Visual impairment, sensory disturbances, weakness and fatigue are among the most commons symptoms in MS, but there are others such as pain, which is highly distressing and can easily affect day-to-day life. This symptom is often difficult to describe by patients and is sometimes difficult to diagnose and treat by clinicians.
Let’s start with the fact that pain can be very heterogeneous, not only from patient to patient but also in the same patient from time to time. In classifying pain associated with MS, it is important to consider not only its characteristics but also its underlying mechanisms: Pain directly caused by MS lesions vs. pain caused by other MS-related phenomena, such as spasticity and loss of mobility. O’Connor et al. have proposed a practical classification system for pain conditions associated with MS:
Such heterogeneity may partially explain the wide variation in the reported prevalence of MS-related pain: 40 – 86%. So yes, MS hurts! But the most worrisome thing is that, according to some reports, up to 50%of MSers with pain go untreated. Perhaps one of the main reasons for this is the difficulty in recognizing and measuring pain. But how do we objectively measure something that is inherently subjective? To this end, several tools have been proposed in the literature and among them, those aiming to identify and distinguish neuropathic (due to nerve damage) and nociceptive (due to damage to other body tissues) pain are particularly helpful.
To date, only a few studies investigating pain in pwMS have used a combined approach based on physical examination and validated questionnaires. The study below, using highly specific diagnostic criteria for identifying the different types of pain in MSers, showed that the following factors are associated with a higher probability of having pain:
- Female gender
- Higher EDSS score
- Older age
- Longer disease duration
When addressing pain related issues, we all need to tell more, ask more and listen better! Let us know what you think!
Solaro C, Cella M, Signori A, et al. Identifying neuropathic pain in patients with multiple sclerosis: a cross-sectional multicenter study using highly specific criteria. J Neurol. 2018;265(4):828-835.
BACKGROUND: Pain is a common and heterogeneous complication of multiple sclerosis (MS). In this multicenter, cross sectional study, we aimed at investigating the prevalence of pain in MS using highly specific criteria for distinguishing the different types of pain.
METHODS: After a structured interview, in patients with pain, clinical examination and DN4 questionnaire were used for distinguishing neuropathic and nociceptive pain. In subjects with neuropathic pain, the Neuropathic Pain Symptom Inventory was used for differentiating neuropathic pain symptoms.
RESULTS: We enrolled 1249 participants (832 F, 417 M, mean age 33.9 years, mean disease duration 8 years, mean EDSS 3.2); based on clinical evaluation and DN4 score 429 patients (34.34%) were classified with pain (470 pain syndromes): 286 nociceptive pain syndromes and 184 neuropathic pain syndromes. Multivariate analysis showed that pain was associated with age, gender and disease severity and that neuropathic pain was distinctly associated with EDSS.
CONCLUSIONS: Our study, providing definite information on the prevalence, characteristics and variables associated with neuropathic pain due to MS, shows that a more severe disease course is associated with a higher risk of neuropathic pain. Our findings might, therefore, provide a basis for improving the clinical management of this common MS complication.
by Saúl Reyes