PAINDYS_Characterizing Pain in Fibrous Dysplasia of Bone/McCune-Albright Syndrome: an Exploratory Pilot Study

This scale allows the patient to rate the pain on a 100-mm horizontal line with a movable cursor. It ranges from 0 mm (0 cm), corresponding to "no pain," to 100 mm (10 cm), corresponding to "worst pain imaginable." Participants indicate, using the cursor, the point on the line that best represents their level of pain. The distance (in mm or cm) between 0 and the participant's mark determines the intensity of pain.

This self-assessment scale allows the patient to characterize the pain in terms of its intensity and its psychosocial repercussions by means of 11 scales rated from 0 (no pain or does not bother) to 10 (the most horrible pain you can imagine or completely bothers you).

The BPI also asks the patient to black out the painful areas on a diagram (front and back) and to put an "S" if the pain is on the surface or a "P" if it is deep. The questionnaire also asks the patient to indicate what treatment or medication he or she is taking for the pain and what percentage improvement has been obtained.

The measurements will be performed using an ATS thermode applied to the dominant arm of the patients. The Pathway-Medoc system associated with the thermode allows, from a base value of 32°C, to deliver adjustable temperature peaks (in the hot or in the cold and according to a regular slope of 1°C) and controlled by fast feedback, which allows to adapt to the different sensitivity thresholds of the C and A fibers. This device will be used to evaluate: the sensitivity threshold to heat, the sensitivity threshold to cold, the pain threshold to heat and the pain threshold to cold. The determination of each threshold will be established by an average of three measurements.

Mechanical pain thresholds and mechanical temporal summation will be assessed using standardized mechanical stimulation. Mechanical pain thresholds will be measured with calibrated PinPrick stimulators using a modified method of limits, with stimuli applied to the palm of the dominant hand (or non-dominant if necessary). Thresholds will be calculated as the geometric mean of ascending and descending series.

Mechanical temporal summation will be assessed using a 180 g Von Frey filament applied to the forearm. Pain intensity after a single stimulus and after a train of 10 stimuli at 1 Hz will be rated on a 0-10 visual analog scale. The temporal summation ratio will be calculated as the ratio between repeated and single stimulus pain ratings. Matched healthy volunteers will be tested at the same sites as patients.

Neuropathic Pain (DN4): This questionnaire estimates the probability of neuropathic pain in a patient, by means of four questions divided into ten items to be ticked. The practitioner or clinical research associate in charge of the study interviews or examines the patient and fills in the questionnaire himself. Each item is marked with a "yes" or "no" answer. Each "yes" is worth a score of 1, and each "no" is worth a score of 0. The sum of the scores gives the patient's score (out of 10); if the patient's score is equal to or greater than 4/10, the test is positive.

Neuropathic pain components will be assessed using the PainDETECT questionnaire. This self-administered questionnaire evaluates pain quality, temporal pattern, and radiation to estimate the likelihood of neuropathic pain. The total score allows classification of pain as unlikely, possible, or likely neuropathic

Small fiber neuropathy will be assessed using Sudoscan® (Impeto Medical, Paris, France), a rapid, non-invasive, and reproducible method for evaluating sudomotor function. The test measures electrochemical skin conductance of the hands and feet, reflecting sweat gland function and small fiber nerve integrity. Participants will be seated comfortably with palms and soles placed on stainless steel electrodes. A low-voltage current (4 V) will be applied for 2 minutes and 40 seconds. Electrochemical skin conductance values (µS) will be recorded for hands and feet, with lower conductance (<40 µS) indicating the presence of small fiber neuropathy and higher conductance (>60 µS) indicating normal function. Measurements will be performed twice, 30 minutes apart.

Dynamic mechanical allodynia will be assessed using a soft brush gently moved back and forth over the non-dominant forearm while the participant is seated comfortably in a quiet room. Pain intensity perceived during brushing will be rated on a 0-100 numerical rating scale.

Inflammatory pain will be assessed by the investigator during clinical examination according to current clinical criteria. The evaluation will be based on the presence of clinical signs suggestive of inflammation, including warmth, redness, swelling, edema, induration, and pain. The outcome will be reported as the presence or absence of inflammatory pain (Yes/No).

Signs of widespread pain will be assessed through clinical interview to calculate the Widespread Pain Index (WPI), commonly used in nociplastic pain conditions.

In addition, the presence of nociplastic pain will be determined based on an integrative assessment combining results from pain testing and clinical evaluation.

Clinical characteristics will be collected from the clinical examination and routine care investigations and will include a description of skeletal involvement and extra-skeletal manifestations.

he PSQI is a self-administered questionnaire with 19 items. It was developed to measure sleep quality in the month prior to the patient interview. This questionnaire includes 7 components: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, hypnotic medication use and daytime dysfunction.

The global score (0 to 21) is obtained by adding the sub-scores of the 7 components, each ranging from 0 to 3 points. In the absence of an answer to one or more questions, the subtotal using this question cannot be calculated and will affect the overall score.

The higher the overall score, the greater the impairment in sleep quality. An overall score >5 is an indicator of sleep disturbance.

It is a self-administered questionnaire completed by the patient and based on the Hamilton scale. The HAD scale is a tool for screening for anxiety and depressive disorders. It includes 14 items rated from 0 to 3. Seven questions relate to anxiety (total A) and seven others to the depressive dimension (total D), thus making it possible to obtain two scores (maximum score for each score = 21).

To screen for anxiety and depressive symptomatology, the following interpretation can be proposed for each of the scores (A and D): ≤ 7: normal case; 8 to 10: borderline case; ≥ 11: abnormal case.

The quality of life of patients is assessed by the general questionnaire 36-Item Short Form Survey (SF-36) which can be administered by self or hetero-questionnaire. The SF-36 questionnaire was developed from the Medical Outcome Study, a 149-item questionnaire that was developed to assess how the American healthcare system affects the outcome of care. The SF-36 questionnaire is composed of 36 items and makes it possible to assess the physical and mental health of an individual using eleven questions relating to eight aspects of health: Physical activity, limitations due to physical state, physical pain, perceived health, vitality, life and relationship with others, limitations due to the mental state and mental health. Scores between 0 and 100 are determined. Scores tending towards 100 indicate a better quality of life.

The PCS is a validated 13-item self-report questionnaire assessing catastrophic thoughts and feelings related to pain, including rumination, magnification, and helplessness. Items are rated from 0 to 4, with higher total scores indicating greater pain catastrophizing.

Evaluation of the CTX evolution after one year, defined as the difference [after - before], relative to the basal value (µg/L). For this purpose, a blood sample will be taken using 5 mL dry tubes.

The dosage of FGF23 (pg/mL) will be performed in order to evaluate bone remodeling. For this purpose, a blood sample will be taken using 6 mL EDTA tube.