I. Buoy’s syndrome alias: 1, spinal cord hemi-lateral damage syndrome; 2, spastic monoplegia syndrome; 3, hemi-lateral paraplegia syndrome. Outline: The main features are ipsilateral paralytic spasms below the level of spinal cord damage, hyperalgesia and vibration sensation, and loss of contralateral pain and temperature sensation. Aetiology: It is caused by spinal cord trauma and tumor compression. It can also be caused by trauma, infection, degeneration, and limited compression from vertebrae and spinal membranes. Ocular features: if the damage is located in the high cervical position, nystagmus may appear, occasionally the pupil is unresponsive to light, optic nerve atrophy. The degree of sensory damage depends on the spinal cord. Below the level of damage, there is ipsilateral deep joint sensation, loss of tendon and vibration sensation (the lesion involves only half of the spinal cord, resulting in ipsilateral spasm, failure, motor dysregulation, and tendon reflex hyperactivity). There may also be contralateral loss of nociceptive and temperature sensation, and some may have signs of segmental lower motor neuron paresis and segmental sensory deficits ipsilateral to the lesion. 2. Sphincter dysfunction. 3.Increased cerebrospinal fluid protein. 4.Vertebrogram, lumbar puncture cerebrospinal fluid examination and CT scan are helpful for diagnosis. Differential diagnosis: The clinical symptoms of this symptom resemble aortic coarctation and should be differentiated from it. Treatment: varies according to the cause, mainly for clear diagnosis and etiological treatment.