Note:  Dr. Joanna Zakrzewska at the Pain Management Centre, National Hospital for Neurology and Neurosurgery in London, UK is the International Research Coordinator for the Facial Pain Research Foundation.

She is also a member of the FPRF International Consortium of Scientists.  The FPRF assisted in the funding of the research article printed last month in the Journal of Headache and Pain.  The results of the study clearly indicate that present treatments for TN don’t work well for sufferers….”there remains an unmet need for additional treatment options.

 

RESEARCH ARTICLE                           Open Access

Burden of illness of trigeminal neuralgia

among patients managed in a specialist

center in England

Lasair O’Callaghan1* , Lysbeth Floden2, Lisa Vinikoor-Imler1, Tara Symonds3, Kathryn Giblin4, Chris Hartford2 and Joanna M. Zakrzewska5,6

Abstract

Background: Trigeminal neuralgia (TN) causes severe episodic, unilateral facial pain and is initially treated with antiepileptic medications. For patients not responding or intolerant to medications, surgery is an option.

Methods: In order to expand understanding of the pain-related burden of illness associated with TN, a cross-sectional survey was conducted of patients at a specialist center that utilizes a multidisciplinary care pathway. Participants provided information regarding their pain experience and treatment history, and completed several patient-reported outcome (PRO) measures.

Results: Of 129 respondents, 69/128 (54%; 1 missing) reported no pain in the past 4 weeks. However, 84 (65%) respondents were on medications, including 49 (38%) on monotherapy and 35 (27%) on polytherapy. A proportion of patients had discontinued at least one medication in the past, mostly due to lack of efficacy (n = 62, 48%) and side effects (n = 51, 40%). A total of 52 (40%) patients had undergone surgery, of whom 30 had microvascular decompression (MVD). Although surgery, especially MVD, provided satisfactory pain control in many patients, 29% of post-surgical patients reported complications, 19% had pain worsen or stay the same, 48% were still taking pain medications for TN, and 33% reported new and different facial pain.

Conclusions: In most PRO measures, respondents with current pain interference had poorer scores than those without pain interference. In the Patient Global Impression of Change, 79% expressed improvement since beginning of treatment at this clinic. These results indicate that while the multidisciplinary approach can substantially alleviate the impact of TN, there remains an unmet medical need for additional treatment options.

Keywords: Trigeminal neuralgia, Trigeminal nerve, Facial pain, Microvascular decompression, Multidisciplinary approach, Patient related outcomes

Background

Trigeminal neuralgia (TN) is a rare condition that affects the trigeminal nerve, resulting in extreme, sporadic, sudden, electric shock-like unilateral facial pain [1]. The attacks typically last only for a few seconds to a maximum of 2 min and can occur in quick succession with a frequency of 1–

* Correspondence: lasair.ocallaghan@biogen.com

1Biogen, 225 Binney St, Cambridge, MA 02142, USA

Full list of author information is available at the end of the article

50/day [2]. These episodes of TN, encompassing the dur­ation of recurrent attacks, can last for periods of days to even months, but can go into periods of remission which can last for months [3]. The condition occurs most frequently in people over 50 years of age, and is more prevalent in women than in men [4]. The intensity and unpredictability of the pain can be physically and mentally incapacitating, and result in a severe burden of illness (BOI) and impaired patient quality of life (QoL) [5, 6]. Further,

O’Callaghan et al. The Journal of Headache and Pain            (2020) 21:130 Page 2 of 10

diagnostic delays [7], suboptimal management strategies, complications from treatments, and resistance to treatment may contribute to the disease burden [6].

Recently, TN was classified into 3 categories: classical (primary), in which vascular compression of the nerve with morphological changes in the trigeminal root is observed; secondary, in which major neurologic disease such as mul­tiple sclerosis or tumor of the cerebellopontine angle has been identified; and idiopathic, in which no cause has been found [2, 8].

Primary treatment for TN has been pharmacological therapy, with the antiepileptic drugs (AEDs) carbamazepine and oxcarbazepine being first-line [8]; a range of other AEDs such as lamotrigine pregabalin, gabapentin, pheny-toin, and baclofen are utilized when first-line drugs are inef­fective or contraindicated [8]. However, large claims studies in the USA and smaller studies in Europe show frequent change of medication, suggesting poor efficacy and/or poor tolerability [9–11]. In addition, common side effects of these drugs in the TN population include significant cogni­tive impairment [12]. For patients non-responsive or in­tolerant to medications, surgery may be an option, with microvascular decompression (MVD) regarded as the most effective procedure [8]. Although neurosurgical procedures in selected TN patients can produce excellent results, it is not clear which patients will have good outcomes, as stud­ies that have examined factors contributing to surgical out­comes have been limited [8].

There is considerable evidence that TN has a significant impact on QoL [5, 10, 13]. The natural history of TN has generally been considered progressive, with few remission pe­riods and increasingly longer and more intense relapses grad­ually becoming less responsive to AEDs [14, 15]. However, recent studies suggest that patients managed in specialist cen­ters utilizing a multidisciplinary approach may experience dis­ease stabilization, and even improvement [5, 9, 10, 16, 17].

The current study is a cross-sectional component of a longitudinal survey project, and consists of assessments per­formed at a single timepoint, in a cohort of patients receiv­ing a high level of clinical care at a specialist facility which has been managing TN patients over several years using a multidisciplinary care pathway. The aim of this study was to gain increased insight into the BOI of TN by looking at medication use, surgery, pain experience and quality of life as measured by several PROs, and to determine whether current treatments are meeting patient needs. The well-documented and consistently recorded medical and thera­peutic history of these patients allowed a high level of speci­ficity and accuracy in the analysis of the results.

Methods

Patient recruitment

Patients were recruited for the study in 2018 from a dedi-

cated multidisciplinary facial pain clinic within a London

teaching hospital. At this facility, if patients are taking medication(s), reviews are every 6 months on average; pa­tients may be discharged if they are no longer taking med­ications following surgery. This single-site patient population has been managed longitudinally since 2007 in a specialized multidisciplinary team model, with access to physicians, dentists, clinical psychologists, a clinical nurse specialist, a neurologist and 3 neurosurgeons. The multi­disciplinary team follows the hospital-approved guidelines, which are based on published guidelines for TN [18]. Pa­tients at the facility are clinically contacted a minimum of twice yearly, either face to face, or by telephone by a clin­ical nurse specialist [17].

Patients were initially contacted and informed of the study by a member of the multidisciplinary team. Patients who were able to be contacted and were reported to have primary TN were invited to complete the survey. This was the first time they were being asked by the multidisciplin­ary facial pain clinic to complete a survey electronically.

Survey methodology

This cross-sectional survey was deployed using a web-based system. If patients were unwilling or unable to complete the online form, they were offered a paper ver­sion of the survey. The survey included items about pain interference, history and experience of medication use, history and experience of surgery related to TN, and 5 PRO measures. The 5 PRO measures were: 1) The Penn-Facial Pain Scale-Revised (PENN-FPS-R), an instrument to assess patient-reported impact of facial pain, was used to inform pain status and the interference of facial pain with patients’ activities of daily living (ADLs) during the past week, including general activity, walking, work, mood, enjoyment of life, relations with others, and sleep [19]; 2) The Patient Global Impression of Change (PGIC) [20] was used to evaluate patients’ perception of change in health compared to start of treatment; 3) The EQ-5D-5L (Euro-Qol-5 Dimension-5 Level) was used to evaluate health utility using the UK value set and the EQ-VAS (EuroQol Visual Analog Scale) of the EQ-5D-5L was used to evalu­ate global health status on the day of the survey; 4) the Brief Pain Inventory – Short Form (BPI-SF) was used to assess level of pain and general pain interference in the last 24 h [21]; 5) Depression and anxiety over the last week was assessed with the Hospital Anxiety and Depression Scale (HADS) [22].

Data analysis

Descriptive analyses were used to report demographic and health information, patient-reported pain experience, treatment history and PRO instrument scores. Stratifica­tions were made based on pain status, current medication use (monotherapy/polytherapy/no current meds), and sur­gery. For the surgical stratification, patients were classified

O’Callaghan et al. The Journal of Headache and Pain              (2020) 21:130   Page 3 of 10

as (1) “microvascular decompression (MVD) only” if hav­ing one or more MVD procedures but no non-MVD pro­cedures for TN; (2) “Ablative surgery” if having one or more ablative procedures such as gamma knife, radiofre-quency thermocoagulation, including stereotactic radio-surgery, but no MVD procedures; (3) “MVD + ablative surgery” if having procedures of both types, or (4) no sur­gery. Quantitative analyses were performed using SAS software (SAS Institute, Cary, USA).

Results

Study participants and demographics

A cohort of 235 patients were initially screened for the study, of whom 195 (female 124; male 70; 1 missing) were invited to participate. Of them, 21 declined, and 174 pa­tients (female 111; male 63) initially agreed to participate. Patients could either complete an online survey or, if they requested, were sent a paper survey. Ultimately, a total of 129 patients completed and returned usable patient sur­veys, which formed the basis of the analyses (Fig. 1).

Participants had been treated at this clinic for an aver­age of over 6 years, and had an average of over 12 years since their first recorded attack.

Of the respondents, the majority were female (65%), White (88%), married (71%), ≥ 65 years (60%) and retired (56%) (Table 1). The age of respondents ranged from 39 to 85 years; the mean age was 65.7 years; median age was 67 years. Demographic characteristics are reported overall, by current pain experience, current medication use, and surgical history. There were no substantial differences between respondents and non-respondents with regards to mean age; however, among invitees, a higher percent­age of those over 55 years old responded compared to younger patients. The response rate for invitees was 66%

(129/195); for those who received the survey, the partici­pation rate was 74% (129/174); 64% (111/174) were fe­male, and of this population 76% (84/111) responded. Overall, 68% (84/124) of female invitees and 64% (45/70) of male invitees participated. The male response rate among survey recipients was 71% (45/63).

Pain prevalence

Among respondents, over half (69/128; 54%) reported that they had not experienced pain in the past 4 weeks. How­ever, only 50 patients scored a zero on the Penn-FPS-R measure, indicating no pain interference. Of the 69 who reported not experiencing pain in the past 4 weeks, 37 (54%) patients were currently not on any medication and 38 (55%) had undergone 1 or more surgical procedures (Table 2). Of those who reported pain episodes in the previous 4 weeks, the most common triggers were movement of the mouth (including talking) (35%), and ADLs (including face touching) (33%), however, just over a quarter (26%) of respondents reported spontan­eous occurrence of pain.

Treatment history

Medications

All patients had taken medication for their TN pain; the most common medications taken by patients were carba-mazepine and oxcarbazepine (Table 3). Other AEDs such as lamotrigine, pregabalin, and gabapentin were the next most frequently used. While some patients reported taking opioids or non-steroidal anti-inflammatory drugs during the course of their disease, these medications were not prescribed at the specialist center.

Over the course of treatment, patients had taken a mean of 3.7 medications with a range of 1–13 (Table 4).

Fig. 1 Survey Response Results

O’Callaghan et al. The Journal of Headache and Pain             (2020) 21:130 Page 4 of 10

Table 1 TN Patient Demographics Stratified by Pain, Medication Use, and Surgical Historya

Total Sample Pain Medication Surgery
Any attacks in past 4 weeks No attacks in past 4 weeks Current monotherapy Current         No current

poly therapy therapy

No surgery MVD only Ablative surgery MVD +
ablative
surgery
Total N                                       129 Age, Continuous (years,%) 59 69 49 35 45 77 30 13 8
Mean (SD) 65.7 (12) 66.2 (11) 65.1 (12) 69.3 (11) 64.8 (11) 62.6 (11) 67.4 (11) 61.5 (11) 69.1 (13) 60.9 (8)
Median (IQR) 67.0 (59, 68.0 67.0 71.0 66.0 64.0 69.0 63.0 71.0 63.5
73) (58, 74) (60, 72) (62, 79) (55, 74) (57, 71) (61, 74) (51, 71) (65, 82) (53.5,
67)
Min/Max 39/85 39/85 41/85 39/85 47/85 41/79 39/85 42/79 44/84 49/70
Age, Categories (n, %)
35–44 6 (5) 2 (3) 4 (6) 2 (4) 0 4 (8.9) 4 (5.2) 1      (3) 1    (8) 0
45–54 17 (13) 7 (12) 10 (15) 2 (4) 8 (23) 7 (16) 5 (7) 9 (30) 1    (8) 2 (25)
55–64 29 (23) 15 (25) 14 (20) 11 (22) 6 (17) 12 (27) 18 (23) 7 (23) 1    (8) 2 (25)
65+ 77 (60) 35 (59) 41 (59) 34 (69) 21 (60) 22 (49) 50 (65) 13 (43) 10 (77) 4 (50)
Gender, n (%)
Female 84 (65) 37 (63) 46 (67) 32 (65) 20 (57) 32 (71) 54 (70) 19 (63) 7 (54) 4 (50)
Male 45 (35) 22 (37) 23 (33) 17 (35) 15 (43) 13 (29) 23 (30) 11 (37) 6 (46) 4 (50)
Race, n (%)
White
113 (88) 51 (86) 61 (88) 42 (86) 30 (86) 41 (91) 66 (86) 27 (90) 12 (92) 7 (88)
Asian/Asian British 8 (6) 3 (5) 5 (7) 5 (10) 1      (3) 2 (4) 7 (9) 1      (3) 0 0
Black/African/ 7 (5) 5 (9) 2 (3) 1    (2) 4 (11) 2 (4) 4 (5) 2 (7) 0 1    (13)
Caribbean/Black
British
Other 1    (1) 0 1      (1) 1    (2) 0 0 0 0 1    (8) 0

aMissing n = 1 in some pain report and some surgery statistics MVD Microvascular decompression

Current mean medication use per patient was 1.1 medi­cations, with some patients currently taking up to 5 medications. At the time of survey completion, 84/129 (65%) patients were on medication, with 49 (38%) on monotherapy and 35 (27%) on polytherapy of 2 or more medications; 45/129 (35%) were using no medications.

Surgery

A total of 52/129 (40%) patients had undergone a surgical procedure to manage their TN. The median time since last surgery, based on 21 participants for whom these data were available, was about 3 years. The most common sur­gery was MVD (38/52; 73%) with 8 of these patients also having another type of surgery (Table 6). MVD was also the most recent surgery for most patients (33/52).

Table 2 Pain Experience and Medication/Surgery – N(%)

Overall patients had a positive post-surgical experi­ence, with 36/52 (69%) of all patients who had sur­gery reporting much better pain relief including 21/52 (40%) reporting complete pain relief (Table 7). Of those who had MVD only, 17/30 (57%) reported 100% pain relief and 22/30 (73%) felt much better. However, among all patients who underwent surgery 7/52 (13%) patients felt no relief. Ten of the 52 (19%) had worsening of pain or no change in pain post-surgery. However, none of the patients reported hav­ing much worse pain after surgery and of those who had surgery, 41 (79%) stated surgery was better than staying on pain medications. When patients were asked about their most recent surgery, 15/52 (29%) of respondents reported complications, the most com­mon of which were cerebrospinal fluid leak, unsteady on

Pain Experience in Past 4 Weeksa Taking Medication Not Taking Medication Had Surgery No Surgery
None (N = 69)
Yes (n = 59)
32 (46%)

51 (86%)

37 (54%)

8 (14%)

37 (54%)

14 (24%)

31 (45%)

45 (76%)

a1 participant had missing data for surgery

O’Callaghan et al. The Journal of Headache and Pain              (2020) 21:130 Page 5 of 10

Table 3 History of Specific Medication Use for TN, n (%)

Medication, (N = 129) Never
took
Currently taking Took but stopped within last 6 months Took but stopped more than 6 months ago
Carbamazepine 18 (14) 30 (23) 5 (4) 76 (59)
Oxcarbazepinea 43 (34) 39 (31) 9 (7) 37 (29)
Gabapentina 71 (56) 8 (6) 0 49 (38)
Pregabalina 92 (72) 11  (9) 2 (2) 23 (18)
Phenytoina 119 (93) 2 (2) 1 (1) 6 (5)
Amitriptylinea 97 (76) 1  (1) 1 (1) 29 (23)
Nortriptylinea 119 (93) 1  (1) 1 (1) 7 (6)
Drug patches or lidocaine cream, spraya 111     (87) 3 (2) 2 (2) 12 (9)
Opioids, eg, morphine, fentanyl patchesa 116 (91) 2 (2) 1 (1) 9 (7)
Tramadola 114 (89) 2 (2) 2 (2) 10 (8)
NSAIDs for TNb 86 (68) 7 (6) 3 (2) 31 (24)
Lamotriginea 94 (73) 21 (16) 6 (5) 7 (6)
Duloxetinea 124 (97) 2 (2) 0 2 (2)
Botulinum Toxina 127 (99) 1  (1) 0 0
aMissing n = 1; bMissing n = 2

NSAIDs non-steroidal anti-inflammatory drugs; TN trigeminal neuralgia

feet, and headache; other complications reported were ringing in the ears, dizziness, and facial weakness.

Pain medications for TN were being taken by 25/52 (48%) who had undergone surgery (Table 6), and 17/ 52 (33%) reported new and different facial pain. Of the 17 patients with new and different facial pain, almost half reported recurring pain within 2 months or less of surgery (n = 8). Even with MVD, 5/38 (13%) required repeat MVD surgery, and all 5 of these patients still had some interference in ADLs as assessed by the Penn-FPS-R.

6-month pain experience

Of 53 respondents who reported pain in the past 6 months, 7 (13%) felt daily pain while 14 (26%) had pain-free periods for months. A total of 39 of these 53 partici­pants had pain in the past 4 weeks (Table 6).

Disease impact: PRO measures

Those with current pain interference as assessed by the PENN-FPS-R (77/127, 61%) showed numerically lower (ie, worse) quality of life scores than those reporting no pain interference on the EQ-5D-5L index (0.80, SD = 0.214 ver­sus 0.96, SD = 0.141, respectively). The EQ-VAS showed similar results: those with current pain interference had lower global health scores (65.9, SD = 25.46) than those who did not (82.9, SD = 21.39). Patients who were not on medication and those who had undergone an MVD had numerically better overall outcomes on the PGIC and BPI measures than those who were on medication and those who did not have MVD. Patients with no current pain interference scores also reported numerically better scores on the BPI-SF pain interference scale (2.10, SD = 2.436 versus 0.18, SD = 0. 628). In the PGIC measure, which asked participants if they experienced improvement since starting treatment at this clinic, 79% expressed their

Table 4 Historical Medication Use for TN

Current Medication Use

Total                                   Monotherapy                                            Polytherapy*                                            No Current Medication

(N = 129)                            (N = 49)                                            (N = 35)                                            (N = 45)

Number of Medications Taken for TN Ever

Mean (SD) 3.7 (2.2) 3.0 (1.7) 4.8 (2.5) 3.5 (2.10)
Median (IQR) 3.0 (2, 5) 3.0 (2, 4) 5.0 (3, 6) 3.0 (2, 4)
Min-Max 1–13 1–8 2–13 1–12

Nearly half of respondents (62/129; 48%) had at some point discontinued a medication due to lack of efficacy and 51/129 (40%) had discontinued due to side effects (Table 5)

OCallaghan et al. The Journal of Headache and Pain           (2020) 21:130 Page 6 of 10

Table 5 Reasons for Medication Discontinuationa

Number of Patients, n (%)
Total Patients (N) 129
Not relieving pain 62 (48)
Changed to a different drug 59 (46)
Difficult side effects 51 (40)
No longer needed (remission) 28 (22)
No longer needed (surgery) 28 (22)
Other reason 21 (16)
aPatients could select more than one reason

condition had very much or much improved with 10 (8%) reporting worsening of their condition. The HADS anxiety and depression scores, on average, were within the normal range (0 to 7) for both those who had experienced pain episodes in the past 4 weeks and those who had not.

A summary of PRO measure results by TN attack fre­quency is shown in Table 8. A summary of PRO meas­ure results for medication and surgical history is included in Supplement 1, Trigeminal Neuralgia PRO Scores Medication and Surgery History.

Discussion

This cross-sectional study, conducted at a specialist facial pain treatment facility, consisted of a subpopulation of pa­tients of an earlier study [6]. The study yielded several key findings. Overall, the results indicate that a multidisciplinary

Table 6 Pain Control by Pain, Medication and Surgical History

care pathway can produce substantial benefit in a majority of patients, as evidenced by 79% of patients reporting improve­ment in the PGIC measure since beginning of treatment at this clinic. In addition, the average HADS score at the time of survey was within the normal range; this is encouraging in view of the fact that a prior study of 225 patients at this cen­ter (that included all 129 respondents of this study) was con­ducted at an earlier timepoint, and showed 36% had mild to severe depression and over 50% had anxiety as found on HADS [6]. This apparent reduction in anxiety and depres­sion over time for the survey population is notable, given that a recent epidemiological study showed a rise in anxiety, de­pression and poor sleep after a diagnosis of TN [23].

Even though most patients reported improvement since beginning treatment, the majority were still on medications, with 42% of those individuals on polytherapy. At the time of the survey patients were taking an average of 1.1 medica­tions, however overall treatment history shows patients on average had taken 3.7 drugs for TN, and as many as 13 dif­ferent drugs. During the course of treatment a substantial percentage of patients had discontinued 1 or more medica-tion(s) for various reasons, frequently due to lack of efficacy or tolerability. While polytherapy can yield clinical benefits, it also carries increased risk of AEs and drug interactions [24–26]. A study by Di Stefano et al. [9] found that carba-mazepine and oxcarbazepine, the 2 medications commonly recommended as first-line therapy for TN, produce side ef­fects that can lead to treatment withdrawal. In addition,

129

Currently Taking Medicationa 84 (65) 51 (40)                             32 (25)       49 (38)

Not currently taking                         45 (35) 8 (6)                         37 (29)       0

medication to manage pain

Frequency Pattern of Pain experienced in past 6 monthsc; n (%)

N n = 53 n = 39 n = 14 n = 24
Daily 7 (13) 6 (15) 1 (7) 4 (17)
For days, then I have days or weeks free of TN 17 (32) 10 (26) 7 (50) 5 (21)
For weeks, then I have days or weeks free of TN 4 (8) 4 (10) 0 3 (13)
I have months completely free of TN 14 (26) 10 (26) 4 (29) 7 (29)
I have months free of TN attacks but with a dull ache in the background 11      (21) 9 (23) 2 (14) 5 (21)

a1 missing

b1 patient had peripheral cryotherapy before attending specialist center

cOf patients who reported pain experience in past 6 months