What is Tarlov disease?

What is Tarlov Disease?

Tarlov disease, also known as perineural cyst disease or Tarlov cyst syndrome, is a rare neurological disorder characterized by cerebrospinal fluid-filled cysts that form within the nerve root sheaths, most commonly in the sacral spine between the perineurium and endoneurium near the dorsal root ganglion 1, 2.

Anatomical Location and Pathophysiology

Tarlov cysts develop where cerebrospinal fluid extends distally into the sensory nerve root sleeves and accumulates pathologically 3. These cysts:

• Occur most frequently at sacral spine levels (S2-S4), where nerve roots experience the highest hydrostatic pressure and lack protective vertebral foramina 3
• Form as meningeal dilations of the posterior spinal nerve root sheath 4
• Can communicate with the spinal subarachnoid space, enlarging via net inflow of cerebrospinal fluid 4
• May contain nerve fibers (75% of cases), ganglion cells (25%), and evidence of old hemorrhage (50%) on histopathological examination 5

Clinical Presentation

Most Tarlov cysts are asymptomatic and discovered incidentally on imaging 1, 6. However, when symptomatic, they cause:

Primary Symptoms:

• Sacropelvic dermatomal neuropathic pain - lower back pain and sacral radiculopathy 1, 3
• Bladder, bowel, and sexual dysfunction - including urinary incontinence, dyspareunia 1, 2
• Perineal pain - reported in almost all symptomatic patients 1

Progressive Neurological Deficits:

• Muscle atrophy and weakness from ventral motor root compression 3
• Cauda equina syndrome when multiple cysts or multiroot compression occurs 6, 3
• Radiculopathy affecting lower extremities 2

Epidemiology and Risk Factors

• 90% of patients are women 3
• Genetic connective tissue disorders, particularly Ehlers-Danlos syndrome, convey considerable risk 3
• Positive family history documented in some cases suggests possible genetic inheritance 1

Pathogenesis

The exact pathogenesis remains unclear, but proposed mechanisms include 2, 5:

• Increased hydrostatic pressure within nerve root sheaths
• History of trauma
• Old hemorrhage
• Congenital factors
• Iatrogenic causes

Diagnostic Approach

Magnetic resonance imaging is the gold standard for diagnosis 2. The diagnostic workup includes:

• MRI of lumbosacral spine - identifies cyst location, size, and relationship to neural structures 7, 1
• CT myelography - demonstrates communication with spinal subarachnoid space and delayed filling of cysts 4, 5
• Clinical correlation - complete neurological examination, electromyography in selected cases 1

Key Imaging Features:

Tarlov cysts appear as deep cystic masses communicating with sacral foramina on ultrasound 8. On MRI, they are identified in the sacral region with characteristic nerve root involvement 9, 7.

Important Clinical Caveat:

Surgeons must be aware of Tarlov cysts prior to sacral debridement procedures, as inadvertent leakage of cerebrospinal fluid can lead to meningitis 9. Pelvic extension of Tarlov cysts can mimic adnexal masses on ultrasound, making MRI mandatory before gynecologic surgery when cystic pelvic lesions coexist with radicular pain or sitting intolerance 10.

Treatment Considerations

Asymptomatic Tarlov cysts do not require treatment and should be followed conservatively 4, 5, 3. Even incidental findings should be documented in case symptoms develop later 3.

Surgical Indications:

Surgery is considered for symptomatic cysts, particularly when:

• Cysts larger than 1.5 cm in diameter producing radicular pain or bladder/bowel dysfunction show excellent surgical outcomes (70% complete or substantial symptom resolution) 5
• Disabling symptoms require intervention 3
• Progressive neurological deterioration occurs 10

Surgical Techniques:

• Cyst-wrapping surgery appears to offer the best long-term outcomes by permanently reducing cyst size and reconstructing nerve root sleeves 3
• Sacral laminectomy with cyst fenestration and partial cyst wall resection 6, 4
• Myofascial flap repair and closure 4

Poor Surgical Outcomes:

Cysts smaller than 1.5 cm producing nonradicular pain show minimal improvement with surgery (0% significant improvement in one series) 5.

Prognosis

With appropriate surgical intervention for symptomatic large cysts, 70% of patients achieve complete or substantial symptom resolution with average follow-up of 31.7 months 5. Cyst-wrapping surgery may promote axonal regeneration and improve somatic and autonomic sacral nerve function 3.