Neurologist

A physician who specializes in treating diseases and disorders associated with the nervous system that includes spinal cord, brain, associated nerves and muscles. To be a neurologist, one should have completed four years of graduation, four years of medical school, one year of internship in internal medicine/surgery and three years of neurology residency. They can further hold a sub-specialization in stroke, epilepsy etc. They should also be certified by a recognized board.

A neurologist conducts

• Neurological assessment of the nerves related with the neck and head.
  
• Checks on movement of the muscles and the strength of the same.
  
• Checks on ambulation, balance and reflexes.
  
• Checks for sensation, speech, language, memory, and various other cognitive skills.
  
• They ask for diagnostic tests in few patients such as CAT scan, MRI, EEG, EMG/NCV and lumbar puncture and analyze those results in relation to the disorder of the patient.
  

• With latest CAT scans understanding the diseases have become a lot easier.
  
• MRI (magnetic resonance imaging)/MRA (magnetic resonance Angiography) gives a better understanding of the structures.
  
• NCV (nerve conduction velocity) give a better understanding of the nerves.
  

Nerve Conduction Study

A medical diagnostic tool used to evaluate the ability of the motor and sensory nerves for electrical conduction is the Nerve conduction study. Nerve conduction studies are performed by medical specialists in neurophysiology, physiatry and neurology with sub-specialization in electro diagnostic medicine. The common measurement made during this test is called Nerve conduction velocity or NCV. This is conducted to determine the damage and destruction caused to nerves.

Procedure

The procedure is to stimulate the nerve with surface electrode patches attached to the skin. Two electrodes are placed on the skin over the nerve. One electrode stimulates the nerve with a mild electrical impulse. The resulting electrical activity is recorded by another electrode. This testing is repeated in about 2 - 3 places along the arms or legs. After the procedure, the nerve conduction speed is calculated by measuring the distance between electrodes and the time it takes for electrical impulses to travel between electrodes.

The nerve conduction velocity (speed) is then calculated by measuring the distance between electrodes and the time it takes for electrical impulses to travel between electrodes.

A related procedure that may be performed is electromyography (EMG). An EMG measures the electrical activity in muscles and is often performed at the same time as NCS. Both procedures help to detect the presence, location and extent of diseases that damage the nerves and muscles.

Prior to the procedure

This study does not require any fasting or sedation prior to the procedure. But body temperature must be maintained before and during the procedure as low body temperature slows nerve conduction. Keep the doctor informed in case of any medicine or herbal supplements you might be taking. You must stop using lotions or oils on your skin a few days before the procedure. Based on your medical condition, the doctor may request any other specific preparation.

During the procedure

A nerve conduction study is performed as an outpatient procedure although procedures may vary depending upon the condition and doctor's practices. The study is performed by a neurologist although a technologist may perform portions of the test. During the procedure, the patient is asked to remove any clothing, jewelry, hairpins, eyeglasses, hearing aids, or any other metal objects that may interfere with the procedure.

The patient is asked to either sit or lie down for the test. A recording electrode is attached to the skin over the nerve with a special paste. A stimulating electrode is placed at a known distance away from the recording electrode. The nerve is stimulated by a mild and brief electrical shock through the stimulating electrode. You might experience minor discomfort for a few seconds. The patient senses rapid tingling in the area. The stimulation of the nerve and the response are displayed on an oscilloscope.

What does the test results indicate?

Generally, the nerve conduction velocity would be around 50 to 60 meters per second. But it tends to vary from person to person and from one nerve to another.

The speed of the nerve conduction study is related to the diameter of the nerve and the degree of myelin sheath (which is a type of insulation) around the nerve. While a normally functioning nerve will transmit a stronger and faster signal, a damaged nerve will be slower. The larger the wire, the better the insulation and more consistent and stronger will be the signal.

If results are abnormal, they may be due to some sort of neuropathy or damage to the nerve resulting from a traumatic injury or nerve. Sometimes, other diseases may also cause the impulses to slow down. It could be due to conduction block that is an obstacle to the impulse within the nerve or due to demyelination or damage to the myelin sheath.

Why nerve conduction study?

Nerve conduction study is done along with EMG to differentiate a nerve disorder from a muscle disorder. While nerve conduction study detects whether the nerve has any problem, EMG detects whether a muscle is functioning properly in response to the nerve's stimulus. Whenever there is any neurologic injury or disorder, nerve conduction studies often combined with needle electromyography measure are used. This helps in identifying cause for any pain or weakness in the limbs from spinal nerve compression or injury.

Nerve conduction studies are used primarily for evaluation of numbness, tingling and burning or weakness of arms and legs depending upon the part of the body the symptom is present. Physical examination by the doctor and patient's history help to direct the investigation. A number of disorders are diagnosed by nerve conduction studies - carpal tunnel syndrome, Gullian-Barre syndrome, peripheral neuropathy, spinal disc herniation, ulnar neuropathy and others.

Risks of the procedure

Although the voltage of electrical pulses used in this study is quite low, there may be risks depending upon specific medical conditions. Certain factors such as damage to the spinal cord, severe pain before the test and body temperature may affect the test. In case you are using cardiac defibrillator or pacemaker, adequate precautions need to be taken.

Guillain Barre Syndrome

Guillain Barre syndrome or GBS (also known as infectious polyneuritis) is a rare disease that affects the peripheral nervous system. This condition arises when the body's immune system attacks the peripheral nerves after an infection or an immunization. Guillain-Barre syndrome affects the myelin sheath that covers nerve cells. The loss of myelin is called as demyelination. It causes progressive muscle weakness usually starting in the lower extremities and often ascending to the muscles involved in respiration and usually reversible paralysis which develops over days or up to four weeks and lasts several weeks to several months.

Guillain-Barre syndrome can be life-threatening. Typically GBS follows an infection such as sore throat, Hodgkin's disease or other bacterial diseases. Sometimes surgery can trigger GBS. A severe attack of Guillain-Barre syndrome can leave a patient totally paralyzed. The patient has difficulty in breathing and sharp fluctuations in blood pressure and pulse rate.

Symptoms may start with muscle weakness in the legs first, then it progresses to the arms and face. Paresthesia (abnormal skin sensation like tingling) often occurs at the same time. Again the disorder doesn't restrict its action to one side alone. This affects both sides of the body and may involve paralysis of the muscles that control breathing.

Symptoms of Guillain-Barre syndrome include severe numbness and weakness in the limbs. It can result in loss of feeling and movement and temporary paralysis. There may be bouts of headache and vomiting. Symptoms such as tingling in the limbs and muscle weakness are characteristic of GBS.When Myelin (sheath that wraps around nerves), which is responsible for speed and efficiency of impulses traveling through those nerves, suffers damage, nerve communication is disrupted. The most common preceding infections are cytomegalovirus, herpes, Epstein-Barr virus and viral hepatitis. A gastrointestinal infection with the bacteria Campylobacter jejuni is also common. Patients with infections that impair body defense system like lymphoma, systemic lupus erythematosus or AIDS, have a higher than normal risk of GBS.

Diagnosis Early diagnosis is vital to the treatment of Guillain-Barre syndrome. Diagnosis of GBS is primarily to look for a particular cluster of symptoms which start with progressively worse muscle weakness and then paralysis. A spinal tap is another diagnostic mechanism that helps to determine the pressure of the cerebrospinal fluid (CSF) that bathes the brain and spinal canal. This fluid is obtained by a lumbar puncture, which upon examination will reveal a greater than normal quantity of protein but with normal numbers of white blood cells and a normal amount of sugar. A nerve conduction velocity (NCV) test can aid the doctor in diagnosis of Guillain-Barre syndrome. Electromyography helps in identifying the extent of damage to the neurological system. Electrodiagnostic studies may show slowing or a block of conduction in nerve endings in parts of the body other than the brain.

Treatment If diagnosed within the early weeks, patients suffering from Guillain-Barre syndrome can recover in good time. Although there is no direct treatment for Guillain-Barre syndrome, palliative care, and symptom management is usually attempted. Careful attention must also be paid to the amount of fluid intake. Blood pressure, heart rate and heart rhythm also must be monitored. Plasmapheresis and high-dose immunoglobulin therapy are used to treat Guillain-Barre syndrome. Plasmapheresis consists of withdrawing the patient’s blood, passing it through an instrument that separates the different types of blood cells and returning all the cellular components along with either donor plasma or a manufactured replacement solution. This process is resorted to rid the blood of the substances that are attacking the myelin. Severe cases of GBS need hospitalization. Critical body functions need to be monitored during the recovery of the nervous system.

Prognosis Usually about 85 % of cases of GBS recover with little complications. But some 30 % adult cases and a larger percentage of children never regain their functions completely. Elderly patients and patients who had their worst symptoms within the first 7 days have a higher risk of dying due to complications.