ABSTRACT
Myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS) are antibody-mediated au- toimmune diseases of the neuromuscular junction. Previous works and recently published study on European LEMS registry demonstrate that Lambert- Eaton syndrome prognosis can be influenced by symptomatic drugs and survival by the treatment of overlying cancer or other autoimmune diseases when present. It is very important to early recognise this disease and to detect and treat efficiently associated comorbidities. Autoimmune myasthénia associated with anti- RAch and Anti-MUSK antibodies is associated with fluctuating weakness in ocular muscles and in muscles of the limb and trunk. Many first-line treatments for MG, including corticosteroids, acetylcholinesterase inhibitors, and non-steroidal immunosuppressive drugs, target inhibition of acetylcholine breakdown or T-cell function. Even though they allow MG patients to maintain an acceptable level of muscle strenght, functinal ability and quality of life, these treatments are non-specific and may be associated with important side effects. Moreover, MG patients may be or become refractary to these traitements during time or develop contreindication to the treatement do to coexisting comorbidities. Over the last few years, new biological agents against complement, the FcRn receptor, or B-cell antigens have been successfully tested in clinical trials. These new therapies with a relatively rapid mode of action and few side effects extend the possibilities for targeted immunotherapies and open new venues to better manage MG. Nevertheless, several challenges may occurs concerning the choice of the drugs in different situation, the frequancy of the administration and the potential long term side effects in the recent context of COVID-19 pandemic.
ABSTRACT
Background and aims: Small fiber neuropathy (SFN) is a polymorphous disease affecting thin nervous fibers conducting temperature and pain sensations and involved in autonomic transmission. Etiology is diverse and remains elusive in 70% of cases. Methods: We describe a case series of 6 patients who developed symptoms of SFN following SARS-COV-19 vaccination. Neurologic examination was normal whilst paraclinical results were consistent with SFN. Confirmation by skin biopsy was obtained in 4 cases. Results: Six patients, 5 female and 1 male, ages 31, 34, 39, 42, 44 and 62 years, consulted our department with intense pain and numbness involving the arms and legs 2 to 15 days following SARS-COV-19 vaccination. Neurologic examination was normal. A preliminary diagnostic protocol comprising autoimmune, metabolic, infectious and inflammatory panel, cerebral and spinal cord magnetic resonance imaging and electromyography was normal. Functional neurophysiologic testing showed reduced activation of fibers involved in sweat gland control indicating SFN. Skin biopsy of distal calf and thigh in 4 patients, three female and one male, showed rarefaction of thin intraepidermic nerve fibers in a non length dependent manner, allowing for a diagnosis of SFN. Conclusion: Whereas autoimmune, infectious, metabolic, toxic and genetic causes are well described in SFN, evidence of possible association with vaccination is confounding. Given their small caliber and richness of surface antigens, small nervous fibers are vulnerable to a wide spectrum of disease. Immunologic factors intervening on a predisposing substrate could be a hypothesis for the mechanism involved in development of SFN following SARS-COV-19 and possibly other vaccination.