Pain is diagnosed in 29-86% of patients with multiple sclerosis (MS) and can appear at any time of the disease. Pain in MS is directly related to indicators of functional limitation, disability and a decrease in the quality of life of patients. Central neuropathic pain (NP), which is represented by neuropathic dysesthetic pain (NDP), Lhermitte phenomenon (FL) and trigeminal neuralgia (TN), is of particular importance among the pain phenomena in patients with MS.
Patients with MS are a group with an increased risk of NP, precisely due to the increased frequency of central NP in them. In patients with MS, compared to PZO, the probability of detecting NDP of central origin is increased by 11.01 times (1.49-81.42; p = 0.02). In patients with MS, central NP is presented in the form of central NDP - 11.8% (8.8%-15.8%), FL - 4.1% (2.4%-6.8%) and TN - 0, 6% (0.2%-2.2%). In patients with MS, in two-thirds of cases, central NDP has an paroxysmal course (with a complete absence of pain sensations or with minor pain between attacks). Patients with MS describe central NDP using several descriptors at the same time (most often - "burning", "freezing", "tingling"). NDP in patients with MS in most cases covers several areas of the body (on average - 2.5 areas of the body) and is most often localized in the lower extremities. FL by patients with MS is described by only one descriptor (in the vast majority of cases as "throw"), as a rule, it covers 2 or 3 conditional areas of the body and is most often localized in the back and neck area.
Among patients with MS, the increased risk of central NDP is associated with female gender, the presence of subclinical depressive and anxiety disorders according to the HADS scale, longer disease duration, with a progressive type of MS, and with the degree of disability according to the EDSS scale. Factors independently associated with central NDP were subclinical anxiety disorders according to the HADS scale (odds ratio (OR) = 2.90, 1.08-7.74; p = 0.03) and progressive type of MS (OR = 3.25 , 1.11-9.46; p=0.03). In patients with comorbid non-NP, the probability of diagnosing a central NDP is significantly higher than a peripheral NDP (OR = 5.54, 1.60-19.13; p = 0.01).
During the two-year observation period, in patients with MS, the frequency of NDB is 15.6% (11.4%-21.0%), FL - 5.1% (2.8%-8.8%), TN - 0 .9% (0.3%-3.3%), and they are significantly lower than the rate of occurrence of non-NP - 33.9% (28.0%-40.5%). During the two-year observation period, in patients with MS, the frequency of relapse of NDP is 8.8% (3.0%-23.0%) and is significantly lower than the recurrence rate of non-NP - 64.9% (53.5%-74 .8%). NDP, which arose (recurred) in patients with MS, in almost two-thirds of cases becomes chronic (lasts more than 3 months). NDP, at the time of its occurrence (recurrence), is mainly localized in the lower back and lower limbs, occupies , on average, 2 parts of the body, is most often characterized as "periodic pain with pain-free periods" and is most often described by patients in terms of: "burning ", "freezing", "tingling". The chronicity of NDP, compared to its initial indicators, is accompanied by an expansion of the zone of pain sensations, an increase in the frequency of individual clinical patterns of NDP in the form of constant pain, and a significant decrease in the intensity of NDP according to the VAS (4.0 (3.0-5.0) points at the initial observation and 3.0 (2.0-4.0) points after 3 months). Painful sensations at the debut of FL in the vast majority of cases are localized in the back and neck with coverage of 2 or more areas of the body and are most often characterized by patients as "shooting".
During the two-year observation period, predictors of the development of NDP were the progressive type of MS (relative risk (RR)=2.90; 1.47-5.71; p<0.01) and an increase in the EDSS scale indicators for every 0.5 points (RR=1, 12; 1.01-1.24; p=0.03). An independent predictor of the occurrence of NDP was the progressive type of MS (OR=2.60; 1.30-5.18; p=0.01). Predictors of the chronicity of the resulting NDP were subclinical anxiety disorders according to the HADS scale (OR=1.61-34.95; p=0.01) and subclinical depressive disorders according to the HADS scale (OR=11.14; 1.92-64 .54; p=0.01). In the multivariate analysis, only subclinical depressive disorders according to the HADS scale acted as an independent predictor of NDP chronicity (OR=7.14; 1.12-45.59; p=0.04). During the two-year observation period, a short period of MS was a predictor of the occurrence of FL: an increase in the duration of MS in patients for each subsequent year was associated with a significant decrease in the RR of the occurrence of FL by 1.15 (1.02-1.29, p=0.02) times.
