Medicine · 7 authors, 2 centres
This summary was generated by AI from a single paper. It has not been reviewed by a clinician and is not clinical advice. Verify against the source before acting on it.
This case report describes a 41-year-old man with concurrent facial-onset sensory and motor neuronopathy (FOSMN) and myasthenia gravis (MG), a rare co-occurrence. The patient presented with progressive facial numbness, eyelid closure difficulty, slurred speech, and dysphagia, and tested positive for anti-AchR and anti-Titin antibodies. Treatment with pyridostigmine and prednisolone improved symptoms, suggesting a possible immune-mediated link between the two conditions.
**Background:** Facial-onset sensory and motor neuronopathy (FOSMN) is an extremely rare disorder, with only about 100 cases reported to date. Its pathogenesis is not fully understood, with hypotheses ranging from neurodegeneration to autoimmunity. Myasthenia gravis (MG) is a well-characterized autoimmune disorder affecting the postsynaptic neuromuscular junction, mediated by antibodies such as anti-AchR and anti-Titin. The coexistence of FOSMN and MG has rarely been reported, and this case aims to explore a potential association.
**Methods:** This is a single case report of a 41-year-old male admitted to the hospital with a 6-year history of progressive right-side facial numbness and incomplete right eyelid closure, followed by slurred speech for 3 years and dysphagia for 1 month. The patient underwent comprehensive neurological examination, laboratory tests (including MG-related antibodies), neostigmine test, chest computed tomography, head magnetic resonance imaging, low-frequency repetitive electrical stimulation test, electromyography, nerve conduction studies, and evoked potential studies. Treatment included pyridostigmine bromide 60 mg 1-3 times daily and prednisolone 60 mg daily with gradual taper, along with supportive therapies.
**Key Results:** The patient's serum was positive for anti-AchR antibody at 7.17 nmol/L (reference <0.5 nmol/L) and anti-titin antibody at 1.55 nmol/L (reference <1 nmol/L). The neostigmine test was positive. Low-frequency repetitive electrical stimulation showed a decreasing trend in compound muscle motor potential amplitude. Nerve conduction studies revealed slowed motor nerve conduction velocities in the right facial nerve (temporal branch) and left facial nerve (marginal mandibular branch), and slowed sensory nerve conduction velocities in the right sural nerve and right ulnar nerve. Blink reflexes showed delayed R1, R2, and R2' responses. Electromyography showed no spontaneous power generation. Head MRI was normal. After treatment, the patient noticed improvement in dysphagia, dyspnea, and facial dysesthesia, lasting at least 4 months, but no further progress was observed over 20 months.
**Clinical Implications:** This case highlights the rare coexistence of FOSMN and MG, suggesting that FOSMN may have an immune-mediated component in some patients. The positive response to pyridostigmine and prednisolone supports this hypothesis. The presence of anti-AchR and anti-Titin antibodies in a FOSMN patient expands the spectrum of FOSMN and underscores the need for further research into immunological mechanisms. Clinicians should consider MG in FOSMN patients presenting with fluctuating symptoms and positive antibody tests.