Neuromodulation for Chronic Pelvic Pain: A Single-Institution Experience With a Collaborative Team

Abstract

BACKGROUND

Secondary to the complex care, involved specialty providers, and various etiologies, chronic pelvic pain patients do not receive holistic care.

OBJECTIVE

To compare our general and neuromodulation cohorts based on referrals, diagnosis, and therapy and describe our neuromodulation patients.

METHODS

A multidisciplinary team was established at our center. The intake coordinator assessed demographics and facilitated care of enrolled patients. Outcomes were compared using minimal clinical important difference of current Numerical Rating Scale (NRS) between patients with neuropathic pain who received neuromodulation and those who did not. The neuromodulation cohort completed outcome metrics at baseline and recent follow-up, including NRS score (best, worst, and current), Oswestry Disability Index (ODI), Beck Depression Inventory, and Pain Catastrophizing Scale.

RESULTS

Over 7 yr, 233 patients were referred to our consortium and 153 were enrolled. A total of 55 patients had neuropathic pain and 44 of those were managed medically. Eleven underwent neuromodulation. A total of 45.5% patients of the neuromodulation cohort were classified as responders by minimal clinically important difference compared to 26.6% responders in the control cohort at most recent follow-up (median 25 and 33 mo, respectively). Outcome measures revealed improvement in NRS at worst (P = .007) and best (P = .025), ODI (P = .014), and Pain Catastrophizing Scale Rumination (P = .043).

CONCLUSION

Eleven percent of patients were offered neuromodulation. There were more responders in the neuromodulation cohort than the conservatively managed neuropathic pain cohort. Neuromodulation patients showed significant improvement at 29 mo in NRS best and worst pain, disability, and rumination. We share our algorithm for patient management.

Graphical Abstract

Graphical Abstract.

ABBREVIATIONS

BDI

Beck Depression Inventory

CPP

chronic pelvic pain

CS

central sensitization

DRG

dorsal root ganglion

GABA

gamma-Aminobutyric acid

HF

high frequency

ITP

intrathecal pain pump

IVIG

intravenous immunoglobulin

MCID

minimal clinically important difference

MPQ

McGill Pain Questionnaire

NRS

Numerical Rating Scale

ODI

Oswestry Disability Index

PCS

Pain Catastrophizing Scale

PM&R

physical medicine and rehabilitation

PT

physical therapy

SCS

spinal cord stimulation

TCA

tricyclic antidepressant

Chronic pelvic pain (CPP) is a debilitating condition impacting 14% of individuals worldwide.¹ CPP poses a significant financial burden on the US healthcare system, costing upward of $800 000 000.² CPP is symptomatically characterized by intensity, region, and presence of urinary or sexual dysfunction. The etiology of CPP is multifactorial, involving gynecologic, gastrointestinal, urologic, musculoskeletal, and psychiatric disorders leading to a diminished quality of life among patients and caregivers. Secondary to the complexity of care and number of involved specialty providers, CPP patients are often underdiagnosed, underserved, and do not receive holistic care. Studies show a coordinated multidisciplinary approach to pain management provides more stable and efficacious pain improvement compared to single-discipline treatments.² Neuropathic pain in CPP is often managed with physical therapy (PT), pudendal nerve blocks, botulinum-toxin injection, and medications including tricyclic antidepressants (TCAs), anticonvulsants, and anti-inflammatories. However, many patients’ pain remains refractory to treatment.

Neuromodulation is developing an emerging role in CPP management, providing options such as spinal cord stimulation (SCS), dorsal root ganglion (DRG) stimulation, and intrathecal pain pumps (ITPs).³ Sacral neuromodulation aids patients with medically refractory bladder pain syndrome.³ DRG stimulation provided a 43% reduction in pelvic girdle pain at 6-mo follow-up.⁴ A prospective study showed 74% of refractory CPP patients receiving SCS experienced over 50% improvement in pain.⁵ Overall, these studies suggest that neuromodulation has demonstrated significant strides in CPP management, but warrants continued investigation.

Objectives

We developed a multidisciplinary team at Albany Medical Center to effectively analyze and optimize the care of the enrolled CPP patient population. We aim to compare our general and neuromodulation cohorts based on referrals, subtype(s) of pelvic pain diagnosis, and therapeutic strategies. Additionally, we aim to appropriately describe our neuromodulation patients.

METHODS

Setting

A multidisciplinary team for CPP treatment was established at Albany Medical Center, consisting of specialists in neurosurgery, neurology, pain management, physical medicine and rehabilitation (PM&R), urology, gynecology, general surgery, addiction counseling, psychology, and psychiatry.

Study Design

Treating physicians were provided contact information for the consortium. A treating physician made the referral and the patient was then contacted with an intake form by our consortium coordinator (Table 1). The coordinator used this information to discuss the patient with the program's director (senior author J.P.). The program director determined which referrals to make and whether to perform those in parallel or series based on symptoms. Generally, pelvic-floor PT was completed prior to other referrals if the patient had previous pelvic pain treatment. If the patient was new to the consortium, a specialist physician was the first referral based on the predominant symptoms. Further determinations were made accordingly (Figure 1A and 1B). All patients were offered participation in an Institutional Review Board approved outcome study.

TABLE 1.

Intake Questionnaire

Symptoms associated with pelvic pain: (Please CIRCLE all that apply)	Do you have these symptoms?	We may refer you to:	Do you have a doctor for this?
Bladder symptoms: urinary frequency, urgency, difficulty emptying, leakage, frequent urinary tract infections, or blood in urine?	Yes ■ No ■	Urology female pelvic medicine and reconstructive surgery	Yes ■ No ■ Name: ____________
Vaginal discharge or infection, endometriosis, pain worse with periods, recurrent ovarian cysts, or vaginal bleeding after menopause?	Yes ■ No ■	Gynecology	Yes ■ No ■ Name: ____________
Pain with intercourse or sexual activity?	Yes ■ No ■	Urology or gynecology female pelvic medicine and reconstructive surgery	Yes ■ No ■ Name: ____________
Bulge coming out of the vagina? Vaginal mesh eroding in the vagina?	Yes ■ No ■	Urology or gynecology female pelvic medicine and reconstructive surgery	Yes ■ No ■ Name: ____________
Bowel incontinence (loss of control of stool) or severe constipation?	Yes ■ No ■	Colorectal surgery	Yes ■ No ■ Name: ____________
Numbness, tingling, or altered sensation in feet or privates, balance problems, weakness in the arms or legs, vision changes?	Yes ■ No ■	Neurology or PM&R	Yes ■ No ■ Name: ____________
Depression or anxiety symptoms impacting life? History of physical or sexual abuse/trauma? Lack of support, trouble managing life, or feeling hopeless or a loss of control?	Yes ■ No ■	Psychology or psychiatry for management of medical stressors	Yes ■ No ■ Name: ____________
Is there dependence on any medications, alcohol, or drugs? Ever tried to cut down without success?	Yes ■ No ■	Addiction counseling	Yes ■ No ■ Name: ____________

FIGURE 1.

A and B, Study participants’ flowcharts. A, Overall cohort referral patient breakdown. B, Neurosurgery referral patient breakdown. *Most patients received more than one referral (n = 98).

Participants

After providing informed consent, demographic data were collected on enrolled patients, including age, sex, pain duration, pelvic pain diagnosis, subspecialty referrals, and types of therapeutic interventions.

Data Sources

Patients who underwent neuromodulation completed outcome measure assessments during preoperative and postoperative follow-up. Outcome measures included Numerical Rating Scale (NRS), Oswestry Disability Index (ODI), McGill Pain Questionnaire (MPQ), Beck Depression Inventory (BDI), and Pain Catastrophizing Scale (PCS). ODI assesses patient disability with a higher score indicating more severe disability.^6,7 PCS measures the cognitive aspect of pain in 3 categories: rumination, magnification, and helplessness.⁸ A higher score indicates worse impairment. MPQ assesses affective and sensory pain with a higher score indicating more pain.⁹ BDI assesses the severity of depressive symptoms with a higher score indicating more depression.¹⁰ NRS scores were determined at best of week, worst of week, and current time.

Variables

Patients in the comparator group only had current NRS available. Thus, we utilized minimal clinically important difference (MCID) of current NRS as the primary outcome. MCID is defined as a 1.2-point improvement in NRS.¹¹ Percentage of patients who achieved MCID at latest follow-up was determined for each group. Pain relief was assessed by comparing outcome measures at baseline and latest follow-up (median 33 mo in neuropathic pain; 25 mo in neuromodulation cohort).

Statistical Analysis

Demographic and treatment data were obtained for enrolled patients. Chi-square, Fisher's exact, and unpaired t-tests were used to compare cohorts. MCID and difference in current NRS scores were assessed between neuropathic pain and neuromodulation groups. For secondary outcome metrics only available in neuromodulation groups, the degree of change was determined. Data were analyzed with IBM SPSS Statistics 22.0 (IBM, Armonk, New York) and GraphPad Prism 8 (GraphPad Software, San Diego, California). A P-value less than .05 was considered statistically significant.

RESULTS

General Cohort: Participants and Descriptive Data

Over a 7-yr period, 233 patients were referred and 153 were enrolled (84% women; mean age 45 (21-94 yr)). The mean duration of pain before diagnosis was 5.92 ± 0.54 yr (± standard error of the mean). The most common etiologies of CPP included the following: pelvic-floor dysfunction (14.4%), neuropathic pain of unknown etiology (13.7%), dyspareunia (11.1%), endometriosis (9.2%), small-fiber neuropathy (8.5%), painful bladder syndrome (7.2%), and pudendal neuralgia (5.9%) (Table 2). Of the 153 patients, 73% of patients trialed 3 or more medications. The percentage distribution of patients who trialed specific medications was as follows: selective serotonin reuptake inhibitor (20%), serotonin-norepinephrine reuptake inhibitor (58.2%), TCA (27.3%), gamma-Aminobutyric acid (GABA) analogues (gabapentin, pregabalin; 62%), opioids (40%), antibiotics/antifungals (24%), muscle relaxants (44%), bladder relaxants (29%), hormone therapy (25%), and antiepileptics (15%).

TABLE 2.

Demographics

Characteristics	Total cohort (n = 153)	Neuropathic pain without neuromodulation (n = 44)	Neuromodulation cohort (n = 11)
Age (range)	45 (21-94)	47 (23-76)	49 (26-78)
Female, male	129, 24	37, 7	9, 2
Years of pain before diagnosis	5.92 ± 0.54	7.31 ± 1.08	9.95 ± 2.33
Pelvic floor dysfunction	22 (14.4%)	0 (0%)	0 (0%)
Neuropathic pain (unknown etiology)	21 (13.7%)	15 (34%)	6 (55%)
Dyspareunia	17 (11.1%)	2 (5%)	0 (0%)
Endometriosis	14 (9.2%)	0 (0%)	0 (0%)
Small-fiber neuropathy	13 (8.5%)	11 (25%)	2 (18%)
Painful bladder syndrome	11 (7.2%)	0 (0%)	0 (0%)
Pudendal neuralgia	9 (5.9%)	6 (14%)	1 (9%)
Pelvic pain NOS	8 (5.2%)	0 (0%)	0 (0%)
Vulvodynia	5 (3.3%)	3 (7%)	0 (0%)
Testicular pain	5 (3.3%)	1 (2%)	0 (0%)
Ovarian cysts	4 (2.6%)	0 (0%)	0 (0%)
Dysuria	3 (2%)	0 (0%)	0 (0%)
Rectocele	3 (2%)	0 (0%)	0 (0%)
Fibromyalgia	3 (2%)	3 (7%)	0 (0%)
Penile pain	3 (2%)	1 (2%)	2 (18%)
Coccydynia	2 (1.3%)	0 (0%)	0 (0%)
Leiomyomas	2 (1.3%)	0 (0%)	0 (0%)
Vaginitis	1 (0.7%)	0 (0%)	0 (0%)
Rectovaginal fistula	1 (0.7%)	0 (0%)	0 (0%)
Enterocutaneous fistula	1 (0.7%)	0 (0%)	0 (0%)
Bladder prolapse	1 (0.7%)	0 (0%)	0 (0%)
Erosion of vaginal mesh	1 (0.7%)	0 (0%)	0 (0%)
Chronic inflammatory demyelinating polyneuropathy	1 (0.7%)	1 (2%)	0 (%)
Nephrolithiasis	1 (0.7%)	0 (0%)	0 (0%)
Ejaculatory pain	1 (0.7%)	1 (2%)	0 (0%)

A total of 15 of 153 patients did not pursue care after their initial visit (Table 3). A total of 7 of these 15 independently worked with psychiatry. Of the remaining 138 patients, 98 were referred to PT (64.1%), 57 to gynecology (37.3%), 54 to urology (35.3%), 52 to psychiatry (34%), 49 to neurology (32%), 35 to pain management including PM&R (22.9%), 25 to functional neurosurgery (16.3%), 21 to colorectal surgery (13.7%), and 6 to general surgery (3.9%) (Table 3). Most patients received more than one referral (64.1%).

TABLE 3.

Breakdown of Referrals

Referrals	Men	Women	%Total (n = 153)
PT	16	82	98 (64.1%)
Psychiatry/psychology	13	46	59 (38.6%)
Obstetrics and gynecology	1	56	57 (37.3%)
Urology	13	41	54 (35.3%)
Neurology	9	40	49 (32.0%)
Pain management	5	30	35 (22.9%)
Neurosurgery	5	20	25 (16.3%)
Colorectal surgery	7	14	21 (13.7%)
No referrals	3	12	15 (9.87%)
General surgery	1	5	6 (3.9%)

Neuropathic Pain Cohort Managed Without Neuromodulation: Participants and Descriptive Data

A total of 55 patients had a neuropathic component to their pain. A total of 16 were referred to functional neurosurgery, 34 to neurology, 28 to PT, 23 to psychiatry, and 22 to PMR. A total of 74.5% of patients trialed 3 or more medications. The percentage distribution of patients who trialed-specific medications was: antidepressants (55%), GABA analogues (62%), opioids (40%), antibiotics/antifungals (24%), muscle-relaxants (44%), bladder-relaxants (29%), hormone therapy (25%), and antiepileptics (15%). A total of 7 patients underwent pudendal nerve block (4.6%), 13 epidural-steroid injections (8.5%), 10 botulinum-toxin (6.5%), 3 IV-lidocaine infusions (2.0%), 1 radiofrequency ablation (0.7%), and 1 intravenous immunoglobulin (IVIG) infusion (0.7%) (Table 4).

TABLE 4.

Breakdown of Therapies by Diagnosis

	Neuropathic pain (n = 21)	Small fiber neuropathy (n = 13)	Pudendal neuralgia (n = 9)	Fibromyalgia (n = 3)	Vulvodynia (n = 3)	Dyspareunia (n = 2)	Testicular pain (n = 1)	Penile pain (n = 1)	Ejaculatory pain (n = 1)	CIDPa (n = 1)
Referrals
PT	71.4%	61.5%	55.6%	66.7%	66.7%	100%	100%	0%	0%	100%
Functional neurosurgery	33.3%	15.4%	55.6%	33.3%	0%	0%	100%	0%	0%	0%
Neurology	33.3%	92.3%	66.7%	66.7%	33.3%	100%	0%	100%	100%	100%
Injections
Pudendal nerve block	9.5%	0%	44.4%	33.3%	0%	0%	0%	0%	0%	0%
Botox injection	23.8%	23.1%	22.2%	0%	33.3%	0%	0%	0%	0%	0%
ESI	28.6%	15.4%	33.3%	0%	33.3%	0%	100%	0%	0%	0%
Radiofrequency ablation	4.8%	0%	0%	0%	0%	0%	0%	0%	0%	0%
IV lidocaine	4.8%	7.7%	0%	33.3%	0%	0%	0%	0%	0%	0%
IVIG Infusion	0%	0%	0%	0%	0%	0%	0%	0%	0%	100%
Medications
Antidepressants	42.9%	53.8%	77.8%	100%	66.7%	50%	0%	0%	0%	100%
GABA analog	42.9%	76.9%	77.8%	100%	100%	50%	0%	100%	0%	0%
Opioids	28.6%	46.2%	55.6%	100%	33.3%	0%	0%	0%	100%	0%
Antibiotic/antifungal	33.3%	30.7%	11.1%	33.3%	0%	0%	0%	0%	0%	0%
Muscle relaxant	33.3%	53.8%	55.6%	66.7%	33.3%	0%	0%	0%	100%	100%
Bladder relaxant	38%	23.1%	11.1%	66.7%	0%	0%	0%	0%	0%	0%

Percentages represent therapies trialed by diagnosis where (n) is the denominator.

^aCIDP: Chronic Inflammatory Demyelinating Polyneuropathy.

Neuromodulation Cohort: Participants and Descriptive Data

A total of 11 of the 25 patients referred to functional neurosurgery underwent neuromodulation (91% women; mean age 49 (range 26-78 yr) (Table 2). Of the 14 other referrals, neuromodulation was recommended for 5, but the patients opted not to proceed with a trial, and 9 were not candidates (Table 4). Specifically, 8 had a major spine component to their pain and were managed accordingly and 1 had diffuse axial pain and was managed with rheumatology. Diagnoses were neuropathic pain (n = 6), small-fiber neuropathy (n = 2), penile pain (n = 2), and pudendal neuralgia (n = 1). A total of 8 of these 11 patients received single-modality treatment and 3 received multimodality neuromodulation (Table 5). A total of 4 of these 8 patients had SCS alone (2 high-frequency (HF), 2 retrograde-tonic systems), 3 underwent DRG stimulation, and 1 had an ITP with ziconotide. One of the multimodality patients had SCS (both retrograde-tonic and HF), ITP, and a DRG trial. Another had suboptimal control retrograde for both SCS and DRG. The final went on to HF-stimulation after DRG stimulation. One patient had complete resolution of pain with DRG stimulation and the device was explanted after a year of being pain-free.

TABLE 5.

Neuromodulation Cohort Stimulation Parameters

Patient #	Indication	SCS placement	DRG lead placement	Pump catheter placement	Stimulation parameters	MCID	Outcome
1	Postherpetic neuralgia	L5-S1 paddle	–	–	Subparesthesia, occasional use of tonic (3x/week)	0	Nonresponder
2	Neuralgia and neuritis	T8-9 paddle; S1-3 single percutaneous	–	–	Tonic	−1	Nonresponder
3	Neuropathic pain	T8-10 dual percutaneous	–	–	HF-10	1	Nonresponder
4	Small fiber polyneuropathy, fibromyalgia	T9-12 dual percutaneous	–	–	HF-10	−1	Nonresponder
5	Small-fiber neuropathy	T11-T12 paddle	Bilateral L1 and S1 failed	–	HF-10, occasional use of tonic pairing	2	Responder
6	Neuropathic pain	T8-11 dual percutaneous; S1-3 dual percutaneous failed	Bilateral L1 and S2 failed trial	T7, Ziconotide 2.3 mcg/day	HF-10	0	Nonresponder
7	Penile pain	T12-L1 single percutaneous failed; S1-3 paddle/percutaneous failed	Bilateral L1 and S3	–	Subparesthesia	5	Responder
8	Painful bladder syndrome	L5-S1 paddle failed	Bilateral L1 and S2	–	Subparesthesia	7	Responder
9	Penile pain	–	Left L1, L2, S2 complete remission and explanted	–		7	Responder
10	Neuropathic pain	–	Bilateral T11, left T12 and right L2	–	Subparesthesia	2	Responder
	Neuropathic pain	–	–	T8, hydromorphone 2.8 mg/day		−3	Nonresponder

Comparison of demographics between the patients offered neuromodulation and the general cohort revealed a significant difference in age (52.8 ± 4.0 v. 43.6 ± 1.3; P = .02), but no significant difference in sex (P = .279) or pain duration since diagnosis (P = .2562). Patients offered neuromodulation were more likely to have neuropathic pain (P < .001).

Outcome Data and Main Results

We next analyzed groups with neuropathic pain, comparing those that underwent neuromodulation and those that did not. There were 44 neuropathic pain patients without neuromodulation with median latest follow-up of 33 mo (range 2-96 mo). There was no change between baseline (4.42 ± 0.44; n = 38) and at latest follow-up NRS (3.81 ± 0.45; n = 32) (P = .462). A total of 8 patients were classified as responders, 22 were nonresponders, and 14 had insufficient data to determine the MCID. Thus, 8/30 (26.6%) patients were responders.

The neuromodulation cohort (n = 11) had a median follow-up of 25 mo (range 2-36 mo). Baseline NRS was 6.63 ± 0.45 and NRS at follow-up was 4.91 ± 0.93 (P = .11). A total of 5 of 11 (45.5%) patients were responders. Responders and nonresponders did not differ in age (P = .955) or sex (P = .147).

Among secondary outcomes in our neuromodulation cohort, there were significant improvements in NRS-worst (P = .007) (Figure 2A), NRS-best (P = .025) (Figure 2B), ODI (P = .014) (Figure 2C), and PCS-rumination (P = .043) (Figure 2D). Improvement in BDI (P = .064) approached significance. No improvement was seen in other measures: NRS-current, NRS-average, PCS-total, PCS-Helplessness, PCS-Magnification, MPQ-Total, MPQ-Sensory, and MPQ-Affective (P > .500).

FIGURE 2.

A-D, Pain outcome measure assessment from baseline to latest follow-up. A, There was statistically significant improvement in NRS score at patients’ worst rated pain (P = .007). B, There was statistically significant improvement in NRS score at patients’ best during the week (P = .025). C, There was significant improvement in ODI (P = .014). D, There was significant improvement in PCS-rumination (P = .043). [*P < .05]

DISCUSSION

Key Results

We report our experience with the development of a multidisciplinary team focused on the treatment of CPP patients. We found that the most common diagnoses were pelvic-floor dysfunction, neuropathic pain of various etiologies and painful bladder syndrome. A total of 11.5% of patients were candidates for neuromodulation. More neuropathic pain patients did well in the neuromodulation group (45.5%) compared to the no-neuromodulation group (26.6%). Secondary outcomes revealed improvement in the neuromodulation cohort in NRS-worst and best-pain, ODI, and PCS-rumination. We attempted to further differentiate these data into responders and non-responders, but the subset was too small for meaningful analysis.

Interpretation

The pathophysiology of CPP is poorly understood. There are 3 theories to describe the origin of CPP: nociceptive, inflammatory, and neuropathic.¹² Nociceptive pain is described as diffuse pain occurring at dermatomes supplied by autonomic innervation of the affected viscera. It can be caused by inflammation, distension, or hemorrhage. Inflammatory mechanisms of CPP are associated with inflammatory mediators and the cross-sensitization phenomenon. This phenomenon hypothesizes that stimulation and inflammation of one organ causes congruent stimulation of local structures supplied by the same DRG. This “cross-talk” consequently leads to propagation of pain perception and organ dysfunction as manifested in the overlap of CPP disorders.¹³ Additionally, inflammatory mediators such as tumor necrosis factor alpha, nerve growth factor, prostaglandins, and interleukins have been implicated in CPP pain perception.¹² Neuropathic pain occurs secondary to injury to the central or peripheral nervous system. Specifically, central sensitization (CS) has been implicated in CPP.¹⁴ CS refers to central nervous system dysfunction leading to sustained hypersensitivity of painful signaling despite removal of painful stimuli, manifesting as allodynia, trigger points, and lower pain thresholds.¹²

Unfortunately, there is no literature on the natural history of neuropathic pelvic pain. There is some literature on one subset of patients with pudendal neuralgia. Due to effects on quality-of-life,^15,16 there are no known studies indicating whether pudendal neuralgia resolves itself without treatment. In some cases, simply stopping the pain-inducing activity may offer relief while, in more severe cases, injections, decompression surgery, or pulsed-radiofrequency are required.¹⁵ However, several studies evaluating these different treatments report only short-term relief, if any.^16,17 While the best intervention for pudendal neuralgia has yet to be determined,^18,19 correct diagnosis and treatment are necessary to relieve symptoms.

Neuromodulation is successful in treating CPP with a neuropathic component.^18,19 A prospective-nonrandomized study in patients with intractable CPP demonstrated greater than 40% improvement in pain, specifically reducing visual analog scale scores at 6-mo follow-up.²⁰ DRG stimulation is theorized to provide pain relief through hyperpolarization of somatic action potentials and suppression of ectopic activity.²¹ A multicenter study of DRG stimulation for patients with postherniorrhaphy pain showed greater than 50% pain reduction at latest follow-up.²² Case series on focal bilateral L1 and S2 DRG stimulation for CPP patients demonstrated satisfaction, reduced opioid consumption, 70% to 90% improvement in NRS by 3-mo follow-up, and improvement in ODI and NRS by 18-mo follow-up.²³ Overall, these studies support the emerging role of neuromodulation in sustained and reproducible pain relief among CPP patients.

CPP is a complex condition with somatic and psychological implications, necessitating multidisciplinary involvement to effectively diagnose and provide targeted therapy. Various studies have reported improvement in chronic pain through utilization of multidisciplinary care teams. A meta-analysis of 65 studies reported that multidisciplinary pain treatment was associated with improvements in pain control, emotional response, return to work, and decreased use of healthcare-system compared to single-discipline, wait-listed, and no-discipline care regimens.^2,24

Generalizability

We demonstrate our experience with a multidisciplinary consortium. Neuromodulation patients had improved outcomes in NRS compared to the neuropathic patients not treated with neuromodulation. This finding is essential in CPP management. First, these patients are often dramatically underserved. While most chronic pain patients suffer for 2 yr, CPP patients suffer for upwards of 5 yr prior to treatment with a specialist.^25,26 Second, there remains a stigma surrounding people, mostly women, with this condition. Psychological issues are common with all types of pain, but providers often focus on psychological rather than physical components of CPP. We concur that all pain patients should be psychologically optimized. However, we note that the duration of disease prior to treatment and the loss of trust that these patients feel with their support and healthcare-networks concomitantly impact patients’ psychological status.²⁷

Despite the potential for neuromodulation in these patients, experts in the field have concerns that pain physicians/functional neurosurgeons lack training in how to effectively deliver long-term care to CPP patients. Specifically, neuromodulators and associated care teams often do not have the training or comfort to conduct a thorough pelvic exam or certain procedures, such as a pudendal nerve block.²⁸ Medical management, pelvic-floor PT, and/or injections should be performed prior to considering neuromodulation. It is essential to develop a care team where all the patients’ needs may be met. By connecting the specialties crucial to CPP management, providers can rely on the expertise of these specialties, while patients gain access to a robust and targeted treatment armamentarium. Following neuromodulation, it is essential to revisit the multidisciplinary clinic team to augment responses, similarly to procedural management of SCS patients for back and leg pain. We provided our algorithm and data to further educate providers and subsequently enhance the care of CPP patients.

Limitations

We are aware that this study contains limitations, including the subjective nature of pain questionnaires and heterogeneity within our study population. Pain questionnaires ask patients to evaluate pain intensity over time, thereby introducing minimal recall bias as time from surgery increases. A larger sample size may reduce heterogeneity and elucidate correlations that did not emerge within the investigation. Future studies will involve expansion of our study population, standardization of post-operative evaluation, and continued collection of neuromodulation outcome measure data. Additionally, 55 patients had neuropathic pain and only 34 were referred to neurology. Sixteen of the 34 were referred to functional neurosurgery. As 75% of these patients had trialed 3 or more medications for treatment of their pain, it seems that neuromodulation was potentially underutilized. We will alter our algorithm moving forward to ensure that all patients with a neuropathic component of pain are seen by neurology and after failure of a minimum of 2 therapies are discussed at a multidisciplinary committee for consideration of neuromodulation. A final limitation is the lack of knowledge about the natural history of pelvic pain. Limited data on similar pain conditions, such as pudendal neuralgia, suggest that some form of medical management is necessary to moderate pain. Future studies should attempt to investigate the natural history of pelvic pain, however, as pain severely affects patients’ quality of life, such studies may be challenging.

CONCLUSION

Secondary to the complexity of CPP diagnosis and management, patients do not receive holistic care. We present our experience with a multidisciplinary pelvic pain consortium. Our study is the first to assess the incidence of neuropathic pain in such a consortium and describe management of those patients. We also present our initial experience with neuromodulation of neuropathic pain patients whose pain was refractory to other treatments. We show that patients with neuromodulation improve to a greater extent than those without neuromodulation.

Funding

This study did not receive any funding or financial support.

Disclosures

The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. Dr Pilitsis is a consultant for Boston Scientific, Nevro, TerSera, and Abbott and receives grant support from Medtronic, Boston Scientific, Abbott, Nevro, TerSera, NIH 2R01CA166379-06, and NIH U44NS115111. She is medical advisor for Aim Medical Robotics and Karuna and has stock equity. Dr Argoff is a consultant for Teva, Lilly, Allergan, Amgen, Novartis, and Flowonix. He provides research support to Teva and Allergan. He has stock in Pfizer. He is part of the Speaker's Bureau for Theranica, Tercera, Teva, Lilly, Allergan, Amgen, Novartis, and Flowonix.

COMMENT

This study describes a single center experience in the comprehensive, multidisciplinary treatment of chronic pelvic pain. This is a particularly difficult pain problem, even for dedicated pain specialists. Patients with chronic pelvic pain not only suffer from their debilitating pain, but they must also navigate through a confusing medical system populated by multiple different subspecialists with expertise in the various organ systems present within the pelvis (GU, OB, GI, etc), very few of whom are actually dedicated to the diagnosis and treatment of pelvic pain syndromes. Further, many of the interventional pain procedures for pain from spinal origin, such as epidural injections and spinal cord stimulation, are often ineffective when treating pelvic pain syndromes. In the end, both patients and physicians are routinely frustrated during the treatment of chronic pelvic pain.

This study illustrates the importance of the multidisciplinary format for the effective management of chronic pelvic pain. A quick glance at the diverse treatment options, which span so many disciplines, indicates that the solo practitioner would be poorly equipped to manage these pain conditions.

An important take home message here for the neurosurgeon is that functional neurosurgery plays an important role in the effective treatment of these patients, especially for those with predominantly neuropathic pain. Neurosurgeons need not recoil in horror at the thought of treating patients with chronic pelvic pain. Instead, functional neurosurgeons working within the context of a comprehensive, multidisciplinary pelvic pain center can play a crucial role in the treatment of these patients.

Christopher J. Winfree

New York, New York