pain sensation, and temperature sensation are lost, while sense of touch and proprioception (sense of position in space) remain intact. These differences are due to the relative locations of the spinal tracts responsible for each type of function. Brown-Séquard syndrome Brown-Séquard syndrome occurs when the spinal cord is injured on one side much more than the other. It is rare for the spinal cord to be truly hemisected (severed on one side), but partial lesions due to penetrating wounds (such as gunshot or knife wounds) or fractured vertebrae or tumors are common. On the ipsilateral side of the injury (same side), the body loses motor function, proprioception, and senses of vibration and touch. On the contralateral (opposite side) of the injury, there is a loss of pain and temperature sensations.Spinothalamic tracts are in charge for pain and temperature sensation and because these tracts cross to the opposite side and above the spinal cord there is loss on the contralateral side. Posterior spinal artery syndrome Posterior spinal artery syndrome (PSAS), in which just the dorsal columns of the spinal cord are affected, is usually seen in cases of chronic myelopathy but can also occur with infarction of the posterior spinal artery. This rare syndrome causes the loss of proprioception and sense of vibration below the level of injury while motor function and sensation of pain, temperature, and touch remain intact. Usually posterior cord injuries result from insults like disease or vitamin deficiency rather than trauma. Tabes dorsalis, due to injury to the posterior part of the spinal cord caused by syphilis, results in loss of touch and proprioceptive sensation. Conus medullaris and cauda equina syndromes Conus medullaris syndrome is an injury to the end of the spinal cord the conus medullaris, located at about the T12–L2 vertebrae in adults. This region contains the S4–S5 spinal segments, responsible for bowel, bladder, and some sexual functions, so these can be disrupted in this type of injury. In addition, sensation and the Achilles reflex can be disrupted. Causes include tumors, physical trauma, and ischemia. Cauda equina syndrome may also be caused by central disc prolapse or slipped disc, infections such as epidural abscess, spinal haemorrhages, secondary to medical procedures and birth abnormalities. Cauda equina syndrome (CES) results from a lesion below the level at which the spinal cord ends. Descending nerve roots continue as the cauda equina at levels L2–S5 below the conus medullaris