What is spinal neuroma and methods of its treatment

The current approach to the treatment of neurogenic tumors varies depending on the location of the tumor, its size and the potential risks of the chosen method. Treatment of tumors of the sacral region is a complex surgical task due to the fact that in most cases combined anteroposterior approaches are required. With this approach, there is a high risk of damage to blood vessels, nerve structures or the wall of the rectum, which are always intimately adjacent to the tumor capsule.

Neurogenic tumors are extremely rarely localized in the pelvic area. Thus, T. Rasmussen et al. [1] found only 35 (7%) cases of neurogenic sacral tumor among 557 patients with spinal tumors. Database analysis confirms that for every 40,000 patients with spinal tumors, there is only one with a neurogenic sacral tumor. Most patients with neurogenic tumors of the sacral location have neurofibromatosis [2].

As a rule, the manifestation of the disease occurs in the case of progression of the tumor process. This may be accompanied only by local or radicular pain, less often by dysfunction of the pelvic organs. The appearance of symptoms always indicates the beginning of progressive tumor growth, and in cases where a large tumor is detected, its malignancy should be suspected [3-5]. Neurogenic tumors rarely infiltrate bone tissue. Even in the case of malignant transformation, local growth is often expansive, however, this often leads to the destruction of bone tissue. Considering the possibility of malignant transformation of a neurogenic tumor, even small tumors of a neurogenic nature should be radically removed [6].

One of the treatment options for a neurogenic tumor of the sacrum, in the absence of significant symptoms, is stereotactic radiation therapy [7–10].

The approach to a neurogenic tumor of the sacrum is selected depending on the location of the tumor, its size and adjacent structures.

Thus, according to the findings of P. Klimo et al. [11], all neurogenic tumors of the sacrum can be divided into three types (Fig. 1).

Rice. 1. Classification of neurogenic tumors of the sacrum by type of growth. Type I - intracanal tumor growth; Type II - anteroposterior type of growth with expansion into the pelvic area and growth of the sacral tire; Type III - anterior type of growth, mainly towards the pelvis.

The authors suggest a specific approach for each type of tumor growth: for type I tumors, in their opinion, a posterior approach can be used; for type II tumors - a combined anteroposterior approach or only a posterior approach; for type III tumors, it is advisable to use a combined posteroanterior approach, which involves isolating the source of tumor growth - the nerve root of the sacral localization and intersection in the area of ​​its healthy part, followed by foraminal dissection of its cuff to facilitate isolation tumors via anterior approach. Then the tumor is removed using an anterior retro- or transperitoneal approach.

Our article presents a case of removal of a type II tumor. Radical resection was achieved by amputation of the sacrum below the S1 body only from the posterior approach.

Clinical case

Patient P

., 23 years old, applied to the Neurosurgery Center named after. N.N. Burdenko in 2015 with complaints of severe local pain in the sacral region, in the perineum and impaired sensitivity in the anogenital zone. MRI/MSCT (spiral computed tomography) revealed a sacral tumor with a cystic component and bone destruction at the S1-S5 level (Fig. 2).

Rice.
2. MRI of the sacrum, T1-weighted image in the sagittal projection (arrow marks the tumor). Given the complex configuration of the tumor and destruction of bone tissue, the diagnosis was questioned. Therefore, the first stage was a diagnostic puncture CT biopsy of the tumor under the control of a navigation system. During pathomorphological examination of the biopsy specimen, a diagnosis was made: neuroma.

Considering the dynamic MRI data of the sacral region - an increase in tumor size, as well as the absence of gross neurological symptoms, in order to preserve the function of the pelvic organs, it was decided to perform radiation therapy instead of radical resection. Stereotactic hypofractionated radiation therapy was performed using the Cyber-Knife device (bremsstrahlung photon radiation from electrons 6 MeV). The tumor volume is 90 cm3. The average single focal dose is 5.2 Gy, the average focal dose is 26 Gy.

The observation period was 24 months. During this time, there were no significant changes in the neurological status; on the contrary, 3 months after radiation therapy, the pain syndrome regressed. However, in 2017, the patient again noted the appearance of local pain. The appearance of rectal bleeding, which was not associated with hemorrhoidal lesions of the veins, was also alarming. Sigmoidoscopy revealed no erosions, cracks, ulcerations or tumor penetration of the intestinal wall. At the same time, given the amount of non-steroidal anti-inflammatory drugs used, this bleeding could be an expected complication. According to control MRI/SCT studies of the lumbosacral region with contrast enhancement, continued tumor growth was determined at the S1-S5 level (Fig. 3).

Rice. 3. Continued growth of the sacral tumor after stereotactic radiation therapy. a — SCT of the lumbosacral region in the sagittal projection; b — 3D image constructed from computed tomography, median section in sagittal projection; c — SCT of the sacrum in the axial projection.

The patient was offered surgical treatment. Taking into account previous radiation therapy and the nature of tumor growth, radical tumor removal with simultaneous lumbopelvic trans-S2 stabilization and pelvic floor plastic surgery was planned. Stabilization was considered due to the possibility of postoperative stress fracture of the remnant sacrum and instability.

Operation stages

Position the patient on her stomach. The incision is linear, along the spinous processes and slightly lateral to the intergluteal fold (Fig. 4).

Rice. 4. Position of the patient on the operating table and marking of the future incision. a - schematic representation of the patient’s position on the table, the position changes before stabilization. The frame is lowered to create maximum lordosis; b - schematic representation of the projection of a linear section. The dotted line marks the area of ​​skeletonization of the pelvic bones; c — intraoperative photo: a marker shows the dotted line of the incision.

The sacrum is skeletonized, it is noted that the sacral covering is destroyed in the S2-S3 zone (Fig. 5).

Rice. 5. Intraoperative photo. Skeletonized sacrum. A reference frame was installed on the spinous process before the laminectomy stage.

A laminectomy of S1 was performed, the roots below S2, which were part of the tumor parenchyma, were ligated, a cut was made to the healthy bone of the sacrum below the S1 vertebra, the sacrotuberous and coccygeal-tuberous ligaments, piriformis were crossed, then the presacral fascia was disconnected from the rectal wall, the nerves of the sacral plexus were crossed at peripheral segment (Fig. 6).

Rice. 6. Intraoperative photo. a — laminectomy was performed (arrow indicates tumor tissue); b — the sacral ligaments are crossed, the sacrum is elevated to disconnect the rectal wall from the presacral fascia.

The tumor along with the sacrum was removed en bloc. Transpedicular stabilization of L5—S1 and lumbopelvic stabilization through the lateral masses of the sacrum at the S2 level were performed (Fig. 7).

Rice. 7. Intraoperative photos. a — bed of the removed tumor, free S2 roots are visible (shown by white arrows); b — type of installed lumbopelvic stabilizing system; c — pelvic floor plastic surgery was performed with polypropylene material, the area of ​​the ligated roots was additionally covered with plastic material; d — block of the tumor removed from the sacrum in the anteroposterior and lateral projections; d — intraoperative 3D reconstruction of radiographs. Type of stabilizing structure.

The last stage was soft tissue plastic surgery by suturing free muscle flaps of the gluteal muscles, the skin was sutured with an intradermal suture (Fig. 8).

Rice. 8. Schematic representation of the selection of free flaps of the gluteus maximus muscles (a, b) and the appearance of the wound after healing (c).

In the postoperative period, the patient was activated on the 1st day after surgery. The wound discharge was drained for 5 days.

On the control MRI there are no signs of a tumor, signs of a serous cavity, perineal hernia or other complications (Fig. 9).

Rice. 9. MRI of the lumbosacral spine in 3 projections 2 months after surgery. a — sagittal projection; b - frontal projection; c — axial projection.

Urological rehabilitation was carried out for 3 months after the operation: electrical stimulation of the bladder, periodic catheterization, physical therapy, and taking cholinomimetics. After 3 months, there was a decrease in the amount of residual urine to 20-50 ml, no episodes of urinary retention or incontinence, and normal bowel movements. The only manifestation of discomfort was a violation of sensitivity in the anal area in the form of superficial hypoesthesia.

Causes of malignant neuroma

The exact causes of the disease have not yet been clarified. It is believed that the appearance of malignant neuroma is promoted by:

• burdened heredity;
• ionizing radiation (the latent period after exposure to this factor can last up to 15 years);
• contact with asbestos or wood preservatives;
• immunodeficiency;
• benign neuroma (but malignancy is rare);
• ganglioneuroma (but degeneration is rare);
• neurofibromatosis (but malignancy is rare).

Description of the disease

Neuroma is a benign pathological formation that develops from the myelin tissue of the nerve canal. The consequences of the growth of abnormal fibers are systematic irritation of the nerve, loss of its functionality, and compression of adjacent areas. The disease is well studied, the description and term were introduced in the first decade of the 20th century. The neoplasm can occur in any of the areas of the nervous system: cerebral, spinal, peripheral. Female representatives are more susceptible to this anomaly. The most common area for neuroma to develop is in the peripheral areas, especially the auditory nerve and spinal roots. The next most common are:

• cranial neural channels;
• nerve pathways located in the limbs;
• pharynx;
• Gastrointestinal tract.

Symptoms of malignant neuroma

The clinical picture of malignant neuroma is characterized by certain features. The tumor has the following pathognomonic characteristics:

• localized on the limbs;
• may sometimes appear on the neck and head;
• located along the nerves;
• single or multiple large-tuberous nodes;
• may occur in the form of a spindle-shaped thickening (with damage to nerve trunks);
• dense consistency;
• clear boundaries;
• the value does not exceed 12 – 15 cm;
• no pain on palpation;
• no change in the skin over the tumor (sometimes mild erythema is visualized);
• pain (50%);
• neurological disorders in the form of paresthesia (rare).

Most often, malignant neuroma develops in deep tissues. With a rarer superficial location, it can grow into the skin with the formation of ulcers. In addition, the tumor can invade the bones, causing their destruction.

Metastasis occurs through hematogenous (to the lungs) and lymphogenous (to lymph nodes) routes. Recurrence of malignant neuroma is also possible.

Discussion and conclusions

Various tumors occur in the sacral area, most often primary bone tumors: chordoma, giant cell tumor. Neurogenic tumors make up only a small proportion of neoplasms found in the sacral region. Moreover, the behavior of these tumors, as a rule, is characterized by an aggressive growth pattern and frequent malignant transformation of tumor tissue [12–14]. Malignancy more often occurs in cases of prolonged growth of xanthomatous neurofibroma. A tumor biopsy sometimes provides little information, since during puncture the surgeon aims at the most massive part of the tumor, and the material taken does not always contain the degenerated part.

In the described case, the choice of the type of resection was dictated by the fact that the tumor completely destroyed the sacrum in the S2-S5 zone, in addition, the risk of malignancy was especially significant after radiation preceding the continued growth of the tumor.

Literature data [9, 10] provide cases of the formation of secondary tumors or malignancy of benign tumors after conventional radiation therapy. Therefore, most authors consider radiation therapy to be a risky treatment.

However, current practice shows that radiosurgery or hypofractionated high-dose radiation therapy is an alternative to surgical methods for treating patients with neurogenic tumors in the spine [7, 8]. However, most publications present single observations or analysis of treatment in small series of patients. Therefore, it is extremely difficult to predict the outcome of treatment. In our observation, according to MRI data, after irradiation there was an increase in tumor volume, with pain, as well as a risk of tumor malignancy. All this became the basis for the decision to undergo surgical treatment.

Various aspects of surgical treatment are quite well described in the literature. J. Feldenzer et al. [15] operated on 9 patients. Two of them underwent combined tumor removal from an anteroposterior approach, the rest were operated on only from a posterior approach. At the same time, 2 patients from the posterior approach group had malignant tumors of the peripheral nerves and died during 3 years of observation; the rest had no signs of tumor recurrence. J. Domínguez et al. [16] describe in their publication 6 patients with giant sacral schwannomas. Two underwent an anteroposterior approach to remove the tumor; the rest underwent a posterior approach. Tumor recurrence was observed in 3 patients with an intradural component of the tumor, and in 1 patient the recurrence occurred 17 years after surgery. In a series of observations by C. Abernathey et al. [17] 10 patients were operated on only from the posterior approach, 3 patients - from the anterior approach. In 4 patients, removal of the intrathecal component of the tumor was required. Total removal was noted by the authors in 4 cases. Nine patients who underwent partial tumor resection were asymptomatic during the entire follow-up period, but 4 (44%) patients required reoperation. All of these 4 patients had no signs of continued tumor growth or malignancy during 7–84 months of follow-up. During their treatment, an additional anterior approach was used to remove the tumor in 3 cases, and a combined anteroposterior approach was used in 1 case. One patient required additional pelvic stabilization, but the authors did not indicate the reasons for this. Complications included dysfunction of the pelvic organs in 1 patient, sensory disturbances in the anogenital area in 4 patients, motor disorders and problems with movement in 1 patient. Wound complications were described in 3 patients.

In modern specialized literature, there are no examples of sacral amputation or total sacrectomy in the treatment of patients with potentially benign or potentially malignant sacral tumors, since sacrectomy is considered the method of choice for the treatment of patients with locally aggressive or completely malignant, mainly bone, sacral tumors.

In the case we described, partial resection of the tumor did not make sense and would have led to tumor recurrence. In addition, the S3-S5 roots passed through the tumor parenchyma, so the decision to en bloc resection of the sacral tumor was justified.

An interesting fact is that in the postoperative period the patient experienced only transient dysfunction of the pelvic organs. This was due to the preservation of the anatomical integrity of the S2 roots on both sides. According to the literature, the preservation of the S2 roots is the key to preserving the function of the bladder sphincter, while the preservation of the normal act of defecation depends on many factors, in particular on the preservation of normal pelvic floor function and the preservation of the sensitivity of filling and emptying of the rectal ampulla.

J. Wilfrid [18] uses data from O. Foerster et al., who described back in 1927 the multiplicity of options for the innervation of the pelvic organs, which makes possible the reinnervation of the pelvic organs and determines positive dynamics as a result of rehabilitation (see table).

Variants of innervation of the pelvic organs according to O. Foerster et al. (1927)

Another important problem that often complicates the postoperative course in the area of ​​sacral resection is instability in the sacroiliac joint. Typically, instability develops as a result of resection of more than 50% of the sacroiliac joint or due to osteoporosis or prolonged excessive load and requires additional stabilization and restoration of continuity of the pelvic ring [19].

Following all precautions and taking into account world experience, we completed the operation with lumbopelvic stabilization.

Diagnosis of malignant neuroma

If the doctor has suspicions after a physical examination of the patient to exclude malignant neuroma, he will refer the patient for the following examinations:

• fluoroscopy, CT/MRI of the affected area (the formation is visualized, its growth into the bone can be determined);
• cytological examination of a tissue sample (biopsy);
• morphological analysis of biopsy samples (microscopically, multidirectional bundles of atypical elongated cells with hyperchromatic nuclei and mitoses are detected).

Possible consequences of surgery

Unfortunately, the percentage of negative consequences after performing operations is large, and all of them are complex in nature. Eliminating negative feelings in the future is very difficult, and in many cases impossible. Due to mechanical damage to the nerve roots, paralysis or paresis may occur. With paralysis, the patient completely loses the ability to move; with paresis, movements are severely limited. The most minor negative consequences are muscle weakness with further trophic changes. The changes are irreversible; special medical measures and exercise therapy can only slightly slow down the development of the pathology.

About the consequences of pathology

Treatment of malignant neuroma

After verifying the diagnosis, doctors try to determine the most appropriate tactics for further action for a particular patient. Combination treatment is more often used. It includes:

• traditional surgical intervention (wide excision of the tumor involving intact tissue or amputation of the affected limb);
• methods of stereotactic radiosurgery (a gamma knife with high-dose radio exposure is used);
• radiation therapy (as an addition to the surgical method, if only subtotal resection of the neuroma can be performed);
• chemotherapy (cytostatics).

conclusions

Radical resection of giant neurogenic tumors of the sacral region may possibly reduce the potential for local tumor recurrence and thereby prevent local malignancy and improve patient survival. Despite the high risk of neurological, wound, intraoperative complications, as well as possible lumbopelvic destabilization, en bloc tumor resection remains a justified treatment method. Restoring the lost quality of life as a result of surgical trauma is one of the most important tasks of future research to find opportunities for rehabilitation of pelvic functions in patients who have undergone various types of sacrectomy.

The authors declare no conflict of interest.

*e-mail: [email protected]

Rehabilitation period

The rehabilitation period can last up to four months. Its duration depends on many factors: for example, how severe the patient’s condition was after the operation and before it, what the neuralgic symptoms are, whether positive dynamics are observed after the treatment. More often, the following procedures are prescribed for faster rehabilitation:

• physiotherapy;
• massotherapy;
• exercises.

During the rehabilitation period, it is important to pay attention to exercises and therapeutic massage.

A well-performed operation to remove a tumor and a correct recovery course after it guarantee a fairly good prognosis, full restoration of performance and an improved quality of life. The exception is the case when the neuroma was malignant.

In cases where compression of the spinal cord was not caused by a tumor, impairment of the motor system may persist for a long time.

Symptoms of pathology

Depending on the location of the tumor object, specific symptoms of damage to a particular nerve appear. The development of education occurs at a slow pace, symptoms may not appear for a long period of time. The main criteria for suspecting this type of disease are a disorder of nervous functionality in one area of ​​the body and changes that occur when the tumor presses on neighboring areas.

Obvious signs of schwannoma in the following parts of the nervous system:

• Auditory nerve. Gradual decrease in sound perception on the affected side. Since the functionality of only one ear changes, the patient may not immediately notice the development of deafness.
• Vestibular apparatus. Partial loss of coordination, dizziness, attacks of nausea and vomiting not associated with meals.
• Trigeminal nerve. Loss of sensitivity of the skin on one side of the face, changes in taste perception, weakening of facial muscles.
• Spinal root. Soreness, numbness in the affected area, atrophy of the back muscles, weakness in the arms and legs.
• Nerves of the pharynx. Discomfort, sensation of a foreign object in the throat, difficulty breathing through the nose.

With prolonged tumor growth, complications can develop such as complete hearing loss, degeneration of the facial muscles, increased intracranial pressure, impaired swallowing, difficulties in speech reproduction, impaired visual function, uncontrolled sweeping movements, loss of coordination, unsteadiness during movements, loss of sensation in the lower back and legs, incontinence.

Clinical picture

As mentioned earlier, neuroma is most often diagnosed in the neck, then neuroma in the thoracic region and in third place - the lumbosacral region. Such tumors are located exclusively around the spinal cord, and not outside it. Severe compression, pain and other indicative syndromes appear.

So, what should you pay attention to initially? Firstly, this is radicular pain syndrome. Symptoms directly depend on which root is damaged. When a tumor forms on the anterior roots, it can lead to paralysis. When the dorsal roots are affected, sensitivity in the limbs is lost and discomfort appears in the back. Weakness in the lower extremities, numbness, tingling, and stiffness when walking also often occur.