Dados do Trabalho

Título

DOUBLE SERONEGATIVE OCULAR MYASTHENIA GRAVIS: A CASE REPORT

Apresentação do caso

Myasthenia Gravis (MG) is a chronic autoimmune neurological pathology acquired from the neuromuscular junction, characterized by weakness and fatigue of the skeletal muscles, which when restricted to ocular manifestations is called Ocular Myasthenia Gravis (OMG). Diagnosis occurs through the search for specific antibodies; however, the absence of AChR and MuSKA antibodies does not exclude the diagnosis in the presence of typical clinical features, and characterizes Seronegative Myasthenia Gravis, a condition that represents only 15% of MG cases. A 42-year-old female patient, hypertensive, diagnosed with hyperthyroidism for 8 years, using methimazole, searched a medical service due to severe headache in the frontal region, associated with ocular pain and right eyelid ptosis for 3 days. In the physical exam, she had isophotoreactive pupils, bilateral eye protrusion, absence of neurological deficits and preserved eye movements. Cranial tomography, magnetic resonance and angiotomography were performed, which ruled out intracranial lesions, tumors or vascular alterations. According to the evolution, the patient presented partial ptosis in the left eye, alternating with the right eye, which worsened at the end of the day. Due to the association with hyperthyroidism, therefore, an orbital resonance was requested, which did not document any abnormality. Nevertheless, specific antibodies, anti-AchR and anti-MuSK, were negative, as well as the electroneuromyography. The pyridostigmine test in graded doses was performed with partial improvement in ptosis, and prednisone 40mg/day was introduced, with significantly improved of the symptoms, making her asymptomatic.

Discussão

MG is a disease classically defined by the presence of specific autoantibodies; however, the description of seronegative cases, especially in OMG, has significant clinical relevance, since there is limited response to the use of anticholinesterase drugs for treatment. In addition, the case explores the differential diagnosis with Graves' ophthalmopathy, in which OMG is associated in approximately 5% of cases, and could justify the clinical picture of this patient.

Comentários finais

Thus, it is essential that in patients with challenging and unusual clinical conditions, there is a thorough investigation of the differential diagnoses and the disease subtypes. In this case, the clinical debate around the symptoms and the research for autoantibodies determined the final diagnosis of Double Seronegative Ocular Myasthenia Gravis.

Palavras-Chave

Ocular Myasthenia Gravis, Seronegative Myasthenia Gravis, Specific Antibodies anti-AchR and anti-MuSK