In the most common form, length-dependent peripheral neuropathy, pain and parasthesia appears symmetrically and generally at the terminals of the longest nerves, which are in the lower legs and feet. Sensory symptoms generally develop before motor symptoms such as weakness. Length-dependent peripheral neuropathy symptoms make a slow ascent of leg, while symptoms may never appear in the upper limbs; if they do, it will be around the time that leg symptoms reach the knee.  When the nerves of the autonomic nervous system are affected, symptoms may include constipation, dry mouth, difficulty urinating, and dizziness when standing . 
For the majority of people, sciatic nerve pain is caused by a herniated disc in the back, which means a disc in the spine develops a slight crack or tear. A herniated disc sticks out into the spinal canal, which means it alters chemical messages that are sent via the nerves to the limbs. If a spinal disc protrudes out in a certain area, it can “pinch” the sciatic nerve, which is one of the main channels of communication between the spine and legs. The sciatic nerve connects smaller branches of nerves that run through the spinal canal, from the pelvis down the legs and into the ankles and feet. ( 9 ) Herniation causes symptoms by putting pressure on the spine.
Medicines are commonly prescribed for the treatment of sciatica, but evidence for pain medication is poor.  Specifically, low-quality evidence indicates that NSAIDs do not appear to improve immediate pain and all NSAIDs appear about equivalent.    Evidence is also lacking in use of opioids and muscle relaxants by usual means.  In those with sciatica due to piriformis syndrome, botulinum toxin injections may improve pain and or function.  There is little evidence for steroids, either epidural or by pill.   Low-quality evidence supports the use of gabapentin for acute pain relief in those with chronic sciatica.