Small-Fiber Neuropathy

Small fiber neuropathy (SFN) is a condition in which the smallest nerve fibers are damaged. This leads to severe pain and disturbances in the body's automatic functions. As a result, quality of life is often substantially reduced. Pain is one of the main symptoms of small fiber neuropathy. Unfortunately, the effects of currently available pain medications are often disappointing and may be accompanied by unacceptable side effects. Although the smallest nerve fibers do not function properly in SFN, the brain also appears to play a role in the symptoms. Specialized brain imaging studies have shown that brain activity and certain neural connections differ between patients with SFN and healthy individuals. Therefore, the brain may also represent a suitable target for treatment. In several chronic pain conditions, it has been demonstrated that stimulation of specific brain regions using magnetic pulses delivered through a specialized coil can reduce pain. This treatment can be administered using repetitive Transcranial Magnetic Stimulation (rTMS), a safe and non-invasive technique that is already available in the Netherlands for people with severe depression. The effectiveness of rTMS has never been investigated in patients with small fiber neuropathy. In addition, the pain-relieving effects of treatment are often temporary. Maintenance treatment may offer a potential solution to this problem.

BACKGROUND Sjögren's syndrome is an autoimmune disease whose prevalence is estimated between 200 and 500 patients per 100,000 persons in France (120 to 500,000 patients). It affects women (90%) between 40 and 60 years of age and main manifestations are generalized sicca syndrome (ocular, oral, cutaneous) and arthralgia. In 20% of cases, Sjögren's syndrome is associated with peripheral neuropathies, and the most common form is painful small fiber neuropathy (SFN). SFNs are mainly featured by neuropathic pain including burns (90%), numbness (87.5%), tingling (72.5%), electric shocks (70%) and tingling (82.5%) and also autonomic disorders (50 to 70%). However, there are still important issues that deserve to be investigated by clinical and basic research. Among these issues, this study will focus on: * The impact of SFN on the quality of life of patients with Sjögren's syndrome. * The medico-economic impact of the SFN taking into account the repercussions on the quality of life, including professional life, usual care cost (analgesics, medical and paramedical consultations, hospitalizations or emergency). EXPECTED RESULTS * Confirmation of the major impairment in the quality of life of patients with Sjogren-associated SFN * Analysis of correlations to highlight or not clinical or biological factors associated with quality of life impairment. * Evaluation of the cost attributed to the presence of an SFN in patients with Sjögren's syndrome and the pharmaco-economic interest of conventional therapeutic management (analgesic treatment, consultation pain) compared to the cost of more aggressive immunomodulatory treatments.

This study will enroll patients with small fiber neuropathy (SFN). The study will look at an intravenous immunoglobulin (IVIG) called Panzyga. Panzyga is approved by the FDA as a therapy for Primary humoral immunodeficiency (PI) in patients 2 years of age and older; Chronic immune thrombocytopenia (ITP) in adults and Chronic inflammatory demyelinating polyneuropathy (CIDP) in adults. It has not been approved by the FDA for use in SFN. There is mounting evidence that Intravenous Immunoglobulin (IVIG) can cause pain reduction and improve objective nerve fiber densities on skin biopsies in great numbers in SFN patients. The primary outcome is quantified improvement in intraepidermal nerve fiber density (IENFD) on repeat skin punch biopsy after 6 months of IVIG treatment.

Small fiber neuropathy affects millions of peoples worldwide. The neuropathy is causing disabling burning pain and dysautonomia such as dizziness with standing, brain fog, fatigue, constipation, too much or too little sweating. The detection of nerve damage is complicated and not widely available; it requires either skin biopsy or specialized equipment and training. This project utilizes the mathematical processing of skin pictures for the purpose to extract the statistical features related to loss of small fibers. This approach can improve the availability of diagnosis of small fiber neuropathy.

We examine patients with different autonomic neuropathies and Ehlers Danlos syndromes compared to healthy controls at three different points over time (baseline, after 3 months and after 1.5 years) to gain knowledge about the course of this disease and understand its pathophysiology, with a focus on Small Fiber neuropathy. Moreover we will validate the german version of the Malmö POTS Score and establish an easy diagnostic scheme for patients in outpatient care.

The goal of this clinical trial is to assess effect of Intravenous immunoglobulins (antibodies) as compared to Placebo, on pain intensity in patients from 18-65 years with painful sensory neuropathy without a known cause. Effect of the treatment will be recorded by the patient in a digital diary.