A neurological examination
is the assessment of sensory neuron
responses, especially reflexes
, to determine whether the nervous system
is impaired. It can be used both as a screening tool and as an investigative tool, the former of which when examining the patient when there is no expected neurological deficit and the latter of which when examining a patient where you do expect to find abnormalities. If a problem is found either in an investigative or screening process then further tests can be carried out to focus on a particular aspect of the nervous system (such as lumbar punctures
and blood tests
Generally a neurological examination is focused towards finding out if there are lesions in the central nervous system and peripheral nervous systems or whether there is another diffuse process which is troubling the patient. Once the patient has been thoroughly tested, it is then the role of the physician to determine whether or not these findings combine to form a recognizable medical syndrome such as Parkinson's disease or motor neurone disease. Finally, it is the role of the physician to find the etiological reasons for why such a problem has occurred, for example finding if the problem was due to inflammation or congenital.
A patient's history is the most important part of a neurological examination and must be performed before any other procedures unless impossible (i.e. the patient is unconscious). Certain aspects of a patients history will become more important depending upon the complaint issued. Important factors to be taken in the medical history include:
- *Time of onset, duration and associated symptoms (e.g. is the complaint chronic or acute)
- *Age, sex and occupation of the patient
- *Handedness (right or left handed)
- *Past medical history
- *Drug history
- *Family and social history
Handedness is important in establishing the area of the brain important for language (as almost all right-handed people have a left hemisphere which is responsible for language). As patients answer questions, it is important to gain an idea of the complaint thoroughly and understand its time course. Understanding the patient's neurological state at the time of questioning is important, and an idea should be obtained of how competent the patient is with various tasks and their level of impairment in carrying out these tasks. The interval of a complaint is important as it can help aid the diagnosis. For example, vascular disorders occur very frequently over minutes and hours, whereas congenital disorders occur over a matter of years.
Carrying out a 'general' examination is just as important as the neurological exam as it may lead to clues to the etiology of the complaint. This is shown by cases of cerebral metastases where the initial complaint was of a mass in the breast.
Central nervous system
The central nervous system (CNS) consists of the brain
and the spinal cord
and is responsible for the integration of all nervous activity. Examination of the CNS involves:
- * The assessment of consciousness, often using the Glasgow Coma Scale (EMV)
- * Mental status examination, often including the abbreviated mental test score (AMTS) or mini mental state examination (MMSE)
- * Global assessment of higher functions
- * Intracranial pressure is roughly estimated by fundoscopy; this also enables assessment for microvascular disease.
Peripheral nervous system
Each individual peripheral nerve has its own indivudual test(s). Peripheral nerves are responsible for and can be tested by the following:
- * Cranial nerves (I-XII): sense of smell (I), visual fields and acuity (II), eye movements (III, IV, VI) and pupils (III, sympathetic and parasympathetic), sensory function of face (V), strength of facial (VII) and shoulder girdle muscles (XI), hearing (VII, VIII), taste (VII, IX, X), pharyngeal movement and reflex (IX), tongue movements (XII). These are tested by their individual purposes (e.g. the visual acuity can be tested by a Snellen chart).
- * Reflexes: masseter, biceps and triceps tendon, knee tendon, ankle jerk and plantar (i.e. Babinski sign). Globally, brisk reflexes suggest an abnormality of the UMN or pyramidal tract, while decreased reflexes suggest abnormality in the anterior horn, LMN, peripheral nerve or motor end plate. A reflex hammer is used for this testing.
- * Muscle strength, often graded on the MRC scale 1 to 5 (or I to V).
- * Sensory systems are rarely tested but they control the sensations of fine touch, pain and temperature.
- * Muscle tone and signs of rigidity.
Specific tests in a neurological examination include:
The results of the examination are taken together to anatomically identify the lesion
. This may be diffuse (e.g. neuromuscular diseases, encephalopathy) or highly specific (e.g. abnormal sensation in one dermatome
due to compression of a specific spinal nerve by a tumor deposit). A differential diagnosis
may then be constructed that takes into account the patient's background (e.g. previous cancer, autoimmune diathesis) and present findings to include the most likely causes. Examinations are aimed at ruling out the most clinically significant causes (even if relatively rare, e.g. brain tumor in a patient with subtle word finding abnormalities but no increased intracranial pressure
) and ruling in
the most likely causes.