Sciatic Nerve – Anatomy

Sciatic nerve is on either side of the lower back. It is from the base of the lower back on both sides and runs through the pelvis along the back of the hip joint and thigh on both sides.

Sciatic nerve is a very important and one of the thickest nerves of the body. It is important for supplying motor function to the muscles of the leg and foot as well as taking sensations from the foot to the brain. Their critical function cannot be replaced by any other nerve or muscle.

Thereby, it is important that the sciatic nerve is functional and present. Very rarely, patients may have tumor involving the sciatic nerve, which may have to be excised and may lead to sacrifice of the sciatic nerve; unless otherwise, the sciatic nerve is never removed due to its critical function.

Sciatica can be treated by multiple types of doctors including primary care doctor, pain physician, sports physician, spine surgeons and orthopedic surgeons among others. The methodology to treat sciatica nonoperatively is essentially the same among all field. Operative treatment for sciatica can be done by an orthopedic surgeon or a spine surgeon or neurosurgeon.

Exercises are important and beneficial in patients with sciatica.  These patients should also do stretching of the nerve.  Exercises in the form of cord strengthening exercises, hip exercises are important not only in relieving pain, but also keeping the mobility and activity as well as the tone of the muscles in good shape.

Sciatica is not permanent, though it can be a recurrent. Patients who have had one episode of sciatica are at a higher risk of getting recurrence over the period of months and years. If the patient gets relieved with recurrent episodes of sciatica in shorter duration of time then it can be still treated nonoperatively.

Patient who have recurrent or prolonged episodes of sciatica, not relieved medications and physical therapy or patients who have neurological deficit or worsening pain, may need surgical treatment.

Sciatica or lumbar radiculopathy involving the L2, L3 and L4 nerve roots present as pain along the front of the thigh. The pain caused by pinching of the L2 and L3 nerve roots are present with pain along the upper and the middle thigh and may be associated with tingling and numbness. Pain due to the pinching of the L4 nerve root causes pain along the front of the lower thigh as well as over the knee and may have radiation into the inner leg.

Sciatica is caused due to nerve root irritation or compression. It usually happens on one side of the spine, but occasionally if the problem is on both sides or if the problem is in the midline then a patient can present with radiating pain, tingling, numbness with or without weakness on both sides also. Rarely, patients who have severe compression of the spinal nerve roots in the canal can present with cauda equina syndrome, which is an emergency and they present with involvement of both lower extremities or both legs.

Sciatica is caused due to irritation of the nerve root on either side of the lower back. This irritation is commonly caused due to disk herniation or osteophyte formation. Since most of the causes are due to degenerative spine disease, the degeneration of spine does have some genetic component, so indirectly sciatica can have a genetic or hereditary component, but there are many more factors associated with sciatica which are not genetic-related and it may be difficult to define how much genetics can play a role in sciatica.

In severe form of sciatica presenting with an emergency condition called cauda equina syndrome, in which there is severe compression with almost loss of all function of the nerve root, the patient may present with weakness of either or both lower extremities with or without involvement of bowel and bladder. Most of such patients will have loss of rectal tone leading to incontinence and loss of control of falls.

Swelling in the foot is most likely not related to sciatica because sciatica is caused due to neurogenic pain. They should try to find out and exhaust all other reasons for foot swelling, which may or may not be related to blood pressure, heart condition, liver condition, kidney condition and others. Occasionally, patients may develop neurogenic edema of the extremity due to involvement of the autonomic nervous system leading to compression of the nerve root.

Sciatica nerve innervates all the muscles of the leg below the knee joint as well as carries sensations from the skin of the leg and foot. It also supplies all the muscles of the foot and is crucial in ambulating.

Sciatica can get worse in the night, as the muscles relax while lying down, which causes the load to be more on the bones and the disk of the back. Convalescing sciatica pain may worsen while standing and walking also due to the dynamic change causing compression of the disk and leading to further protrusion. The patients who have instability and sciatica pain due to instability can also have worsening of pain due to the worsening of instability while standing and walking.

Sciatica pain or radiculopathy can be associated with decreased motor innervation to the muscles leading to weakness. This will also lead to muscle atrophy over the long run.

The upper extremity equivalent of sciatica is called cervical radiculopathy. The process is similar to sciatica. The nerve root in the neck or the cervical spine is inflamed and irritated most commonly due to disk herniation in the neck. This leads to radicular pain along the arm and the forearm and to the hand depending on the nerve root, which is compressed or irritated.

If the sciatica pain is under control or mild then doing workout which should include stretching as well as strengthening muscles especially of the back may be helpful in decreasing the pain and recovering from sciatica.

Sciatica damage to L5 nerve root and S1 nerve root maybe associated with ankle weakness and occasionally foot drop. Such patients usually have a severe form of nerve damage. Treatment could include management of the radiculopathy, medications, physical therapy with or without surgery. Surgery may be more often needed in such patients especially if the neurological deficit is still evolving, so as to decrease or elevate the further neurological deficit as well as to optimize the recovery.