ENDOMETRIOSIS OF THE SCIATIC NERVE AND OF THE SACRAL PLEXUS

- two different diseases with same name but with different symptoms and different treatments -

SUMMARY

Sciatic nerve endometriosis (SNE) and sacral plexus endometriosis (SPE) are rare, distinct conditions impacting the pelvic nerves, each with unique clinical characteristics and requiring specialized treatment approaches. While SNE involves the sciatic nerve and is more aggressive, SPE affects the sacral plexus and is typically a secondary extension from pelvic organ endometriosis.

• Sciatic Nerve Endometriosisis an aggressive condition developing primarily within the intrapelvic portion of the sciatic nerve. Symptoms may include cyclical sciatica, neurological impairments in the lower limb, and foot drop. Diagnosing SNE requires a neuropelveological approach, combining detailed patient history, physical examination, and advanced imaging like MRI. Surgery for SNE is highly complex and considered a "one-shot" operation due to the risks associated with vascular and nerve injury. Only experienced surgeons in laparoscopic nerve surgery, like Prof. Possover, who pioneered these techniques, can effectively manage SNE.
• Sacral Plexus Endometriosisoften originates from genital endometriosis spreading to the sacral nerves, resulting in cyclical back pain, bladder sensitivity, and chronic constipation. Although SPE is less destructive than SNE, diagnosis and treatment remain challenging due to its rarity and overlapping symptoms with other conditions.

Both conditions are prone to misdiagnosis as common issues like lumbar disc herniation. Timely diagnosis and specialized surgical intervention are essential to prevent irreversible nerve damage and maintain quality of life.

1. Understanding the Difference Between the Sciatic Nerve and the Sacral Plexus

The sciatic nerve and the sacral plexus are both important structures in the pelvic cavity that help control movement of the legs, storage anmd voiding functions of the pelvic organs and sensation. However, they have different roles and locations in the body.

What is the Sacral Plexus?

The sacral plexus is a network of nerves located in the pelvis. This "nerve network" is made up of nerve fibers coming from the lower part of your spinal cord. These nerves combine to form several branches that go to different parts of the pelvis, thighs, legs, and feet. Think of the sacral plexus as a “control center” that coordinates signals for various muscles and skin areas in your lower body.

What is the Sciatic Nerve?

The sciatic nerve is the largest nerve in the body, formed by nerves from the sacral plexus. It originates from this plexus and then travels down through your pelvis and into your leg. The sciatic nerve provides sensation to the skin of your leg and foot and controls several muscles in your lower leg, helping with movement like walking, running, and climbing.

Key Differences

• Location: The sacral plexus is in the pelvis close to the pelvic organs and can be affected by endometriosis extending from the uterus. In contrary, the sciatic nerve is far away from the uterus; endometriosis usually starts to develop directly at/in the sciatic nerve independently from any further endometriosis lesion within the pelvic cavity. Therefore endopmetriosis of the sciatic nerve (ESN) and sacral plexus endometriosis (SPE) both have the same name, but are completely different: SPE is an gynecological disease while ESN is a neurological disease.
• Function: The sacral plexus is a network that organizes and combines nerve signals from the pelvic organs, while the sciatic nerve is a single, large nerve that carries signals from and to the leg and foot.
• Structure: The sacral plexus is a complex "hub" of multiple nerves (sacral nerves) that eventually form the sciatic nerve, among others. The sciatic nerve is one of the final “branches” that arises from this hub. The pudendal nerve is another one.

Understanding these structures is important because issues affecting the sacral plexus can impact a larger area, while problems with the sciatic nerve generally cause symptoms in the leg. Both are essential for movement, sensation, and overall function of your lower body. Both endometrioses are not similar in the aggressivity: ESN is extremely destructive while SPE preserves very long time the integrity of the nerves.

2. Prevalence and incidence of the Sciatic Nerve and the Sacral Plexus

• Sciatic Nerve Endometriosis:The recognition of SNE as a distinct clinical entity began to gain traction in the latter part of the 20th century, although it had likely been an underdiagnosed condition for many years. A review published in 2019 identified 40 cases of extrapelvic sciatic endometriosis( Robert J. Trager, Sarah E. Prosak, Kelle A Leonard, Jessica E. Sigel, Jeffery A. Dusek. Diagnosis and Manmagement of Sciatic Endometriosis at the Greater sciatic foramen: a case report. Medicine, 2021;3:1816-1822). Traditionally, endometriosis was thought to primarily affect the pelvic organs, but over time, as more advanced laparoscopic procedures to the pelvic nerves became available, Pr. Possover began identifying cases where endometriotic lesions were affecting the sciatic nerve. This led him to a deeper understanding of the disease's capacity to extend beyond the pelvic organs, affecting nerve structures and causing symptoms that can mimic other neuropathic conditions.

More than 20 years ago, Professor Possover was one of the first gynecologists to take an interest in a very unique form of endometriosis affecting pelvic nerves. From the beginning, he observed that sciatic nerve endometriosis seems to develop always in the same location around or within the intrapelvic portion of the sciatic nerve, just before the nerve exits the pelvic cavity to enter the buttock. In parallel, he noted that endometriosis of the sacral plexus appears to be a lateral extension of endometriosis on the uterine ligaments (Possover M (2007) Laparoscopic neurolysis of the sacral plexus and the sciatic nerve for extensive endometriosis of the pelvic wall. Minim Invasive Neurosurg 50: 33-36. - Possover M, Chiantera V (2007). Isolated infiltrative endometriosis of the sciatic nerve: about three cases. Fertil Steril 87: 417-9.   -   Link: https://pubmed.ncbi.nlm.nih.gov/?term=possover)

Possover thus proposed the hypothesis that sciatic nerve endometriosis might represent a distinct neurological manifestation, independent of the more common endometriosis of reproductive organs (Possover M, Kerstin Rhiem, Vito Chiantera. (2005) The “neurologic hypothesis: a new concept in the pathogenesis of the endometriosis? Gynecolog Surge 2 (2): 107-111). He also recognized that patients with this unusual type of endometriosis typically seek help from orthopedic surgeons, neurologists, or neurosurgeons, rather than gynecologists.

For nearly a decade, he worked to raise awareness about this condition at medical conferences, during a time when sciatic nerve endometriosis was considered extremely rare in gynecology—or even nonexistent.

Today, Prof. Possover has by far the largest series of sciatic nerve endometriosis cases in the world, having performed over 500 surgeries in the past 20 years (Possover M. Five-Year Follow-Up After Laparoscopic Large Nerve Resection for Deep Infiltrating Sciatic Nerve Endometriosis. J Minim Invasive Gynecol. 2017 Jul - Aug;24(5):822-826). However, this condition remains fortunately rare. Its rarity makes it particularly challenging for an endometriosis surgeon to gain enough experience in operating on this disease, which falls within both the fields of neurosurgery and pelvic vascular surgery. In fact, the major risk in this surgery - aside from the risk of an incomplete procedure and the potential for recurrence - is the risk of vascular hemorrhage, which can be life-threatening if the surgeon does not have a strong mastery of vascular surgery principles.

For his work on this disease over the last 20 years, Prof. Possover was recognized in 2022 by the European Society for Gynecologic Endoscopy, which awarded him the prize for the best scientific work of the year - Ivo Brosens Award – Prize for the Best Scientific Journal Article – ESGE 31st Annual Congress – Lisbon- Portug

• Sacral Plexus Endometriosis:Endometriosis involving the sacral plexus is also uncommon. Specific prevalence or incidence rates are not well-documented, but it is considered a rare occurrence. 

In summary, endometriosis affecting the sciatic nerve or sacral plexus is rare, with limited cases reported in medical literature. The exact prevalence and incidence rates are not well-established, highlighting the need for increased awareness and research into these uncommon presentations.

3. Challenges in Diagnosis

Due to their rarity and the similarity of symptoms to more common conditions like lumbar disc herniation, these forms of endometriosis are often misdiagnosed, leading to delays in appropriate treatment. 

Deep infiltrating endometriosis is usually associated with a multitude of symptoms and constitutes a complex challenge to treatment. Awareness that endometriosis of the pelvic somatic nerves exists has increased over the last few years but is still too little known in medical community.

Endometriosis of the sacral plexus and of the sciatic nerve are two different entities with different clinical aspects:

• Sacral Plexus Endometriosis which results from an infiltration of the SNR at the dorsal compartment of the pelvic cavity by extension of a genital endometriosis (parametrial endometriosis), resulting in cyclical sciatic/low back pain with genitoanal/pudendal pain and hypersensitivity of the bladder, urgency, nocturia or pseudo-IUT - https://www.youtube.com/watch?v=NUq5pfG6h_c (Possover M. Laparoscopic neurolysis of the sacral plexus and the sciatic nerve for extensive endometriosis of the pelvic wall. Minim Invasive Neurosurg 2007;50:33-6. - Chiantera V, Petrillo M, Abesadze E et al. Laparoscopic neuronavigation for deep lateral pelvic endometriosis: clinical and surgical implications. Minim Invasive Gynecol 2018;25(7):1217-23). Where neuronal lesions of the sacral nerves root are present, patients present difficulties in flexion of the toes and difficulties in bladder voiding (incomplete emptying) and chronic constipation.

• Endometriosis of the Sciatic Nerve - https://www.youtube.com/watch?v=T6HnkANC4t4: This very particular form of the disease develops primarily at the intrapelvic portion of SN and not by extension of a genital endometriosis, with potential involvement of the obturator and pudendal nerves, and by further retroperitoneal extension the homolateral ureter (Possover M, Chiantera V. Isolated infiltrative endometriosis of the sciatic nerve: about three cases. Fertil Steril 2007;87:417-9. – Possover M. Laparoscopic therapy for endometriosis and vascular entrapment of sacral plexus. Fertil Steril 2011;95(2):756-8). Contrary to classical genital deep infiltrating endometriosis that progresses slowly, endometriosis of the SN is a rapidly progressing and aggressive disease, with the onset of neurological disorders by nerve destruction already apparent after 2 years. 

Source: Possover M. Laparoscopic morphological aspects and tentative of explanation the etiopathogenesis of isolated endometriosis oft he sciatic nerve: a review based on 267 patients. Facts Views Vis Obgyn, 2021;13(4): 331-337

Left: small ESN <2mm in diameter – Right: urge endometrioma within the sciatic nerve (>30% of the nerve)

Endometriosis of SN must be considered in the differential diagnosis in all young patients suffering from cyclical sciatica with no identifiable spinal or musculoskeletal etiology. The cyclical nature of the pain is pathognomonic of the disease but only at the beginning of its evolution. The appearance of neurologic disorders of the lower limb, in particular difficulties in climbing stairs (foot drop), walking disturbances and disturbances of the flexion of the ankle (loss of Achilles reflex), are the main clinical signs. Transvaginal examination of the sacral plexus reproduces a massive trigger sciatic pain. The disease can be visualized with MRI (but not always - depending on the size of the disease and depending on the experience of the radiologist with ESN).

4. When to see a doctor

Patients suffering from ESN or ESP should consider seeing a doctor when they experience the following clinical signs and symptoms, especially if these symptoms are persistent, worsening, or impacting their quality of life.

Clinical Signs and Symptoms Indicating the Need for Medical Evaluation

• If you feel the need to urinate more than eight times in a 24-hour period, including waking up multiple times at night (nocturia).
• If you experience difficulty emptying your bladder.
• If you have symptoms of sciatic pain, including:

• Sharp or shooting pain radiating from the lower back to the leg.
• Tingling or "pins and needles" sensation in the leg or foot.
• Weakness or numbness in the leg or foot, with difficulty walking or moving your ankle or toes.
• Pain that worsens during menstrual bleeding.

• If you have abnormal sensation or numbness in the lower back, buttock, or back of the leg.
• If you develop burning pain in the genital or anal areas (“pudendal pain”)

When to See a doctor

1. If these symptoms are persistent, lasting for several weeks or longer, it’s important to seek medical advice.
2. If the symptoms are affecting your ability to perform daily activities, interfering with sleep, or causing emotional distress, a doctor’s evaluation is necessary.
3. If you are unsure whether your symptoms are due to endometriosis or another condition (e.g., vascular entrapment, tumor of the pelvic nerves, surgical injuries…), a certified ISON Level 3 can help differentiate the cause.

Early diagnosis and treatment of endometriosis of the pelvic nerves can prevent the condition from worsening, irreversible neurological disorders and help improve quality of life. Additionally, seeing a neuropelveologist certified ISON level 3 can help rule out other potential causes of pain symptoms, ensuring that you receive the appropriate care.

5. How to do the diagnosis

The diagnosis of endometriosis of the sciatic nerve or of the sacral plexus involves a comprehensive Neuropelveological assessment (it’s not Gynecology!!!) that includes a detailed patient history, Neuropelveological physical examination, and various tests to rule out other conditions with similar symptoms. Here's an outline of the diagnostic process for ESN and ESP:

• Patient’s history: This helps to determine whether endometriosis has already affected or even infiltrated the nerves. The treatment of the disease depends primarily on this information to identify which nerves and at what level in the pelvis are involved. This allows us to determine whether it will suffice to excise the disease from the nerves or if the disease has already infiltrated and partially damaged the nerves. In such cases, the disease must be removed from the nerve along with the affected section of the nerve tissue, all without causing a complete transection of the nerve, which would be catastrophic for the patient and would result in permanent walking difficulties for the rest of her life."

In Prof. Possover's Center, a neuropelveology consultation typically lasts around 2 hours, with more than half of this time dedicated to the patient’s medical history—an essential step for an accurate neuropelveological diagnosis, which directly affects the quality and outcomes of the treatment.

• Neuropelveological Examination: The neuropelveologist may check for any gynecologic conditions but may extend the examination to the pelvic nerves locking for any neurological disorder of the sacral plexus or sciatic nerve.
• Vaginal Sonography with doppler flow for evaluation the blood vessels at the pelvic side wall and around the disease – for a better planning of the procedure.
• Post-Void Residual (PVR) Measurement: After the patient urinates, the amount of urine left in the bladder (post-void residual) is measured with Ultrasound. This test can help determine if the bladder is emptying completely or if there is urinary retention, which may indicate some damages to the pelvic nerves.
• Imaging Studies (CT-scan - MRI): Imaging may be used to visualize the pelvic nerves but also the kidneys, bladder, and other pelvic organs to exclude structural abnormalities or masses that could also be causing the symptoms.

The diagnosis of endometriosis of the pelvic nerves is typically made after a careful evaluation of symptoms, exclusion of other conditions. It’s important to approach the diagnosis systematically to ensure that the correct condition is identified and treated appropriately, but also to avoid unnecessary surgery to the pelvic nerves!!!

5. Complications of endometriosis of the sciatic nerve or the sacral plexus

When endometriosis infiltrates and damages the sciatic nerve or the sacral plexus, it can lead to significant and potentially permanent consequences. The sciatic nerve is the largest nerve in the body, responsible for motor and sensory function in the lower limb. Damage to it can result in:

1. Severe Pain: Patients often experience intense, chronic pain in the lower back, buttock, and along the leg, which can worsen with movement and may be unrelieved by typical pain medications.
2. Muscle Weakness or Paralysis: As the sciatic nerve controls major muscles of the leg, damage can cause muscle weakness, impacting the ability to walk, stand, or bear weight. Severe damage may lead to paralysis of certain leg muscles, resulting in a “foot drop” (difficulty lifting the front part of the foot) and unsteady gait.
3. Numbness and Sensory Loss: Damage can lead to numbness or altered sensations, like tingling or “pins and needles” in the lower leg and foot, often affecting balance and mobility.
4. Loss of Reflexes: The loss of tendon reflexes, such as the ankle-jerk reflex, may occur, leading to further instability and difficulty with movement.
5. Permanent Mobility Impairment: Severe or untreated damage can result in lifelong mobility issues, requiring mobility aids to restore some function.
6. Bladder and Bowel Dysfunction: In ESP, damage may extend to nerves affecting bladder and bowel function, leading to incontinence or difficulty with bowel movements.

Preventing complete sciatic nerve destruction by timely diagnosis and specialized treatment is crucial.

6. Treatment

In the early days of treating sciatic endometriosis, the focus was largely on managing pain through hormonal therapies aimed at reducing estrogen levels, which can drive the growth of endometriotic tissue. Because of failure of medical treatments with irreversible neurologic damages in these patients, laparoscopic intervention became a key treatment strategy, especially as imaging techniques like MRI improved, allowing for better localization of endometriotic lesions on or around the sciatic nerve. However, surgery in this area is highly complex and extremely dangerous due to the intricate anatomy, major vessels and the risk of nerve damage. Early surgical techniques focused on removing visible endometriotic lesions but often did not fully address the nerve involvement, leading to variable outcomes for the patients.

Hormonal treatments have no place in the treatment of endometriosis of the pelvic nerves! Treatment may involve laparoscopic surgical excision of the endometriosis eventually with partial resection of the nerve while preserving as much nerve function as possible, as well as targeted rehabilitation to mitigate the effects on mobility and sensation.

Sciatic endometriosis may be treated the same way as deep infiltrating endometriosis of the pelvic organs by laparoscopic resection including nerve decompression and partial nerve resection. Such interventions are probably the most challenging surgery in the pelvis and may be reserved only for surgeons experienced in laparoscopic retroperitoneal surgery, multiple pelvic organs surgery and Neuropelveological procedures. Laparoscopic treatment of pelvic nerve endometriosis can be done with great results in terms of pain improvement and low risk of recurrence, and functional outcome is good as long as part of the nerve is preserved, and patients are properly supported by intensive physiotherapy⁸.

Sciatic nerve endometriosis surgery is a very challenging laparoscopic procedure that has only the name of endometriosis. In fact, it is radical surgery, much like in cancer treatment, because leaving any part of the disease behind does not result in recurrence but in persistence and progression of the disease. Each additional surgery on the sciatic nerve area becomes progressively more difficult, with an increasing risk of vascular injury. Due to the fibrosis from previous interventions, it becomes increasingly difficult to distinguish scar tissue from the endometriosis itself. Likewise, identifying and exposing the nerve within the scar tissue becomes progressively harder. Therefore, in sciatic nerve endometriosis surgery, there is no room for ‘good enough.’ Either the surgeon has experience in this field, or they do not. Experience in gynecologic cancer surgery or severe endometriosis surgery alone is not sufficient for this very specialized procedure. Sciatic nerve endometriosis surgery is among the most difficult surgeries in the pelvis and is a ‘one-shot surgery’ with no room for error. Very few surgeons, even among ISON Level 3 certified neuropelveologist, have experience in this surgery, which remains rare due to the low prevalence of the disease. This highly specialized surgery must be performed in a few select centers by a neuropelveologist experienced in nerve surgery, with essential expertise in managing pelvic vessels.

Neurosurgeons are specialists in nerve surgery. However, they are not trained in laparoscopic surgery of the pelvic nerves. The neurosurgical approach to the sciatic nerve, accessed through the buttock, does not allow treatment of the intrapelvic portion of the nerve, where the disease develops. Thus, a dorsal approach through the buttock is almost always incomplete, ensuring the persistence of the disease.

Extensive experience in advanced endometriosis surgery of the pelvic organs is insufficient for the surgery of endometriosis or any other pathology (such as schwannoma, surgical injuries...) affecting the sciatic nerve.

Tips for a good doctor’s visit and questions to ask

To make the most out of a doctor's visit when you're suffering from cyclical sciatic pain and suspicion of endometriosis of the sciatic nerve it’s important to prepare in advance and actively participate in the consultation. Here are some tips to ensure a productive and helpful visit:

1. Prepare a Symptom History: Note the onset of the symptoms, the evolution of the symptoms, the onset of neurological disorders. This information will help your doctor understand the severity of your condition and identify potential patterns or triggers.
2. List Your Medications
3. Prepare Questions and Concerns

• Make a List: Write down any questions or concerns you have about your symptoms, treatment options, side effects, or lifestyle changes. This ensures you don’t forget anything important during the visit.
• Ask About Diagnosis and Tests: If you’re uncertain about your diagnosis, ask your doctor how they reached it, and if any further tests are needed.

4. Be Honest About your Symptoms

• Full Disclosure: Be open about your symptoms, even if you feel embarrassed. Doctors are trained professionals, and full disclosure is essential for accurate diagnosis and treatment.
• Quality of Life Impact: Explain how you pain, or functional disorders are affecting your daily life, including work, sleep, and social activities. This can help your doctor understand the urgency of finding an effective treatment.

5. Understand Treatment Options

• Ask About All Options: Inquire about all possible treatments, including lifestyle changes, medications, physical therapy, and surgical options.
• Side Effects and Benefits: Discuss the potential benefits and side effects of any proposed treatment to make an informed decision.
• Long-Term Management: Ask about what you can do to manage your symptoms in the long term, including follow-up visits and ongoing care.

6. Plan Follow-Up Care

• Schedule a Follow-Up: Make sure to schedule a follow-up visit to assess the effectiveness of the treatment and make any necessary adjustments.
• Know When to Call: Ask your doctor when you should return for a visit or contact them if symptoms change or worsen.

8. Bring a trusted friend or family member to the appointment. They can help you remember details or ask questions you might forget.
9. Be Open to Recommendations: Be willing to try the treatment plan your doctor recommends and give it time to work before making judgments. Be also open to making lifestyle changes as advised by your doctor, as they can significantly impact your symptoms.
10. Follow-Up on Test Results: If any tests are ordered, ask when and how you will receive the results. Follow up if you don’t hear back in the expected timeframe.

Try to found out if your physician is trained in neuropelveology, and certified from the ISON and have already publish on this pathology /see: https://pubmed.ncbi.nlm.nih.gov/ and enter the name of your doctor to see his publications on this issue.