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.