Tarlov
cysts
Tarlov cysts are cerebrospinal-fluid-filled dilations located around nerve roots, most often in the sacrum. Long considered simple anatomical curiosities, they can cause disabling pain in some patients. This page explains what these cysts are, how they are diagnosed, and the technique I developed to treat them.
Described in 1938 by American neurosurgeon Isadore Tarlov, these cysts (also known as perineural cysts or sacral meningeal cysts) are dilations of the nerve-root sheath filled with cerebrospinal fluid, the fluid surrounding the brain and spinal cord. They most commonly form in the sacrum, at the base of the spine.
They are common: a meta-analysis of more than 13,000 subjects found Tarlov cysts in approximately 4% of the general population, with a higher prevalence in Europe (about 6%) and in women [1][1] Klepinowski T, Orbik W, Sagan L. Global incidence of spinal perineural Tarlov's cysts and their morphological characteristics: a meta-analysis of 13,266 subjects. Surg Radiol Anat. 2021 Jun;43(6):855-863. doi: 10.1007/s00276-020-02644-y. PMID: 33452905., and some MRI series report up to 9% of cysts across the entire spine [2][2] Burdan F, Mocarska A, Janczarek M, Klepacz R, Łosicki M, Patyra K, Brodzik A, Kiszka J, Chruścicka A, Żelazowska-Cieślińska I, Starosławska E. Incidence of spinal perineurial (Tarlov) cysts among East-European patients. PLoS One. 2013 Aug 5;8(8):e71514. doi: 10.1371/journal.pone.0071514. PMID: 23936511. and 13% of sacral cysts in adults [3][3] Kuhn FP, Hammoud S, Lefèvre-Colau MM, Poiraudeau S, Feydy A. Prevalence of simple and complex sacral perineural Tarlov cysts in a French cohort of adults and children. J Neuroradiol. 2017 Feb;44(1):38-43. doi: 10.1016/j.neurad.2016.09.006. PMID: 27836653.. In the vast majority of cases, they are discovered incidentally on MRI and cause no symptoms; only a small minority ever become symptomatic. An asymptomatic cyst requires no treatment, only awareness that it is present.
In some patients, the cyst fills under the effect of cerebrospinal-fluid pulsations, enlarges, and eventually compresses nearby nerve roots. The most common signs are:
- pain in the sacrum and lower back, radiating to the buttocks, perineum, hips or legs;
- pain worsened by sitting, prolonged standing, coughing or Valsalva-type straining;
- burning, tingling or numbness in the distribution of the compressed nerve roots;
- in some cases, urinary, bowel or sexual dysfunction related to compression of the sacral nerve roots.
These often fluctuating symptoms can become profoundly disabling and affect professional, social and intimate life. Women are affected significantly more often than men.
Because these cysts are common and usually silent, many physicians have been taught not to attribute pain to them. As a result, patients whose MRI nevertheless shows large cysts may be told that their pain comes from somewhere else, or even that it is psychological. This diagnostic odyssey can last for years, and it is not uncommon for a patient to see five or six specialists before receiving an answer.
The reality is more nuanced: not all cysts cause pain, but some do. The purpose of a specialist consultation is to distinguish between them through rigorous analysis of the consistency between symptoms, clinical examination and imaging.
The assessment is based on three complementary examinations:
- lumbosacral MRI, the reference examination: it determines the location, size and number of cysts and their effect on the nerve roots;
- CT with bone windows, which looks for bone erosion adjacent to the cyst, a sign that it is progressing;
- assessment of whether or not the cyst communicates with the cerebrospinal-fluid spaces, which directly determines the choice of treatment.
Comparing these radiological findings with the symptoms and clinical examination makes it possible to determine whether the cyst is the probable cause of pain and which treatment may be appropriate.
Several techniques have been proposed to treat symptomatic Tarlov cysts. The scientific literature shows their limitations:
- Cerebrospinal-fluid drainage through a catheter: proposed in small series, with inconsistent results and complications specific to the implanted material (catheter displacement).
- CT-guided aspiration, alone or with injection of biological glue: simple aspiration is followed by recurrence of symptoms in most published series; glue injection relieves some patients (about two thirds) but carries a risk of recurrence and aseptic meningitis.
- Surgical excision of the cyst together with its nerve root, historically proposed by Tarlov himself: this is now considered too neurologically risky because the cyst wall may contain nerve fibers.
The technique I developed is based on the mechanism of the disease itself: weakness of the nerve-root sheath, which dilates under the pulsatile pressure of cerebrospinal fluid. It treats this cause without sacrificing the nerve root. I operate in three stages:
- I approach the sacrum through a limited laminectomy (opening of the bony lamina) that exposes the cyst;
- I aspirate the cyst with a fine needle: it empties and collapses, without widely opening its wall or coming into contact with the nerve fibers it may contain;
- I reinforce the weakened wall with a dural sleeve placed around the cyst, preventing it from refilling and enlarging again. This provides lasting decompression of the nerve roots.
I first described this technique in a scientific publication reporting a series of 20 operated patients: 80% of the patients in that series improved, with no postoperative neurological deterioration [4][4] Haouas MY, Khoulali M, En-Nhaili Z, El-Johani H, Rghioui M, Srour R. Traitement chirurgical des kystes de Tarlov sacrés : à propos de 20 cas. Pan Afr Med J. 2019 Jun 10;33:98. doi: 10.11604/pamj.2019.33.98.10760. PMID: 31489076; PMCID: PMC6711676.. I have refined it since then in one of the largest known patient series.
As with any surgery, results vary from one patient to another, particularly depending on how long the nerve has been compressed, and can never be guaranteed. During consultation, I explain the expected benefits and risks and recommend surgery only when the link between the cyst and the symptoms is considered probable.
The hospital stay is generally short. I see each patient again for follow-up, with an MRI to confirm that the cyst has collapsed. Symptom recovery is often gradual: nerve roots that have been compressed for a long time need time to recover, and some residual symptoms may persist when compression has lasted for years. This is one reason why early management, once the diagnosis is established, offers the best chance of recovery.
Frequently asked questions
No, in the vast majority of cases. An asymptomatic cyst discovered incidentally requires no treatment. Simple clinical monitoring is sufficient; seek medical advice if suggestive symptoms appear.
By assessing the consistency between three elements: your symptoms (their location, nature and worsening while sitting), the clinical examination, and imaging (MRI and CT). This is precisely the purpose of a specialist consultation.
No. Surgery is offered only for disabling symptoms that do not respond to medical treatment and when the link between the cyst and the pain is considered probable. In other cases, pain management remains the standard approach.
I approach the cyst through a limited opening, aspirate it with a fine needle to empty it, and then reinforce its wall with a synthetic dural sleeve to prevent it from dilating again. The technique is designed to be as minimally invasive as possible and to preserve nerve fibers.
As with any surgery involving nerve roots, risks include cerebrospinal-fluid leakage, infection, and temporary or persistent worsening of symptoms. These risks are explained during consultation and weighed against the expected benefit.
Most operated patients improve, but the result can never be guaranteed: nerves that have been compressed for a long time may retain residual damage. The earlier the condition is treated, the better the chances of recovery.