Efficacy of Posterior Tibial Nerve Electrical Stimulation on Chronic Pelvic Pain Syndrome

Efficacy of Posterior Tibial Nerve Electrical Stimulation on Chronic Pelvic Pain Syndrome

Marwa M.Eid,

Department of Physical Therapy for Surgery, Faculty of Physical Therapy, Cairo University, Giza, Egypt.

Abstract

Objectives: This study was conducted to investigate the efficacy of posterior tibial nerve electrical stimulation on chronic pelvic pain syndrome Subjects and Methods: Fifty patients who were suffering from chronic pelvic pain participated in the present study. They were selected randomly from" the national institute of urology and nephrology". Their ages ranged from 40 to 65 years old ,Patients were classified randomly into two equal groups. Group I: consisted of twenty five patients who were treated by electrical stimulation of the posterior tibial nerve stimulation (PTNS) 10 MA, 1-10 Hz frequency and a fixed pulse duration 200 microsecond with 15-minute sessions given 3 times per week for 10-12 weeks)in addition to traditional medical care. Group II: consisted of twenty five patients who received placebo electrical stimulation in addition to traditional medical care. Measurement tools :VAS &McGill pain questionnaires used for pain assessment pre and post treatment. Results There was no significant difference between both groups (control and study) in the mean values of VAS pre-treatment & highly significant decrease after 12 weeks of application of electrical stimulation in the study group compared with control group .There was no significant difference between both groups in mean values of McGill Pain Questionnaire score pre-treatment & significant decrease after 12 weeks of application of electrical stimulation in the study group when compared with the control group .Conclusion Posterior tibial nerve electrical stimulation is effective in treating chronic pelvic pain as manifested by decreased Visual analogue scale and McGill Pain Questionnaire scores.

Key Words :Posterior Tibial Nerve, Electrical Stimulation, Chronic Pelvic Pain Syndrome.

Introduction

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is characterized by pain can range from mild discomfort to debilitating. Pain may radiate to back and rectum, making sitting difficult. Dysuria, arthralgia, amyalgia, unexplained fatigue, abdominal pain, constant burning pain in the penis, and frequency may all be present. Chronic pelvic pain is a common problem with a high impact on patients’ quality of life (1).The syndrome is characterized by chronic pain of the perineum, lower back, inguinal, scrotal and suprapubic region without findings of infection (2,3,4).Pelvic pain is a symptom that can affect both women and men. The pelvic pain that persists for a period of 3 months or more to be considered chronic while less than this duration is considered acute. The pain may indicate the existence of poorly-understood conditions that likely represent abnormal psycho neuromuscular function (5).The basic cause of chronic pelvic pain is difficult to locate. But once the cause has been identified, the treatment focuses on resolving that cause, and if the cause is un-identified, the treatment focuses on techniques which can be helpful in managing the ache (6).

Posterior tibial nerve stimulation (PTNS) is a form of neuromodulation used to treat chronic pelvic pain in chronic prostatitis (CPPS). It can also be used to treat urinary incontinence. Sometimes this is called "Percutaneous Tibial Nerve Stimulation". PTNS is an in-office procedure that uses a stimulator, which generates an electrical impulse that is delivered to the patient through a lead set. Using a needle electrode placed near the ankle as an entry point, the stimulator’s impulses alter the activity of the bladder by traveling along the tibial nerve to the nerves in the spine that control pelvic floor function (7). The mechanism of action of neuromodulation is still unknown, although many theories exist. In lower urinary tract dysfunction neuromodulation most probably causes rebalancing of inhibitory and excitatory impulses that govern bladder function in the central nervous system (8).For pain it can be suggested that, according to the gate control theory, stimulation of large somatic fibers could modulate/inhibit the thinner afferent A-delta or C fibers, thus decreasing pain perception (9).

Materials and Methods

Subjects: Fifty volunteer male patients who were complaining from chronic pelvic pain participated in the present study. They were selected randomly from" the national institute of urology and nephrology". Their ages ranged from 40 to 65 years old& they had the following criteria: were eligible for enrollment in the study; complain from pelvic pain persisted more than 3 months, &conscious. All patients were male ,They have no pacemaker. non diabetic with no history of chronic relevant medical disease. Patients were excluded if they had life threatening disorders as renal failure, myocardial infarction, active malignancy , myasthenia gravis, hyperthyroidism, hemorrhage, acute viral diseases, acute tuberculosis, mental disorders , soft tissue infection or cellulites. Patients then were classified randomly into two equal groups.

Group I: consisted of twenty five patients who were treated by electrical stimulation of the posterior tibial nerve stimulation (PTNS) plus the traditional medical program. The procedure for PTNS consisted insertion of the needle above the medial malleouls into the posterior tibial nerve followed by the application of low voltage (10 MA 1-10 Hz frequency and a fixed pulse duration (200 microsecond) electrical stimulation which produce sensory and motor responses (i.e. tickling sensation and planter flexion or fanning of all toes). PTNS studies had been designed as 15-minute sessions given 3 times per week for 10-12 weeks (10).

Group II: consisted of twenty five patients who received placebo electrical stimulation plus the traditional medical program.

Equipment:

-Therapeutic equipment: Electrical stimulator unit: Sonopulse- 992(ENRAF NONIU); made in Holland by Dimeq Bu,was used to inhibit the involuntary detrusor muscle contractions. The biphasic rectangular pulse in the Sono-pulse used for the treatment of chronic pelvic pain The system does not cause any unpleasant sensation for the patient and could be used for longer period of stimulation. Electrical stimulation delivered to the posterior tibial nerve via a combination of electrode and generator components, including a, surface electrodes, lead wires and hand held electrical generator. The low-voltage stimulator (9 volts) had an adjustable pulse intensity of 0-10mA, a fixed pulse width of 200 microseconds and a frequency of 10Hz. The device produces an adjustable electrical impulse that travels to the sacral nerve plexus via the tibial nerve (11).

Measuring equipment:

1- Visual analogue scale (VAS) 2- Tools for measuring McGill Pain Questionnaire.

Procedures of the study: The experimental protocol explained in details for every patient before starting the initial assessment, and a written consent form signed by each patient before starting treatment. The treated patients instructed to report any side effects during the treatment sessions.

1) Therapeutic Procedures:

A-Group I (study group): All subjects in this group received their medical treatment& then asked to evacuate their bladder before starting the treatment sessions to ensure that they are relaxed and comfortable during the session. With the patient sitting in frog –leg position with the soles of the feet touching and the knee flexed. The medial aspect of the lower extremities was palpated and sensitive pressure point was identified approximately three fingers breadth posterior from the edge of the tibia. A 34 gauge, solid stainless steel needle was advanced through the skin with the aid of an overlying plastic cylinder that was 3 mm, shorter than the needle. Once the skin was pierced the cylinder was removed, and the needle was advanced approximately 3-4 cm posterior to the tibia. The needle trajectory was 60 degrees cephaled from a perpendicular line along the length of tibia and advanced toward the patients head. An electrocardiogram ground pad electrode was placed over the medial aspect of the calcaneus. A stimulator was then connected to the needle and the ipsilateral ground pad electrode. Proper needle placement was confirmed with the great toe flexion and fanning or toe flexion of ipsilateral digits 2 through 5 (10).

B- Group II (Control Group): All subjects in this group received placebo electrical stimulation plus the traditional medical program .

2- Measurement procedure:

Pain measurement: I-visual analogue scale (VAS): Pain can only be measured subjectively. The most reliable and well-understood method is a numerical rating Scale, from 0 (no pain) to 10 (extreme pain), with half-points marked (11).

II-The McGill Pain Questionnaire: Also known as McGill pain index is a scale of rating pain developed at McGill University by Melzack and Torgerson in 1971.To use the questionnaire, circle the words that describe your pain but do not circle more than one word in a group. Then when you have that done, go back and circle the three words in groups 1-10 that most convey your pain response. Pick the two words in groups 11-15 that do the same thing. Then pick one word in group 16. Finally, pick 1 word in groups 17-20. At the end you should have seven words that you can take to your doctor that will help describe both the quality of your pain and the intensity of it. Descriptive statistics (the mean and the standard deviation) were calculated for all patients (control group and treatment groups).

Statistcal procedures:The mean and standard deviation was used as a kind of central tendency to describe a group of individuals with single measurement (descriptive statistics). Paired "t" test was used to compare the results pre and after treatment in the same group for each group, with level of significance (≤0.05) (12).

Results:

1- The results of the current study revealed that there was non-significant difference in the mean values of age between both groups of the study.

2- The results of VAS pre treatment: The mean value of VAS pre-treatment for study group was 6.84 ± 0.8 & for control group was 6.92± 0.81,the mean difference between both groups was 0.08 there was no statistical significance difference between both groups pre treatment p=(0.72). (Table 1, Fig1)

3- The results of VAS post treatment: The mean value of VAS post-treatment for study group was 3.96 ± 1.06 & for control group was 6.44± 0.71,the mean difference between both groups was 2.48 there was highly statistical significance difference between both groups post treatment p=(0.0001). (Table 1, Fig1)

Table(1) Comparison pre and post values of VAS between both groups control& study

Item / Pre- treatment / Post- treatment
Control / Study / Control / Study
x̅ / 6.92 / 6.84 / 6.44 / 3.96
±SD / 0.81 / 0.8 / 0.71 / 1.06
MD / 0.08 / 2.48
T-value / 0.35 / 9.71
p- value / 0.72 / 0.0001
Level of significance / NS / Highly significant

X= mean SD=standard deviation Ns=non significance

Fig(1) Comparison pre and post values of VAS between both groups control& study

4-Results of McGill Pain Questionnaire pre treatment : The mean value McGill Pain Questionnaire of pre-treatment for study group was 47.96 ± 5.31 & for control group was 48.56± 5.29,the mean difference between both groups was 0.6 there was no statistical significance difference between both groups pre treatment p=(0.69). (Table 2, Fig2)

5-Results of McGill Pain Questionnaire post treatment : The mean value McGill Pain Questionnaire of post-treatment for study group was 28.28 ± 5.0 & for control group was 46.48± 4.5,the mean difference between both groups was 18.2 there was highly statistical significance difference between both groups post treatment p=(0.0001). (Table 2, Fig2)

Table (2): comparison of pre &post values of McGill Questionnaire score between both groups.

Item / Pre- treatment / Post- treatment
Control / Study / Control / Study
x̅ / 48.56 / 47.96 / 46.48 / 28.28
±SD / 5.29 / 5.31 / 4.5 / 5.0
MD / 0.6 / 18.20
T-value / 0.4 / 13.47
p- value / 0.69 / 0.0001
Level of significance / NS / Highly significant

X= mean SD=standard deviation Ns=non significance

Fig (2) comparison of pre &post values of McGill Questionnaire score

Discussion: Chronic pelvic pain is a common problem with a high impact on patients’ quality of life. Unfortunately, pelvic pain is hard to measure, assess or localize, causing great difficulties in diagnosis and treatment (1).

Transcutaneous electrical nerve stimulation (TENS) was introduced as an alternatively therapy to pharmacological treatments for chronic pain. TENS currently is one of the most commonly used forms of electro analgesia. Hundreds of clinical reports exist concerning the use of TENS for various types of conditions such as low back pain, myofascial and arthritic pain, sympathetically mediated pain, neurogenic pain, visceral pain, and post-surgical pain (13,14).This study was conducted to investigate the efficacy of posterior tibial nerve electrical stimulation on chronic pelvic pain syndrome. In this study the patients were randomly divided into two equal groups; each group included twenty five patients. the result of this study was as the following there was non-significant difference in the mean values of age between both groups of the study (control and study groups).There was no significant difference between both groups (control and study) in mean values of VAS pre-treatment. also showed that VAS has highly significant decrease after 12 weeks of application of electrical stimulation in the study group when compared with placebo effect in the control group &There was no significant difference between both groups in mean values of McGill Pain Questionnaire score pre-treatment. The McGill Pain Questionnaire score has highly significant decrease after 12 weeks of application of electrical stimulation in the study group when compared with placebo effect in the control group.

Therefore the results of the current study showed no significant difference between the electrical stimulation group and the control group pre treatment for; VAS and McGill Pain Questionnaire scores. And a highly significant difference between the electrical stimulation group and the control group post treatment for; VAS and McGill Pain Questionnaire scores.

Percutaneous tibial nerve stimulation (PTNS) is one of the least invasive forms of neurostimulation, since posterior tibial nerve shares the sacral roots with bladder afferent it is currently used for a variety of urologic conditions including interstitial cystitis, incontinence, chronic pelvic pain and overactive bladder (OAB)(15).

Percutaneous tibial nerve stimulation is a mixed nerve containing sensory and motor nerve fibers .Correct placement of the needle electrode induce a motor and sensory response centrally the PTN project to the sacral spinal cord in the same area where the bladder projection are found.(i.e. the sacral micturation centre and the nucleus of Onuf) these are most probably the area where the therapeutically effect of neuromodulation of the bladder through posterior tibial nerve stimulation take place (16) .

PTNS was introduced as a peripheral form of SNS, aiming at simplicity and less invasiveness than the latter. When applied in the treatment of urinary tract dysfunction e.g urinary frequency, urgency and incontinence, PTNS produces more than 50% improvement in 70% of patients. The pain and urodynamic improvement were also reported in patients with an overactive bladder(16,10).

Electrical stimulation is an effective and a safer modality in the treatment of bladder dysfunction, therefore electrical stimulation was strongly recommended in this study due to its low cost if compared to other modalities, easy application, and good results(17). it was approved that a biphasic, continuous pulse with a pulse width of 200 microseconds excites muscle fibers at a relatively low current intensity, and this is more comfortable than shorter pulse widths, which may require current intensity high enough to be perceived as painful before a tetanic muscle contraction is produced, in electrically stimulated muscle the recruitment is reversed, with type II fibers being recruited first(18).

The results of this study were supported by the work reported by Payne 2000, Vanbalken etal., 2003 ,Vanderbal etal., 2006, Wooldridge 2009, Vandonink etal., 2004, Degeneroetal., 2004, Hobeke etal., 2002, Carol etal., 2001, Cao etal., 2007, Govier etal., 2001, Klinger etal., 2000, Kim etal., 2007 (19,10,6,20,21,22,23,16,17,24,25,26,27,28):

PTNS efficacy is studied by several groups. In 1998, Payne published on a statistically significant improvement in 98 patients with frequency, incontinence and pelvic pain(19).

PTNS requires further research to determine optimal stimulation parameters and to analyze predictive factors(10).

The effect of PTNS on patients with chronic pelvic pain (Cpp), a painful bladder condition associated with urinary urgency and frequency, which is often resistant to medication and physical therapy. In one study, done in Beijing, there were significant improvements in symptomatology after treatment with PTNS. Nighttime bladder volume, chronic pelvic pain Problem Index score, and health status scores all showed improvement(6).

Percutaneous tibial nerve stimulation has been investigated for the treatment of chronic pelvic pain in persons who have failed conservative treatments (20).

Additional studies conducted assessed patients (n=35 to 39) treated with PTNS and concluded that PTNS is an effective, minimally invasive procedure to treat pain and idiopathic voiding dysfunction (21).

PTNS and pain in 23 children with lower urinary tract symptoms is safe and minimally painful in children (22).

This is in agreement with a study of 32 children that reported that PTNS has a significant effect on voiding frequency, bladder capacity, and uroflowmetry curve in children with bladder sphincter dysfunction (23).

The widespread use of TENS is useful for a wide range of chronic pain conditions (24,16).