The nervous system is a group of organs and structures, formed by nervous tissue, which are in charge of collecting and processing signals to later control and organize the rest of the organs, and thus achieve a correct interaction of the person with his environment.

The science in charge of studying all this complex structure is neurology. It tries to evaluate, diagnose and treat all kinds of disorders of the nervous system. For the evaluation and diagnostic tasks, a series of neurological tests have been developed that allow medical personnel to observe the functioning of this system.

What are neurological tests?

Neurological tests or exams are performed to examine whether the patient’s nervous system is functioning properly. These tests can be more or less exhaustive depending on what the doctor is trying to evaluate, as well as the age or condition of the patient.

The importance of these tests lies in their usefulness in detecting possible alterations early on , and thus eliminating or reducing, as far as possible, possible complications that may appear in the long term.

The first tests carried out by the clinician are physical tests, in which the nervous system is tested using hammers, tuning forks, flashlights, etc.

The aspects that are evaluated during this type of neurological exploration are

  • Mental state (consciousness)
  • Reflexes
  • Motor capacities
  • Sensory capabilities
  • Balance
  • Nerve function
  • Coordination

However, in the event that there is a suspicion of a possible alteration in any of these aspects, the medical professional has at his disposal a large number of specific and very revealing clinical tests when diagnosing any type of neurological problem.

Types of Neurological Tests

There are more than a dozen tests to evaluate the state of the nervous system, any of which will be more or less useful depending on what the clinician wants to look for.

Some of them are explained here.

Cerebral angiography

Cerebral angiography, also known as arteriography, is a procedure to locate possible vascular singularities in the brain . These irregularities range from possible brain aneurysms, blood vessel blockages or strokes, to brain swelling or malformations in the veins of the brain.

To detect any of these abnormalities, the doctor injects a radio-opaque substance into one of the brain’s arteries, making any vascular problems in the brain visible on the x-ray.

2. Electroencephalogram (EEG)

If what the doctor needs is to monitor brain activity, the EEG can be your reference test. During this test, a series of electrodes are placed on the patient’s head. These small electrodes carry the brain’s electrical activity to a device that reads this activity and converts it into a trace of the electrical record.

Likewise, the patient may be subjected to different tests in which he is presented with a series of stimuli such as lights, noises or even medication . In this way the EEG can detect changes in brain wave patterns.

If the medical professional finds it necessary to narrow down the search or make it more thorough, he or she may place these electrodes directly into the patient’s brain through a surgical incision in the patient’s skull.

The electroencephalogram is very interesting when diagnosing diseases or disorders such as

  • Brain Tumors
  • Psychiatric disorders
  • Metabolic disorders
  • Injuries
  • Brain or spinal cord inflammation
  • Seizure disorders

3. Lumbar puncture

Lumbar punctures are performed with the aim of obtaining samples of cerebrospinal fluid . This fluid is analysed to check for bleeding or hemorrhage in the brain, as well as to measure intracranial pressure. The purpose is to diagnose a possible brain or spinal cord infection such as those that occur in some neurological diseases such as multiple sclerosis or meningitis.

Usually, the procedure for this test begins by lying the patient on his or her side, asking him or her to place the knees next to the chest. The doctor then places the position between the vertebrae in the middle of which the puncture is to be performed. After administering a local anesthetic, the doctor inserts a special needle and removes a small sample of fluid.

4. Computerized Tomography (CT)

This test is part of the so-called brain scans , which also include MRI and PET scans. The advantage of all of them is that they are painless and non-invasive processes.

Thanks to the computerized tomography, fast and clear images are obtained of organs such as the brain, as well as tissues and bones.

Neurological CT can help to make differential diagnoses in neurological disorders with several similar properties. In addition, it is especially effective in detecting, among other things

  • Epilepsy
  • Encephalitis
  • Clots or intracranial bleeding
  • Brain damage from injury
  • Tumors and cysts of the brain

The test takes about 20 minutes, during which time the patient must remain resting inside the CT chamber. For this test, you must remain very still while the x-rays scan your body from different angles.

The end result is several cross-sectional images of the internal structure, in this case the internal structure of the brain. Occasionally, a contrast dye may be introduced into the bloodstream to facilitate differentiation of different brain tissues.

5. Magnetic Resonance Imaging (MRI)

Magnetic resonance imaging uses radio waves generated in a device and a large magnetic field to reveal details of organs, tissues, nerves and bones.

As with CT, the patient must lie still and be inserted into a hollow tube surrounded by a large magnet.

During the test a large magnetic field is generated around the patient and through a series of reactions a resonance signal is produced from various angles of the patient’s body. A specialised computer processes this resonance into a three-dimensional image or a two-dimensional cross-sectional image.

There is also functional MRI, in which images of blood flow in different areas of the brain are obtained thanks to the magnetic properties of the blood.

6. Positron Emission Tomography (PET)

In positron emission tomography the clinician can obtain images, in two or three dimensions, of the brain activity . This image is achieved through the measurement of radioactive isotopes injected into the patient’s bloodstream.

These radioactive isotopes attached to chemicals that flow into the brain are tracked as the brain performs different tasks. Meanwhile, gamma ray sensors scan the patient and a computer processes all the information, displaying it on a screen. Different compounds can be injected so that more than one brain function can be examined at a time.

PETs are especially useful when it comes to:

  • To detect tumors and infected tissues
  • Determine brain changes after substance use or injury
  • Evaluate patients with memory disorders
  • Evaluation of seizure disorders
  • Measuring cell metabolism
  • Showing blood flow

7. Evoked potentials

The evoked potential test can evaluate possible sensory nerve problems , as well as corroborate certain neurological conditions such as brain tumors, spinal cord injuries or multiple sclerosis.

These evoked potentials or responses calibrate the electrical signals that visual, auditory or tactile stimuli send to the brain.

Nerve damage is assessed using electrode needles. One pair of these electrodes measures the electrophysiological response of the stimuli on the patient’s scalp, and the other pair is placed on the area of the body to be examined. The clinician then notes the time it takes for the generated impulse to reach the brain.

Other tests frequently used for the evaluation and diagnosis of neurological disorders are

  • Biopsy
  • Single photon emission tomography
  • Doppler ultrasound
  • Myelography
  • Electromyography