Central Sensitization in Vitamin D Deficiency
Condition: Vitamin D Deficiency; Central Sensitisation
MeSH terms: Vitamin D Deficiency
Study type: Interventional

Summary: 
      The purpose of this study is to investigate the presence of central sensitization in vitamin
      D deficiency and its effect on cutaneous silent period, pain, and quality of life. The
      secondary purpose of the study is to investigate whether a change in cutaneous silent period
      parameters, pain severity and neuropathic sensitization and quality of life after vitamin D
      replacement.
    

Detailed description: 
      Vitamin D deficiency is a pandemia. Main causes of this is insufficient exposure to sunlight.
      Vitamin D deficiency is related to conditions like various cancers, autoimmune diseases,
      hypertension and growth retardation in children (1).

      International Association for the study of pain has defined pain as "An unpleasant sensory
      and emotional experience associated with actual or potential tissue damage, or described in
      terms of such damage." (2). Pain lasting longer than 3 months has been deemed as chronic pain
      (3). Vitamin D deficiency influences various types of pain, including chronic pain (4,5,6,7).

      Vitamin D influences the musculoskeletal system via the calcium-phosphorus metabolism and the
      receptors found in skeletal muscle cells (8). Vitamin D deficiency has been shown to decrease
      muscle strength, the this decrease in proximal muscles affect postural stability and can
      increase falls. Vitamin D deficiency also causes problems in bone mineralization, causing
      isolated or widespread pain in muscles, bones and joints. These patients end up getting wrong
      diagnoses such as fibromyalgia, osteoarthritis, inflammatory arthritis, and chronic fatigue
      syndrome (1,7). Vitamin D deficiency causes hyperinnervation and hypersensitivity on nerves
      and cause pain to be felt more intensely (5).

      In a normal skeletal muscle, during an isometric contraction, a number of motor unit will be
      activated. These motor units produce a stable electromyography pattern and keep their own
      frequencies during contraction. If the nerve, tendon or a cutaneous nerve nearby is
      stimulated, electromyographic activity is disrupted and a bioelectric silence occurs. This is
      called cutaneous silent period (CSP). It is an inhibitory spinal reflex and its afferents
      consist of A-delta nerve fibers.

      In various studies, CSP has been shown to be clinically beneficial in conditions like
      peripheral neuropathy, syringomyelia, Parkinson's disease, restless leg syndrome and
      fibromyalgia.

      von Känel R et al. has investigated the effect of vitamin D deficiency on widespread pain
      index (WPI) and symptom severity score (SSS) and found out that it increases central
      sensitivity (8). In thei study, thy did not utilize any electrophysiologic objective
      measurements. Akyüz et al. have investigated the effect of vitamin D deficiency on chronic
      pain and nerve conduction studies; they have shown that vitamin D is correlated with various
      nerve conduction parameters while these parameters do not change after replacement (9,10).

      Patients with vitamin D deficiency and healthy controls with normal vitamin D levels will be
      compared in terms of cutaneous silent period parameters, pain severity and neuropathic
      sensitization and quality of life. Cutaneous silent period parameters (duration and latency
      ), The Leeds Assessment of Neuropathic Symptoms & Signs and Nottingham Health Profile will be
      used for the assessments. Patients with vitamin D deficiency will receive vitamin D
      supplementation therapy. Before and after therapy, cutaneous silent period parameters, LANSS
      scores and Nottingham Health Profile will measured before and 8 weeks after starting vitamin
      D supplementation therapy.
    

Intervention name(s): vitamin D
Intervention type(s): Dietary Supplement
Intervention description(s): Vitamin D replacement
Intervention MeSH terms: Vitamin D
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Screening
Keywords: Central Sensitisation; Cutaneous Silent Period; Vitamin D Deficiency