After a clinical examination, the specialist makes diagnostic hypotheses, which are confirmed, denied and / or enriched through instrumental examinations.
The doctor may request anatomical examinations (which allow the visualization of the pathology) or physiological examinations (which allow to record the anomalies in the passage of electrical flow in the central and / or peripheral nervous system).
What are the anatomical exams?
Radiography is a diagnostic test that is carried out through the use of X-rays, which pass in a single direction providing a generally frontal or lateral image of the back or spine. They have the advantage of showing the structure of the spine under load, standing up.
They can be standard (immobile) or dynamic (in flexion, extension, etc.). The latter provide information on the mobility of the various segments of the spine.
It is an exam that lasts a few moments.
Computed tomography is a diagnostic technique that allows you to examine the body by images through X-ray beams in the affected area; the images that emerge are re-elaborated by a computer, which reconstructs them three-dimensionally.
Sometimes it can be done through the use of a contrast agent (iodine) which is injected intravenously.
To perform the exam, the patient must lie down on a bed that slides inside the machine, and must remain still for the entire duration of the exam, which is usually a few minutes.
Magnetic resonance imaging (MRI) is a diagnostic technique that provides images of the human body using magnetic fields, without exposing the patient to ionizing radiation.
Sometimes it can be done through the use of a contrast agent (Gadolinium) which is injected intravenously.
To perform the examination, the patient must lie down on a bed that slides inside the machine, and must remain still for the duration of the examination. The duration of the exam is on average 40 minutes.
It is a painless examination and the only annoyances it can cause derive from the sense of claustrophobia and the loud noise caused by the machine.
Patients with cardiac pacemakers or neurostimulators, or those who have metallic foreign bodies inside their body, cannot perform the test.
For some years there has been dynamic magnetic resonance that allows you to see the spine in its physiological conditions (standing or moving) in order to reproduce the positions that cause pain, identifying any pathologies not highlighted by traditional examinations.
What are the physiological tests?
Through the electroencephalogram (EEG) the electrical activity of the brain is recorded through external electrodes; this recording is represented by a series of waves reproduced on a screen and printed on paper or transferred to an electronic medium.
The standard EEG lasts about 20 minutes while the dynamic EEG (Holter) records the brain's electrical activity for 24 hours. In the field of neurosurgery, this examination is very useful for the detection and control of epilepsy or the suspicion of epileptic seizures. It is an absolutely painless examination. It is generally interpreted by a neurologist doctor while it is performed by a technician.
This technique is often used during brain surgery in order to monitor the brain's electrical functions live.
Electromyography (EMG) is an exam that allows the study of the nerves and muscles of the upper and lower limbs through the use of electrodes that record and transfer muscle and nerve activity on a graph. EMG studies the peripheral nervous system. It is interpreted by a neurologist and generally lasts between 30 and 60 min.
In the field of neurosurgery, this examination is especially useful for the diagnosis of radiculopathies (sciatica, cruralgia, cervicobrachialgia) ((Mettre liens vers ces pathologies)) or carpal tunnel syndrome. It allows to direct the diagnosis towards a cervical or lumbar root in particular. The electrical stimuli can create slight discomfort.
This technique is often used during surgery on peripheral nerves to monitor the electrical functions of those nerves.
Evoked potentials (PEM, PESS, PEV, PEA, etc.)
The evoked potentials are tests that allow to study the passage of the nervous influence between the central nervous system and the peripheral one (the limbs, eyes, ears ...) in one direction or the other, through the use of electrodes that record and transfer muscle and nerve activity on a graph.
Motor Evoked Potentials (PEMs) study the pathway between a stimulus on the motor cerebral cortex and the muscles of the limbs, via the spinal cord.
Somato-Sensory Evoked Potentials (SSPE) study the nerve pathways between a peripheral stimulus (on the limbs) and the response on the cerebral cortex, via the spinal cord.
Visual Evoked Potentials (VEPs) study the pathways between the occipital visual cortex (back of the brain) via the optic nerve which is stimulated with visual impulses via a screen.
Acoustic Evoked Potentials (PEA) study the auditory pathways between the brain and external auditory stimuli.
These techniques are often used during surgery, particularly on the spinal cord, in order to monitor the electrical functions between the brain and the 4 limbs.
Eye exam (field of view)
The visual field allows to represent on a grid the portion of space that the patient can see while looking forward, as well as to quantify and evaluate the sensitivity of the retina.
It is a test that is done in the dark, focusing on one eye at a time. As in many eye exams, the patient must rest his chin and forehead on a support, and must look at a fixed point, a sort of dome in which light stimuli of varying intensity flow. The patient must press a button when he can perceive the light stimulus.
In the field of neurosurgery, this examination is useful for the detection and control of visual field alterations due to lesions on the pathway of the visual pathways (optic nerves, optic chiasm, brain fibers) such as adenoma of the pituitary gland.
It is a painless exam that lasts a few minutes.
What tests to perform before the neurosurgical visit?
It is advisable to carry out a minimum of diagnostic tests already before the specialist visit, in order to guide the specialist in the right diagnosis and / or treatment. These examinations must be as recent as possible and the patient must carry them with him at each visit.