Fig 3. Postoperative MRI LS spine (blue arrow)
Conclusion and results
Although most Tarlov cysts are asymptomatic, patients with symptoms may need surgical intervention. Laminectomy with cyst fenestration and plugging with augmentation by glue can be an appropriate method to achieve desirable results.
As on follow-up after 3 months, the patient has a remarkable improvement in bladder and bowel symptoms as well as his back pain. MRI of the lumbosacral spine was repeated postoperatively which showed resolution of the cyst.
Discussion
First described by Isadore M. Tarlov in 1938, the perineural cyst is a rare anomaly found at the level of the spinal ganglion and filled with cerebrospinal fluid but without communication with the perineurial subarachnoid space[5]. Nebors classified the Tarlov cyst as a type II meningeal cyst, which is a sacral extradural spinal cyst with spinal nerve roots filled with cerebrospinal fluid(CSF)[6]. In the general Asian population, Tarlov cyst has a prevalence of 3.3%.[7] The global pooled prevalence, as shown by a recent meta-analysis, was 4.2% and there was female predominance as compared to male[8].
The pathogenesis of the Tarlov cyst is unknown. Trauma is suggested as a potential etiology by Tarlov in his study[9]. According to Tarlov, hemorrhage in subarachnoid space led to the build-up of red cells, impeding venous drainage of perineurium and epineurium, leading to cyst formation. Fortuna et al. reported perineural cysts were congenital in origin [10]. The mechanism by which the Tarlov cyst produces clinical symptoms is a topic of debate. Ball valve theory is the most popular theory to explain. It is believed that defects in the perineural sheath act as one-way valve and thus allow CSF to accumulate and be trapped within the cyst.[11]
The origin of the perineural cyst is in between the endoneurium derived from the pia matter and the perineurium derived from arachnoidal matter. Although cysts can be found anywhere in the spine, they are more common in the sacral spine [12]. They are found along the nerve roots, at or distal to the junction of the posterior root and the dorsal ganglion[9]. While most Tarlov cysts are found incidentally during MRI imaging, symptomatic Tarlov cysts are rare, with a reported incidence of 1%[11]. The clinical presentation of Tarlov cyst is non-specific and mimics pathologies of the disc and lumbosacral spines, such as sciatica, sacral or buttock pain, vaginal or penile paresthesia or sensory changes over the buttocks, perineal area, and lower extremity. [11] Our patient had back pain as well as bladder and bowel symptoms requiring surgical management.
MRI is the investigation of choice to diagnose the Tarlov cyst as it provides soft tissue contrast. Tarlov’s cyst was confirmed in our case after getting an MRI scan.
The initial treatment option for symptomatic Tarlov cyst is conservative with analgesia and regular follow-up. However, if symptoms persist, intervention is required. Invasive techniques include computer tomography (CT) guided aspiration, sacral laminectomy, and cyst fenestration, resection, or imbrication. One study found that microsurgical cyst fenestration was a safe and effective treatment[13]. However, surgical intervention may be associated with CSF leak and infection[14]. In view of a large cyst presenting with urinary symptoms, our patient was managed surgically with cyst fenestration and plugging.