A Hidden Condition: Multiple Tarlov Cysts Unveiled in a Young Woman Seeking Primary Care for Debilitating Low Back Pain

Background

Tarlov cysts, which are more accurately termed as perineural root sleeve cysts, were first discovered by Isadore Max Tarlov in 1938 when he incidentally found 5 cases during an autopsy [1]. According to Nabor’s classification [2], Tarlov cysts are classified as type-II meningeal cysts, defined as sacral extra-dural spinal meningeal cysts with spinal nerve root fibers, filled with cerebral spinal fluid (CSF), between the layers of the perineurium and endoneurium near the dorsal root ganglion, without any connection with the perineural subarachnoid space [2,3]. The cysts are frequently located in the spinal canal of the S1-S5 region [3,4].

Symptomatic Tarlov cysts are rare, as most cases are asymptomatic and are usually found incidentally [4,5]. A recent meta-analysis of 13 266 subjects found that the global pooled prevalence of Tarlov cysts was 4.2% [6]. It was less common in Asia, where the prevalence was 3.3% [6]. There was female predominance (5.8%), compared with male (3.0%) [6]. However, only 15.6% of those with Tarlov cysts were symptomatic [6]. Common clinical presentations include low back pain, radicular pain in the relevant dermatomal distribution, or motor weakness [7]. Rarely, the cysts can cause cauda equina syndrome or myelopathy if they are located above the conus medullaris [7].

In this case, we report a young woman with multiple Tarlov cysts presenting with severe low back pain. Tarlov cysts are rarely detected, especially in the primary care setting.

Case Report

A 23-year-old Malay woman, who was a final-year medical student, presented to a primary care clinic in September 2021 with severe low back pain and stiffness for 1 week. The pain was sudden in onset and it was located at the lumbosacral region. It started after prolonged sitting while playing board games with her siblings for almost 6 hours. She described the pain as severe, persistent, and dull-aching in nature, with a self-reported score of 8/10 using the Visual Analogue Scale (VAS). The pain was aggravated by movements such as bending down. The pain was not relieved by oral paracetamol (acetaminophen) or rest. Despite the pain, she was still able to ambulate unaided. However, she was unable to attend her clinical postings as she could not stand or walk for more than 10 minutes.

There were no associated symptoms such as neurological weakness, other joint pain, fever, or weight loss. There was no recent trauma or fall prior to the onset of the back pain. Her bowel and bladder were functioning normally. There was no family history of joint pain, joint deformity, or malignancy.

On examination, she was a young woman of medium build. Her weight was 70 kg, with a height of 1.69 m which gave a body mass index of 24.5 kg/m2. Her vital signs were normal and her gait was normal. Spine examination revealed no apparent deformity or swelling. Upon palpation, there was a tenderness of the para-vertebrae muscles at the L4/L5 lumbosacral region. However, no step deformity was felt. The range of motion of the spine was restricted due to severe pain and stiffness. Her lumbar flexion was limited to 20°, extension was at 5°, the right and left lateral flexions were limited to 10°, and rotation was limited to 0°. The low back pain was elicited upon lumbar flexion. The lumbar and sacral myotomes (L1-S3) were assessed with the patient lying supine. Her straight leg raising test was negative. Movements of the hips, knees, ankles, and intertarsal and metatarsophalangeal joints were all normal. Neurological examination of the lower limbs (tone, power, and reflexes) was normal bilaterally. Sensation of all the dermatomes, including L1 and S2, was intact.

Due to the sudden onset and severity of the pain, it was arranged for her to receive a plain radiograph of the lumbosacral spine. Apart from mechanical back pain, the differential diagnosis at the time was ankylosing spondylitis.

Figures 1 and 2 show the anteroposterior and lateral views of the lumbosacral region via plain radiograph. The right pedicle outline at the L4 and L5 levels appeared ill defined and sclerotic. However, the lumbar lordosis was preserved. The alignment, vertebral body heights, intervertebral disc spaces, and posterior elements were preserved and no fracture was seen. The radiologist’s impression at that stage was that the destruction and erosion of the right pedicle at the L4 and L5 levels may have been caused by infection or malignancy. Tuberculin skin test (Mantoux), plain chest radiograph, full blood count, and erythrocyte sedimentation rate were all done in view of this. The results were all normal. A lumbosacral MRI of the spine using gadolinium contrast was ordered by the primary care physician after discussing with the on-call orthopaedic surgeon, in view of the abnormal radiograph findings. This was done to rule out tuberculosis or malignancies of the lower lumbar spine such as osteoid osteoma or osteoblastoma.

The patient was prescribed celecoxib 200 mg twice a day for 1 week to relieve her pain. In view of the suspicious lesion seen on the plain radiograph, she was urgently referred to the orthopaedic surgeon to review her MRI within a week. She was also referred to the physiotherapist by the primary care physician for education on spine care, transcutaneous electrical nerve stimulation (TENS), and strengthening exercises. This included exercises targeting the muscles of the back extensors, lateral buttocks, trunk rotators, posterior buttocks, and oblique abdominals.

At the orthopaedic clinic, she was further assessed and examined. Her VAS pain score had improved to 4/10 with rest, regular analgesia, and physiotherapy. Her functional status and activities of daily living (ADL) were assessed using the Barthel Index score. She was unable to attend her clinical posting as she needed assistance with going up and down the stairs. She was otherwise independent in other ADL such as feeding, walking on a level surface, going to and from a toilet, continence of bowels and bladder, bathing, dressing, and grooming.

The lumbosacral MRI of the spine was reviewed by the orthopaedic surgeon at the orthopaedic clinic on the same day. The images are shown in Figures 3 and 4. The MRI revealed multiple Tarlov cysts in the spinal canal involving the descending nerve roots from the L5/S1 to the S2 levels. The contrasted lumbosacral MRI revealed multiple non-enhancing thin-walled CSF-intense perineural lesions (Tarlov cysts) in the spinal canal. The cysts were associated with the descending nerve roots from the L5/S1 to S2 levels bilaterally. The largest cyst measured 1.5 cm (anteroposterior)×1.3 cm (width)×2.0 cm (craniocaudal) and it was located at the S2 level. There was no spinal stenosis, nerve root impingement or disc displacement seen in any of the visualized levels. There was no abnormality seen on any of the pedicles, and there was no sign of osteoma or any other tumour seen on the MRI. She was informed about the diagnosis and prognosis by the orthopaedic spine surgeon.

She was followed up by the orthopaedic team after 2 weeks. Her VAS pain score has further improved to 2/10 with regular analgesia and physiotherapy. In view of this, she was continued on conservative management and regular follow up by the orthopaedic spine team every 6 months. She was informed that Tarlov cysts may increase in size and she may need surgical intervention if her symptoms worsen. A repeat MRI will be arranged if it is clinically indicated.

At the time of writing of this case report, the patient was receiving follow up care by her primary care physician. Her pain is well controlled with conservative management, with a VAS score of 1/10. It is not affecting her ADL anymore and she is able to attend her clinical posting. She has stated that she will inform the primary care physician if her symptoms worsen.

Discussion

This case highlights a rare cause of low back pain due to multiple Tarlov cysts in a young Malay woman. Although Tarlov cysts occur more commonly in women [4–6], they are rarely detected in the Asian population [6], especially during primary care consultation. Symptomatic Tarlov cysts are rare, with a reported incidence of approximately 1% [7,8]. The clinical presentation of symptomatic Tarlov cysts is non-specific, and it can be similar to other pathologies involving the disc and lumbosacral spine [7]. Typical clinical presentations include low back pain, sciatic radicular pain (sacral nerve root pain), coccyx pain, or perineal pain [8]. The onset of symptoms can occur suddenly or gradually, and it can be exacerbated by coughing or a change in position such as standing or bending down [9]. Red flag symptoms caused by compression of the caudal nerve root by the Tarlov cysts, such as lower limb weakness, neurogenic claudication, sensory changes across the gluteal area, perineal area, lower extremities, bowel and bladder dysfunction, vaginal or penile paraesthesia, and sexual dysfunction have also been reported [9,10].

Tarlov cysts are difficult to diagnose in the primary care setting because of limited knowledge about the condition and because many of the symptoms can mimic other, more common disorders. Most primary care physicians would not consider the possibility of Tarlov cysts in the differential diagnoses of patients presenting with low back pain, which is a common presentation in primary care. The key to diagnosing a potentially serious cause of severe low back pain during primary care consultation is by taking a systematic approach to diagnosis and management; ie, by taking a focused history and performing a thorough clinical examination looking for red flags in the presentation [11].

Low back pain can be classified into 4 broad categories: (i) non-specific/mechanical back pain, (ii) low back pain with radicular pain or neurogenic claudication, (iii) low back pain caused by a serious disorder affecting the spine, and (iv) low back pain caused by a different problem beyond the spine [11]. Non-specific low back pain, in which a specific pathoanatomic diagnosis cannot be identified, accounts for more than 90% of all low back pain seen in the primary care setting [11]. A longitudinal cohort study in the Australian primary care setting found that <1% of patients with low back pain had a serious pathological cause underlying their pain [12]. In the young woman in the present case study, a potentially serious cause of her severe low back pain could easily have been missed if a thorough history and physical examination had not been performed by the primary care physician. In this case, sudden-onset, severe, and persistent low back pain without any history of trauma is considered as a red flag that warrants further investigation.

Plain lumbosacral radiography was ordered in this case, in view of the persistent and severe pain which occurred suddenly, to exclude a potentially serious diagnosis such as ankylosing spondylitis. However, it is worthy to note that the majority of individuals who present with low back pain in primary care do not need diagnostic imaging [11]. Imaging is indicated only when a potentially serious cause of low back pain is suspected [11,12]. The combination of clinical symptoms, the intensity of the clinical suspicion, and the implications of a delayed diagnosis should all be taken into account when deciding whether to pursue further diagnostic testing and imaging [11,12]. A plain radiograph is a normal approach in many cases of Tarlov cysts [13]. Radiography may, however, demonstrate typical bone destruction in the spinal canal or anterior or posterior neural foramina as the cysts are usually multiple and extend around the circumference of the nerve, and can enlarge to compress neighbouring nerve roots and cause significant bone erosions [14]. In the present case, the plain lumbosacral radiograph showed sclerosis and bone erosion of the right pedicle at the L4 and L5 levels, a finding that can also be caused by infection or malignancy. Common infections in the Asian population, such as tuberculosis, were excluded, and baseline haematological work-ups were found to be normal in this case. MRI was ordered by the primary care physician in view of the suspicious radiograph. This patient was then urgently referred to the orthopaedic surgeon to review the MRI and for further assessment.

MRI is the imaging modality of choice to diagnose Tarlov cysts as it provides significantly greater soft tissue contrast [13]. In our patient, the MRI confirmed that she had multiple Tarlov cysts in the spinal canal involving the descending nerve roots from the L5/S1 to the S2 levels, bilaterally. Multiple Tarlov cysts are even more uncommon than single cysts [6,8]. A recent study proposed the concept of one ‘dominant’ cyst when there are multiple Tarlov cysts [13]. In the present case, the dominant cyst was located at the S2 level. According to the literature, the vast majority of Tarlov cysts have been found to be located at the S2/S3 level [6,13]. While it has been suggested that a larger Tarlov cyst may result in more severe symptoms [15], there is no published study that has established an association between the size and number of cysts in larger cohorts.

The pathogenesis of Tarlov cysts is unclear. In his published article in 1970, Tarlov suggested that trauma could be a potential aetiology for the perineural cysts, as 4 out of 7 of his patients had a history of trauma [3]. Tarlov proposed that haemorrhage into the subarachnoid space can result in a buildup of red cells, which then impedes the drainage of veins in the perineurium and epineurium, leading to rupture and subsequent formation of cysts [3]. However, Fortuna et al thought that the perineural cysts were congenital in origin, caused by arachnoid proliferations within the root sleeve, as the majority of the patients in their study did not have a history of trauma [16]. In the present case report, the young woman did not recall any history of trauma prior to the onset of the severe low back pain.

The treatment modality for Tarlov cysts ranges from conservative management (with analgesia, regular follow up, and imaging) to surgical management [17]. In the present case, the patient’s pain improved with analgesia, physiotherapy, and TENS. It was no longer affecting her ADL and she was able to attend her clinical post. She therefore continued with conservative management under the follow up of the orthopaedic team and the primary care physician. Tarlov cysts may increase in size and the need for surgical intervention may arise if the symptoms worsen [17]. However, there is little evidence on which surgical management is most effective or when it is indicated for symptomatic Tarlov cysts [18]. Historically, open surgical interventions have caused significant patient morbidity, particularly postoperative CSF leaks and infection [17,18]. More recently, CT-guided percutaneous aspiration has been proposed as an important prognostic procedure to identify patients for whom surgery might be beneficial [19]. Over the past decades, various surgical interventions with variable success rates have been described, including conservative or minimally invasive methods [20,21], cyst fenestration [22], and micro-surgical cyst excision [23]. A recent study found that microsurgical cyst fenestration was a safe and effective treatment for symptom relief in patients with Tarlov cysts [17]. When this microsurgical procedure was performed in 17 patients, 16 patients showed clinical improvement at long-term follow up [17]. More evidence is needed to establish which surgical modality is the most effective.

With or without surgery, patients with symptomatic Tarlov cysts need long-term follow up by orthopaedic surgeons and primary care physicians, so that early intervention can be considered if the symptoms worsen. Close monitoring and early surgical intervention are vital to prevent irreversible nerve damage, which can potentially be caused by Tarlov cysts.

Conclusions

This case highlights a rare origin of low back pain in a young woman which was caused by multiple Tarlov cysts. The clinical presentation of this condition mimics many other common disorders, making it difficult to diagnose in primary care. A systematic approach to identifying red flags in patients presenting with severe low back pain is the key to diagnosing a potentially serious cause for this common presentation in primary care. In this young woman, a potentially serious cause of her low back pain could easily have been missed if a thorough history and physical examinations were not performed by the primary care physician. The diagnosis of Tarlov cysts was confirmed by MRI in this case, which is the imaging modality of choice. This patient was managed conservatively as her symptoms and ADL improved with conservative management. However, she needs regular follow up and close monitoring so that early surgical intervention can be considered if her symptoms worsen, to prevent potentially serious complications caused by the Tarlov cysts.