Spontaneous intracranial hypotension (SIH) is an uncommon syndrome with postural headache as the main symptom and CSF pressure less than 60 mmH2O in the lateral position. It is more common in middle-aged women (the ratio of men to women is about 1:3), and it is a benign process. Clinical manifestations 1. Postural headache, headache is mostly located in the frontal and occipital areas. When sitting or standing, the headache is severe, and when lying down, the headache disappears or is reduced. 2.Visual symptoms: abducent nerve palsy, transient blurred vision, visual field defects on both sides, photophobia, diplopia, transient black lemon, etc. 3.Auditory symptoms: auditory hypersensitivity, hearing loss, tinnitus, etc. 4.Vertigo, nausea, vomiting, general weakness. 5.Physical examination: Patients often have cervical ankylosis. A few patients may have the above-mentioned cranial nerve manifestations, such as trigeminal nerve, facial nerve, and oculomotor nerve. Auxiliary examination 1. CSF examination: the pressure is less than 60mmH2O, or even 0 by lumbar puncture, or aspiration with a needle is required. Laboratory tests can be normal, but there can also be an increase in cell count and protein. Red blood cells can be as high as several thousand/dl, white blood cells are a few tens to hundreds/dl, and protein content can be increased to 500mg/dl. 2. Cranial CT: shows narrowing of the ventricular system, brain pools and brain sulci. The changes of lateral ventricle and suprasellar pool are especially obvious. Some patients can also see subdural fluid. 3.Head MRI: It is valuable to diagnose SIH after enhancement. The most common change is diffuse dural signal enhancement, and in some cases there may be meningeal thickening. 4. MRI of the spinal cord: It also shows enhanced signal in the dura mater of the spinal cord after enhancement and subdural and/or epidural effusion. 5.Isotope brain pool imaging: It can be found that the nuclei slowly deepen along the longitudinal axis of the spinal cord and accumulate in the bladder at an early stage, while appearing less in the cerebral convexity. Part of the isotope can be seen to accumulate in the local intervertebral space, suggesting a local CSF leak. 6.CT myelography: It shows CSF leak more clearly and can locate it more precisely. CSF leaks in the spinal cord are mostly seen in the cervical medulla, cervical dilatation or thoracic medulla. SIH etiology: choroid plexus vasodilatory dysfunction causing reduced or stopped CSF secretion; choroid plexus vasospasm; small defects in the meninges themselves. The pathogenesis of SIH: low cranial pressure causes “brain sink”; the protective cushioning effect of CSF on the brain and spinal cord is reduced, so that the pain-sensitive tissues at the base of the skull are stretched and headache is produced; the decrease in the amount of CSF causes compensatory dilation of the meningeal vessels, resulting in persistent headache. Involvement of adenosine: reduction of CSF activates adenosine receptors, dilating intracranial veins and causing headache. Complications of SIH: chronic subdural hematoma, which can be recurrent and requires surgery; chronic subdural effusion; displacement of cerebellar tonsils: similar to chiari type I malformation Diagnosis of SIH : 1. Postural headache; low intracranial pressure by lumbar puncture, increased CSF cell count, protein. 2. CT: narrowing of the ventricular sulcus; 3. MRI: enhancement of meningeal signal and “brain subsidence”. 4. CT myelography and isotope brain pool imaging: CSF leakage can be shown. Treatment of SIH: 1. Bed rest: lying down or head down and feet up. 2. 2. Drink plenty of water: 5000ml/d; intravenous rehydration: 3500~4000ml (saline 1000ml, 5% glucose solution 2800~3000ml). 3. Intrathecal rehydration or epidural rehydration: 15~30ml/qod of Ringer’s solution or saline. 4. Hormone: It helps water and sodium retention and reduces the inflammatory response after cellular protein exudation in CSF, which can relieve the symptoms, and some people think it is ineffective. 5. Distilled water intravenous injection, 20-40ml/qd or qod, 5-7 times; 6. Sodium benzoate caffeine 500mg IV or theophylline 300mg Tid; 7. Lumbar puncture epidural blood spot (EBP), after local anesthesia take L3-4 gap into the needle to the epidural cavity, use a plastic syringe to take venous blood 10 -30ml of autologous blood is slowly injected into the epidural cavity to form EBP. 8. 5% carbon dioxide is inhaled to increase cerebral blood flow significantly and relieve symptoms. 9. Symptomatic treatment: analgesia, sedation, antiemetic.