramedullary arachnoid cyst really represent a distinct clinical entity. It should be considered in the differential diagnosis of cystic intramedullary lesions and merit incorporation into the existing classification of spinal arachnoid cyst.

Introduction

Arachnoid cysts are the commonest non-neoplastic causes of spinal cord compression [1-4]. They are more often encountered as incidental findings in examinations performed for other reasons [2]. Most of the arachnoid cysts are extradural in location, though it can be intradural [5,6]. We report clinicopathological detail of a rare case of thoracic intramedullary arachnoid cyst in an adult and review the literature of the spinal intramedullary arachnoid cyst.

Case Presentation

A 40-year-old lady presented with progressive weakness of both lower limbs since the last two months and was bed ridden for the last 15 days. She also developed urinary hesitancy and urgency in last 15 days.

On examination, the tone in the lower limbs was grossly increased. She was paraplegic and had graded sensory loss below L1. Posterior column sensations were impaired in lower limbs. There was extensor plantar response, and the reflexes in lower limbs were exaggerated. She also had bladder dysfunction. MRI of the spine revealed a well circumscribed, cystic non-enhancing intramedullary lesion at D11-12 (Figure 1a,b,c). The lesion was entirely intramedullary, hypointense on T1 and hyperintense on T2 without perilesional signal changes or syrinx formation (Figure 1c,d,e). She underwent laminotomy, midline myelotomy and partial excision of the cyst. At surgery there was focal bulge of the spinal cord. After performing the mid line myelotomy, cyst was identified one mm beneath the medullary tissue, containing clear fluid. The cyst wall was thin and translucent. The cyst was not under tension with no communication with the subarachnoid space nor was there an extramedullary component. The cyst was fenestrated and partially excised, as the cyst wall was adherent to the cord.