The Neurological Assessment

A neurological assessment includes several exams, tests and procedures which are used to make the diagnosis of nervous system diseases. So what can you expect when undergoing neurological evaluations? Every condition is different and therefore the assessment will vary considerable. However, there are some general tests and exams which many neuro patients will undergo. Here is an overview of some of these common parts of a neuro assessment.

The Neuro Assessment

Neurological Evaluation

A neurological evaluation is a clinical assessment of the nervous system aimed at detecting any abnormalities which may be related to a nervous system disease. An initial neurological assessment may be conducted by a primary care physician such as an internal medicine doctor or family practitioner, but a complete and thorough assessment is generally conducted by a specialist in the area of neurological disorders such as a neurologist or neurosurgeon, depending on the disorder in question.

The neurological evaluation is a complete assessment of the nervous system but may be focused on parts of the nervous system related to symptoms with which the patient is presenting. For example, a patient presenting with back pain and leg symptoms may have a focused neurological assessment which spends more time evaluating the legs and back while a patient presenting with facial weakness and difficulty with hearing may have a quite different assessment.

An evaluation of the nervous system for nervous system diseases can include three general components, a subjective review of the patient's presenting complaints and medical history, a neurological exam and diagnostic testing focused on the nervous system.

The review of the complaint and medical history is common to all medical assessments. The patient is questioned by their physician about all aspects of their complaint or symptoms as well as details of their past medical history, family history, medications, allergies, social history and a review of other symptoms. This helps the physician understand the complaint as well as other medical conditions and other aspects of the patient's history which may impact the current problem in one way or another.

The neurological exam is a physical examination which is focused on the nervous system. It is aimed at determining any signs or symptoms related to the nervous system or its function. The complete nervous system examination is quite detailed with several areas of the body examined. We will not list every physical exam test and maneuver here but the general sections of the complete neurological exam are described on the neurological exam page.

Finally, after these assessments by the physician, diagnostic testing is used in some cases to help detect a suspected or concerning pathology. This varies from patient to patient and from disease to disease. However, common tests or studies used to help diagnose nervous system diseases include x-rays, MRI scans, and CT scans of the head and/or spine. Additionally, nerve conduction studies, electromyelography (EMG), eletroencephalograms (EEG), blood tests, lumbar puncture (spinal tap) can also be used in some select instances. There are other tests, procedures or studies which are performed in more specific examples. For example, in a patient with a tumor, a biopsy or removal of the tumor is sometimes required to make the definitive diagnosis.

All of these parts of the neurological evaluation can help the physician to determine the most likely diagnosis as well as the most appropriate course of action. Determination of prognosis and treatment for the disease rely on this evaluation and the data it supplies. Every patient and disease is different and the specific aspects of one patient's evaluation may differ somewhat from another.

Neurological Exam

A neurological exam is a physical examination conducted by a health care provider which is focused on the nervous system. It is a common part of a complete neurological assessment as may be conducted by various physicians, most commonly a neurologist or neurosurgeon. The goal of the examination is to detect any signs or symptoms related to the nervous system and its functioning.

The neurological exam can be conducted by anyone, including primary care providers such as family practitioners and internal medicine doctors. However, it is most commonly part of a neurological evaluation by a physician specializing in diseases of the nervous system, such as a neurologist or a neurosurgeon.

What Are the Parts of a Typical Neurological Exam?

* Behavioral, Cognitive and Mental Status: This part of the neurological evaluation helps to determine the higher functioning of a patient's brain. It is an assessment of their mental status, or level of alertness and consciousness, as well as their higher functions of memory, reasoning, logic and general behavior. While some of this overlaps with a psychological assessment, it is, at least in part, a part of the complete neurological examination.
* Head and Neck Exam: Because the brain and spinal cord are in the head and neck, a general examination of the head and neck for malformations, abnormal anatomy, masses and other findings is often undertaken.
* Cranial Nerve Exam: There are 12 cranial nerves which are nerves that originate in the head, coming off the brain and brain stem. The examination of these nerves and their functions is complex but includes areas such as smell, vision and eye movements, facial sensation, reflexes and movement, hearing, taste, tongue and palate movements and even movements of the head, neck and shoulders.
* Motor Exam: This part of the examination tests the motor function, or movement, of the major muscle groups, most notably in the shoulders, arms, hips and legs. The muscles are tested for mass, muscle tone, and strength.
* Reflex Exam: Various reflexes are tested throughout the body. While these can indicate problems with sensation and/or motor function, they can also reveal other aspects of nervous system dysfunction as well.
* Coordination and Gait: Coordination testing and evaluating a patient's gait reveal much about various aspects of their nervous system. While they involve motor function they also reveal aspects of other more subtle components of brain function which controls these things.
* Sensory Exam: Finally, the sensory exam part of the neurological exam evaluates the sensation of the patient. This includes not just normal touch but also pain and temperature and sensation of limb position and movement.

The neuro exam is just one part of a complete neurological assessment. While in some patients the complete neurological exam is undertaken, in others a focused exam is used to evaluate only those aspects of the nervous system which are most concerning because of the patient's presenting complaints or symptoms. While some diagnoses can be made simply on the basis of the physical examination, most require further testing or studies, such as a CT scan or MRI scan, to make or confirm the diagnosis.

Neurological Tests

CAT Scan (CT Scan or Computed Axial Tomography)

A CAT scan, or Computed Axial Tomography or CT scan, is an imaging study which uses x-rays to produce images of the internal parts of the body. It is commonly used to visualize the brain and other structures in the head to investigate diseases of the brain. They can be used to visualize other body parts as well, including the chest, abdomen and pelvis.

A CT scanner, like a brain MRI scanner, is a large donut-shaped device that the patient is place into on a moving table. Rather than a plain x-ray machine which shoots a single burst of x-rays through a body part, a CAT scan rotates around the patient while using x-rays to take several radial images. Through computer manipulation, these multiple images are recombined into cross-sectional images of the inside of the body which gives much more subtle and detailed information than a plain x-ray alone. These images can then be viewed by a radiologist or other physician to interpret.

X-rays are high energy photons (the energy "packets" of electromagnetic energy, similar to light but not in a visible wavelength) similar to gamma rays that pass through the body. More dense tissues such as bone block most x-rays while softer tissues let more x-rays pass completely through. Therefore, the image produced by an x-ray and CT scan is based on the density of tissues. Bones show up brightest while air is the darkest.

Because a CAT scan brain scan uses x-rays, the patient is exposed to some radiation. However, because most patients are not exposed to many over a lifetime and because the exposure is small, they are generally considered very safe for general use. They do not cause any pain or discomfort but some patients complain of claustrophobia while in the round scanner. However, most CT scans are very fast, faster than a typical MRI scan.

Occasionally a brain CT scan is performed with an injection of a contrast agent. Contrast is basically a dye that is injected into a vein which is very dense and therefore shows up brightly on the CT scan. It can help to visualize blood vessels and may make some diagnoses, such as some brain tumors, easier to see.

What Is It Used For?
CT brain scans produced a quick and relatively inexpensive, compared to MRI, image of the brain and surrounding structures. It does not have the high resolution and special imaging types that MRI is capable of but it has advantages over MRI in a couple areas.

For one, CT is very good at showing detail of bone anatomy and pathology. Therefore, for identifying fractures and bony spine abnormalities it is superior to MRI.

CT is also very good at demonstrating acute bleeding. It can clearly show bleeding associated with trauma, rupture of an intracranial aneurysm or other causes. Therefore, CT is often used in the setting of trauma and some other hemorrhagic conditions.

For other pathologies, like ischemic stroke and brain tumors for example, generally MRI is preferred for its better anatomic detail and resolution. However, in some centers MRI is not as easily available or CT will be performed first because it is cheaper and faster as a basic screening test.

While MRI is generally better for most types of spinal disease, CT can be helpful in demonstrating bony abnormalities in spine disease.

Brain MRI Scan (Magnetic Resonance Imaging)

A Brain MRI (alternately called a brain scan, MRI scan, or magnetic resonance imaging) is a neurological test which produces a high-resolution image of the contents of the head. It is a commonly used study to evaluate patients with neurological complaints to investigate for diseases of the brain. MRI scans can be performed for other parts of the body as well, including the spine, extremities and chest.

Magnetic resonance imaging, the scientific term behind a brain MRI, is a relatively new technique which uses the quantum mechanical characteristics of protons in your body tissues to create an image. The specific details of the science behind an MRI is quite complex. In general, the patient is placed in a large magnet which aligns all their protons into the same spin. A radiofrequency pulse stimulates these protons, most abundant in water, and an electrical coil around the head detects the signals that result. In the end, the computer uses complex mathematics to convert these signals into an image which the physicians read and interpret.

The appearance of an MRI scanner is similar to a CT Scan in that it is a large donut-shaped tube. The patient's lays on a table while their head is inside the "donut". Unlike a CT scan, no x-rays are used to produce a brain MRI so there is no exposure to radiation. The patient does not feel anything during the performance of the study although some patients complain of claustrophobia while in the scanner.

Sometimes a brain MRI is performed with injection of a contract agent. This is basically a dye that is injected into the blood which shows up brightly on the MRI scan. It can help to make some diagnoses more clearly visible, such as many brain tumors.

What Is It Used For?
As mentioned above, an MRI produces a high-resolution image of the internal parts of the body. There are several different types of MRI imaging which focus on different characteristics of the tissues. By interpreting these various images that are produced, a radiologist or other physicians can help to make diagnoses of medical conditions.

Not all medical conditions have specific findings on MRI. For example, a patient in coma due to uncontrolled diabetes would typically show nothing abnormal in their brain. Rather, brain MRI is good at showing structural changes in or around the brain. For example, MRI is excellent at detecting tumors of the nervous system. They can also show changes in the tissue of the brain consistent with stroke and hemorrhage, or bleeding into the brain.

MRI is more expensive and slower to perform than CT scan, so they are not used for every patient. Pathologies which can be easily diagnosed quickly on a CAT scan, such as acute head trauma and bone pathology, will use that type of brain scan. MRI however is more versatile and shows better resolution of subtle details than a CT scan so it is used frequently for stroke, tumors, spinal disease and other pathology.

Cerebral Angiogram

A cerebral angiogram is a neurological test which evaluates the blood vessels that supply the brain.

Normally, on x-ray the blood vessels are relatively invisible. However, when injected with a radio-opaque dye, the blood vessels show up clearly on an x-ray. This technique is used to visualize the brain blood vessels in a cerebral angiogram but is also used in other parts of the body, such as in a coronary angiogram of the heart.

For a standard angiogram, a small catheter is placed into the blood vessels that supply the brain, the carotid arteries and the vertebral arteries. The catheter is placed through the femoral artery in the thigh and maneuvered up to the head with x-ray guidance. When the catheter is in place, dye is injected into the blood stream while x-rays are taken to allow clear visualization of the blood vessels. X-rays are taken at several time points and from several angles to visualize both the arteries and the venous system in the head.

Some centers now have 3-dimensional angiography machines that rotate around the head while the dye is injected to create a 3D model of the blood vessels. Additionally, some CT scanners have the capability of producing a 3D image of the blood vessels called a CT Angiogram. This has the advantage that no catheter is placed into the artery as the dye can be injected into the general circulation through a standard intravenous catheter (an IV).

In general a cerebral angiogram is safe, but it does have some risks. The catheter in the artery can occasionally cause injury to the artery leading either to bleeding or an arterial dissection and subsequent clotting. This can lead to stroke in rare cases. Additionally, the site of catheter insertion in the leg can be prone to hematoma formation and/or infection. These insertion site complications are generally well tolerated and easily treated in the great majority of patients.

What Is It Used For?
An angiogram is an excellent test to evaluate the blood vessels of the brain and any abnormalities or pathologies that involve them. Common examples of blood vessel abnormalities which can be demonstrated on a cerebral angiogram include cerebral aneurysm, arteriovenous malformation, and Moyamoya disease.

Angiograms are also commonly performed to evaluate blockages of the blood vessels to the brain as in acute stroke or vasospasm.

In addition to being a diagnostic test for these various pathologies and others, some procedures are performed through the catheter while performing an angiogram. These endovascular procedures, usually performed by an interventional neuroradiologist or neurosurgeon, include coiling of aneurysms, embolization of arteriovenous malformations, angioplasty or stenting of obstructed arteries and retrieval of clots during acute stroke. In some types of brain tumors, such as meningiomas, the blood vessels supplying the tumor are embolized prior to surgical removal of the tumor.

Electroencephalogram (EEG)

An electroencephalogram (EEG) is a neurological test which records the electrical activity at the surface of the brain by way of electrodes placed on or in the scalp.

The EEG is performed by placing electrodes on the scalp. Generally, these are superficial stickers which are attached to wires which carry information to the monitor which displays the results. In some cases where a continuous EEG is to be taken for a prolonged period of time, such as in a comatose head trauma victim, the electrodes can be implanted in the scalp as tiny needles.

The electrodes record electrical activity from the surface of the brain which is converted to a trace on the electroencephalogram output, traditionally wiggly lines on a sheet of paper although nowadays they are often simply displayed on a computer screen. The shape, frequency, amplitude and other characteristics of the trace from various regions of the brain are interpreted by a physician, usually a neurologist, and can reveal changes in the electrical activity of the brain.

Evaluation with an EEG varies depending on the clinical situation. In some patients a short EEG will be taken while in others a prolonged EEG overnight or even longer may be required. Patients with epilepsy will often undergo prolonged EEG monitoring in the attempt to catch a seizure on the EEG so that physicians can determine the location it originated from and other characteristics which may help in treatment.

What Is It Used For?
Because the EEG reveals changes in the electrical activity of the neurons in the brain, it can aid in the diagnosis of various pathologies. Traditionally, besides general nervous system research, the EEG has been used to evaluate patients with epilepsy. Seizures, either generalized to the whole brain or focal, can often be seen as a characteristic rhythmic activity on the EEG which is quite different from the normal, seemingly random activity. Therefore, the electroencephalogram is often used to diagnose and work-up patients who present with seizures or activity which is suspicious for epilepsy.

The EEG is also used to evaluate other general changes in the activity of the brain. For example, patients in coma are sometimes followed with EEG both to rule out subclinical seizures but also to evaluate for signs of recovery or brain death. In fact, determination of brain death sometimes utilizes EEG to determine if there is any normal brain activity. While the diagnosis of brain death does not require an EEG, it sometimes helps physicians feel confident that their is no normal brain activity.

Electromyogram (EMG)

An electromyogram (EMG) is a neurological test, usually performed by a neurologist, which evaluates the responses of muscles and the nerves that supply them. It is performed by inserting small needles into various muscles that act as stimulating and recording electrodes. Through these electrodes the muscle is stimulated and the EMG can record the responses that occur in the muscle.

An EMG is often performed along with a nerve conduction study as part of a neurological assessment for various diseases that affect the muscles and/or nervous system.

What Is It Used For?
The EMG provides the physician with information about the functioning of both the muscle and the nerves that supply that muscle. This can be used to help diagnose various diseases that affect these structures. For example, EMG may be used as part of the work-up for diseases of the muscle such as muscular dystrophies. Additionally, along with a nerve conduction study, it may be used to evaluate disease of the peripheral nerves such as peripheral nerve tumors, neuropathies, traumatic nerve injuries, nerve entrapments (such as carpal tunnel syndrome) and various diseases of the spine which involve the nerves as the enter or leave the spinal cord.

Nerve Conduction Study

A nerve conduction study is a neurological test, usually performed by a neurologist and often along with an electromyogram, which evaluates the conduction of electrical impulses down peripheral nerves. Because nerves conduct signals at a standard speed and amplitude, diseases of the nerves which may alter these impulses can be detected by measurement of these signals.

The nerve conduction study is performed by placing surface electrodes over nerves, usually in the arms and/or legs. The electrodes are used to stimulate the nerves and then record the conduction of the signal down the nerve to some other point. This can be done in several positions to help determine the site of nerve injury or disease which may be causing the patient's symptoms.

What Is It Used For?
The nerve conduction test provides physicians with information about the functioning of the peripheral nerves including both the type of dysfunction and the likely location of its cause. This can be used to help diagnose various diseases that impact the nerves. Some pathologies of the peripheral nerves for which work-up can include a nerve conduction test include peripheral nerve tumors, neuropathies, traumatic nerve injuries, nerve entrapments (such as carpal tunnel syndrome) and various diseases of the spine which involve the nerves as the enter or leave the spinal cord.

The information supplied by the test can aid in the diagnosis of these disorders and in some cases can help direct treatment as well. For example, it may direct a surgeon to the likely site of injury of the nerve so that their treatment can be focused on the correct area.