Hypertrophic dural meningitis Hypertrophic dural meningitis is a rare group of diseases in which abnormal hypertrophy of the dura is the characteristic pathological change and clinical symptoms are headache, cranial nerve palsy, ataxia, and epilepsy. Hypertrophic dural meningitis is divided into two categories: idiopathic hypertrophic dural meningitis and secondary hypertrophic dural meningitis. The former is an exclusive diagnosis because no clear cause is found by comprehensive examination; the latter is a secondary change caused by other diseases, including infectious diseases, autoimmune diseases, nodular diseases, tumors, etc. The pathogenesis of idiopathic hypertrophic dural meningitis is still unclear, and it is generally believed that the disease is a specific class of autoimmune diseases. According to foreign literature, idiopathic hypertrophic dural meningitis is more frequent in men over 60 years of age, while our study found that it is more frequent in women aged 40-60 years in China, which may be related to different genetic background, survival environment, and of course, selective bias due to small observation sample size. Idiopathic hypertrophic dural meningitis presents with three main types of symptoms: headache, cranial nerve palsy, and symptoms due to venous sinus narrowing or occlusion. Our study found that more than 92% of patients with idiopathic hypertrophic duralgia presented to neurology with “headache” as the first complaint, and a minority of patients presented to ophthalmology with “loss of vision”. Most patients have a recurrent-remitting headache with no specific location or characteristics of pain. CT and MRI scans of the head often show no characteristic changes and are easily misdiagnosed as “primary headache”, most often as “tension-type headache”. Cranial nerve palsy is the second common symptom, in which the optic nerve is most frequently involved. The damage to the optic nerve may be related to local hypertrophic dural compression, inflammation and secondary ischemic changes. Some patients show manifestations of focal neurological impairment, such as hemiparesis and hemianesthesia, which are associated with local neurological impairment due to venous infarction caused by venous sinus stenosis or occlusion. Patients with suspected idiopathic hypertrophic dural meningitis must undergo enhanced MRI, which shows diffuse intracranial dural thickening with enhancement, which we image as “armored brain”, with venous sinus involvement in some patients, resulting in increased cranial pressure and venous infarction of the brain parenchyma. Typical case: Li xx, male, 31 years old. 5 years ago, the patient had intermittent attacks of headache with no obvious cause, located in the parietal and occipital areas, with distending pain of moderate nature and severe difficulty in still suffering, accompanied by nausea and vomiting once, relieved after taking oral “analgesic tablets”, and about 1 month later developed double vision without obvious vision loss, and consulted at the local hospital. He was diagnosed as “migraine” and was relieved by symptomatic treatment. Two months ago, the headache reappeared, and the headache extended to the whole headache, accompanied by right eye movement disorder, diplopia and vision loss, and the symptoms gradually worsened. He was hospitalized in our department for further consultation and treatment. After admission, blood and urine routine, biochemical, tumor markers, rheumatological and immunological indicators were all in normal range. Lumbar puncture cerebrospinal fluid examination: cranial pressure was measured at 250 mmH2O, leukocytes were mildly elevated (14×106/L), monocyte ratio: 78%, biochemically normal. MRV showed that the superior sagittal sinus was occluded. After admission, he was diagnosed with “hypertrophic dural meningitis”. After careful treatment by our treatment team, his headache was relieved significantly the next day, and his visual acuity disappeared in about one week.