What is it
An electroencephalogram or EEG is a diagnostic test to measure the electrical activity in the brain. Small electrodes coated with a conductive paste are placed on the scalp and the electrical impulses generated by resting neurons are measured. The patient will be asked to breathe in and out deeply and be subject to potostimulation, audio and visual stimulation, amongst others to ontain the data.
What is its purpose
This test is intended to assess changes in brain electrical activity. It can detect changes throughout the brain, detecting lesions (tumors, bleeding, encephalitis, trauma …) and diffuse lesions (toxic, metabolic, infectious …).
This test is done to patients presenting with symptoms of impaired consciousness (drowsiness, stupor, coma), loss of intellectual faculties (memory loss, dementia) or suspected epileptic siezures. In children, especially newborns, it is crucial both to detect existing conditions as well conditions that might affect brain growth and maturation. In patients with other symptoms (headaches, nervousness, instability …), the EGG serves as a complementary diagnostic test when used with other methods of imaging such as MRI or CAT scan).
How is it done
It is a simple procedure with little risk; the only factor to consider would be if the patient has an allergy to any component material of the test (conductive paste, metal electrodes …). The test typically takes 15 to 25 minutes, although performing brain scans of 24 hours or even monitoring the patient for several days, collecting data whilst asleep, is possible should your doctor feel it is necessary.
No special preparation is required before the test. The patient must sit on a reclining chair or lie on a bed in the area set up for the test; Electrodes that amplify the electrical signal to the brain are placed on the scalp and attached to a computer. Brain activity will be monitored whilst at rest, with eyes open and closed, and also when the brain is being stimulated (hyperventilation, auditory or visual stimulation, etc.).
What is it
Electromyography is a medical test used to determine the state of the peripheral nervous system and muscles using a thin needle with an electrode. To do this, the electrical activity generated by muscle fibres is measured, to assess their status and that of the nerves that control them
What is its purpose
This test is used to diagnose the conditions involving loss of strength, weakness or loss of muscle mass, either in a specific area or in the upper or lower limbs. Several of the diseases that can be diagnosed through electromyography are neuropathy, amyotrophic lateral sclerosis, myopathy or polyneuropathy, among others. In addition, this test is also very useful in various specialties such as neurology, traumatology and endocrinology, as it pinpoints the injured area and determines if the injury is to the muscle, nerve or nerve root
How is it done
No advance preparation is needed for the test; it is even recommended that the patient is not fasting at the time of the test. The duration is approximately half an hour, depending on the muscle or nerve to be examined. To perform the test, the patient should be relaxed, sitting or lying down. A needle is inserted into the area to be studied, and very low voltage electrical shocks are administered, inducing a muscle contraction. The data is collected through a device called an oscilloscope, which will produce graphs showing muscle and nerve at rest and and when exercising.
This test is very simple with hardly any contraindications, although the insertion of the needle may be uncomfortable. This may also cause minor bleeding, so patients with clotting disorders or anticoagulant treatments should be very cautious and, above all, notify the medical staff beforehand
What is it
Brain Mapping is an electroencephalogram that is done using much more precise and advanced techniques to analyze the electrical activity of the brain in three dimensions, ituses complex mathematical formulas, interpreted by a computer to represent in map form the distribution through the cerebral cortex of each electrical function.
What is its purpose
Brain mapping is based on the electroencephalogram, but using a monitor is used to view the results. It offers images of the brain through established patterns, these allow any changes such as possible injuries and electrophysiological alterations in the central nervous system to be observed.
Mapping has become an important tool for the diagnosis of various neuropsychiatric disorders and other problems such as such as depression, epilepsy, hyperactivity, insomnia, stress, dementia.
Sleep Study
What us it
Polysomnography is a sleep study, that analyses simultaneously the various biophysiological changes that occer whilst the patient is sleeping, to provide a more accurate diagnosis of possible alterations that can affect sleep.
What is its purpose
The main function to diagnose various sleep disorders, such as obstructive sleep apnea, snoring, chronic and acute insomnia, restless leg syndrome, narcolepsy, night terrors, nightmares or sleepwalking .
By analyzing various parameters, polysomnography measures the various cycles and stages of sleep, obtaining a record of values (oxygen levels in the blood, brain waves (EEG), respiratory rate, electrical activity of muscles, eye movements, heart rate, etc.), which are then interpreted by a specialist to determine if the results are normal or have some kind of anomaly.
How is it done
To perform a polysonmograph the pacient must sleep in the laboratory where the sleep test is to be done.
Before the test starts a series of electrodes are placed on the patient’s head and an oximeter is placed on the index finger so the patient can be monitored. Both of these are placed so that the patient will remain comfortable and able to sleep as normal.
A specialist monitors the signals generated by the electrodes, both whilst the patient is awake with eyes closed and whilst they are asleep. The signals generated by the electrodes are registered on a computer and any anomaly detected recorded.
There are several techniques for polysomnography, as they can be done in the day or night and with or without CPAP equipment.
(brainstem auditory, visual, multimodal and somatosensory)
What is it
It is a neurophysiological examination that analyzes the function of acoustic, visual and somatosensory sensory system through brain responses triggered by some known and controlled stimuli. This allows the analysis of the operation of the various parts of the brain structures involved in perception and cognition.
What is its purpose and how is it done?
Evoked potentials involverepeated stimulation by the same stimulus, the results are collected on a computer and a graph is produced showing an average of the results in wave form.
According to the system to be evaluated, there are various evoked potentials employing various techniques:
Visual: this studies the state of the optic nerve and usually carried out on an illuminated screen showing a chess board where the squares change between black and white. Each change is registered by the retina and transmitted to the brain, which will be recorded by a series of sensors and plotted on the computer monitor.
Hearing: this analyze the response of the cochlear nerve, brain stem and the auditory cortex, without any collaboration from the patient. To do this, a headset produces a “click” and this causes a series of waves due to the passage of the stimulus through the different structures used.
Somatosensory: the most used are the median nerve in the arm and tibial nerve in the leg, and its aim is to monitor the status of the sensory pathways. Using sensors that apply an electrical stimulus, repeated stimulation is applied to one of the aforementioned nerves to provoke the signals emitted by the muscle.
What is it
The Multiple Sleep Latency Test is a test that allows the study and recording of entry into sleep latency and entry into REM sleep, ie, indicates the time it takes the patient falls asleep.
What is its purpose
The multiple sleep latency test (MSLT) tests for excessive daytime sleepiness and allows the evaluation and diagnosis of various sleep alterations such as narcolepsy, sleep apnea and abnormal hypersomnia
¿Cómo se realiza?
This test is performed in the sleep unit, early in the morning a series of electrodes are placed on the patient. The patient, should take 5 naps of 20 minutes throughout the day, separated by two hour intervals during which the patient must stay awake.
Subsequently, the specialist will review all records obtained during the test and collected through a computer, allowing them to analyze the results and obtain an accurate assessment