The Neurologic Examination

Figure 33-1. Instruments used to conduct a general neurologic examination.

EVALUATION VERSUS EXAMINATION

The evaluation and the examination of a patient are different but intimately integrated aspects of the patient-physician encounter. In general, the examination is a small umbrella under the larger umbrella of evaluation (Fig. 33-2).

Figure 33-2. Diagrammatic representation of the relationship between the overall evaluation, with its specific components, and the examination in the evaluation of the neurologically compromised patient. CT, computed tomography; MRI, magnetic resonance imaging.

Evaluation covers all the aspects related to a specific medical event (Fig. 33-2). It includes the current complaint, which is the main reason that the patient seeks medical attention at that time, and the history of present illness, which focuses on the details and circumstances surrounding the main complaint, such as time course (abrupt onset as opposed to slowly progressive), associated symptoms (pain, blurred vision, headache, inability to talk, and so on), and predisposing or concurrent factors (with exercise or physical activity, warm weather, or exposure to drugs). Remember that it is essential to obtain information from an observer, such as a family member or friend, to characterize many neurologic conditions (such as seizures, dementia, and loss of consciousness) when the patient may not be aware of the events. The past medical and surgical histories focus on learning facts about past illnesses; concurrent medical problems, such as arterial hypertension, diabetes mellitus, or history of cancer, may be pertinent to the new medical complaint. Surgical procedures that the patient may have had in the past are also important clues in the medical history. Family history is an essential part of the medical history and may explain the present medical issue. For example, some forms of hand tremors or strokes at an early age may be genetically determined. Social history inquires about the patient’s habits such as smoking, alcohol or illicit drug abuse, life style, and occupation. Medications that the patient is taking are also detailed in the history. Review of systems is a systematic general review of all systems, including cardiovascular, respiratory, genitourinary, and gastrointestinal.

Physical examination, or simply examination, is an important part of the more extensive evaluation of the patient (Fig. 33-2). In general, it includes the patient’s vital signs and a general examination by systems with a more focused examination of the system involved in the current medical problem. For example, if the patient complains of acute onset of chest pain and shortness of breath, a detailed cardiovascular examination is in order with a general examination of the abdomen and a brief neurologic examination. On the other hand, if a patient has sudden onset of weakness of the right side of the body and difficulty speaking, a detailed neurologic examination is called for.

Diagnostic studies (Fig. 33-2) may be ordered as a result of the overall evaluation of the patient to confirm a possible diagnostic hypothesis. For example, chemical, cytologic, and bacteriologic examination of cerebrospinal fluid can be done to confirm suspected meningitis, or computed tomography or magnetic resonance imaging of the brain can be ordered to confirm the localization of a stroke and to determine whether it is ischemic or hemorrhagic.

Finally, the impression (Fig. 33-2) of the evaluating physician of what and where the problem might be with recommendations on management and therapy indicated simply puts together the overall evaluation by the examiner and sets the immediate course of treatment and future health care plans for the patient.

MENTAL STATUS EXAMINATION

The mental status examination starts first with an assessment of the level of consciousness of the patient. Orientation to time, place, and person should also be documented. Memory of past events and short-term memory as well as the ability to calculate are also evaluated at this time. This basic examination is known as the Folstein Mini-Mental Status test (Fig. 33-3). Special tests of parietal lobe function include drawing a clock face (Fig. 33-4), bisecting a line, and copying a picture of a daisy or drawing a set of intersecting pentagons.

Figure 33-3. The Folstein Mini-Mental Status examination.

Figure 33-4. A clock face drawn by a patient with a parietal lobe lesion.

Speech disorders such as dysarthria are detectable in ordinary conversation and result from defects of articulation of the words secondary to tongue (cranial nerve XII), palate (cranial nerves IX and X), lips (cranial nerve VII), or pharyngeal muscle weakness or incoordination. Evidence of a speech disorder is usually pursued by asking the patient to repeat a difficult phrase like “Methodist Episcopal” or to repeat the sounds “puh-tuh-kuh” rapidly.

Language is the ability to use and to understand written and spoken speech and is a function of the cortical, thalamic, and basal nuclei language circuits located in the dominant cerebral hemisphere. Language is assessed by asking the patient to repeat words or phrases (“no ifs, ands, or buts”), to name simple objects (watch, finger, pen), to follow commands (touch your left shoulder, close your eyes, point to the ceiling), and to write a sentence and read it aloud.

Language abnormalities are called aphasias. There are two major types: nonfluent aphasia and fluent aphasia. In nonfluent aphasia, the patient has difficulty with verbal self-expression, producing the words only with great effort, but is able to understand and to follow commands appropriately. Nonfluent aphasia is also called an expressive or Broca aphasia; a lesion resulting in this type of deficit is found in the inferior frontal gyrus (sometimes called the Broca convolution) specifically involving the pars opercularis and the pars triangularis. In fluent aphasia, the patient has normal or even increased production of words, sometimes in long sentences with normal prosody (rhythm of speech); well-articulated but frequent neologisms (a series of meaningless words) give these sentences no content or meaning. In fluent aphasia, also called a receptive or Wernicke aphasia, neither the patient nor the examiner is able to understand the meaning of the patient’s speech. A lesion of the lateral aspect of the dominant hemisphere in the area of the supramarginal and angular gyri (and sometimes adjacent portions of the superior temporal lobe) may result in fluent aphasia.

CRANIAL NERVE FUNCTION TESTING

Cranial Nerve I

The olfactory nerve (cranial nerve I) is rarely tested because of the deleterious effects of smoking and sinus disease on the sense of smell in the general population. The nerve can be unilaterally damaged by trauma or a tumor of the skull base in the olfactory groove, such as an olfactory groove meningioma (see Fig. 7-9). Total loss of the ability to smell (anosmia) is always associated with the inability to taste food (ageusia) as well, a familiar example being the unappealing taste of food associated with the nasal congestion of a head cold. Dysgeusia is an unappealing or altered sense of taste, and parosmia is an altered or perverted perception of odors.

An olfactory stimulus should be nontrigeminal, that is, it should not tickle or irritate the inside of the nose (as does ammonia, for example), which is innervated by the trigeminal nerve. Commonly used substances are vanilla, coffee, and perfumed soap. With the patient’s eyes closed, occlude one nostril and bring a vial of the substance near the open nostril (Fig. 33-5). Ask the patient whether he or she smells something. The sensing of odor is more important than its identification. The process is then repeated for the other nostril.

Figure 33-5. Testing of the sense of smell (olfaction). The patient presses one nostril closed, and the open nostril is exposed to an aromatic substance.

Cranial Nerve II

The optic nerve (cranial nerve II) is tested by measurement of visual acuity (a measurement of the ability to detect fine detail and contrast in an image) and assessment of the extent of peripheral vision by examination of visual fields and by inspection of the retina and the optic nerve head with the ophthalmoscope. Visual acuity (also called visual resolution) is tested separately for each eye and should be recorded with use of the patient’s best spectacle correction and a hand-held visual acuity chart or a Snellen chart at 20 feet (Fig. 33-6). The number beside each line of letters indicates the number of feet at which the letters can be read by a person who has normal vision; thus, normally, the letters in the line designated 20 can be read at 20 feet, and the visual acuity is recorded as 20/20.

Figure 33-6. The hand-held visual acuity chart.

Examination of the visual fields is an important part of the ophthalmologic and neurologic examination. This procedure provides information about the entire visual pathway from the optic nerve to the occipital cortex. Because lesions interrupting various parts of the pathway cause specific types of defects in the visual field, it is frequently possible to determine the location of the lesion (see Chapter 20 for examples). There are several different methods for evaluation of the visual field. The most common method used by most neurologists at the bedside is the confrontation visual field examination. The examiner faces the patient being examined. The patient should cover one eye with the palm of the hand or with an eye occluder and fixate the gaze of the eye to be examined on the examiner’s nose. The examiner then presents a stimulus in each of the four quadrants—upper and lower nasal and upper and lower temporal—of the visual field; finger movement, rapid finger counting, or hand comparison may be used for this purpose (Fig. 33-7).

Figure 33-7. Visual field examination by confrontation. One eye is covered (A), and all visual quadrants are tested for that eye. The procedure is repeated for the other eye (B).

Lesions of the various structures collectively making up the visual pathway give rise to deficits that are characteristic of the specific portion of the pathway compromised. These lesions and corresponding deficits are considered in detail in Chapter 20 and are only summarized here (Fig. 33-8). A scotoma (Greek for “spot”) is a defect of the visual field surrounded by normal vision. A scotoma is most frequently the result of a lesion within the retina or the optic nerve but may also be seen in cases of stroke or tumor along the course of the visual pathway. It is perceived as an area within the field of vision where the patient cannot see. The blind spot is a physiologic scotoma that represents the position of the optic disc within the visual field (the optic disc has no rods, cones, or ganglion cells; see Chapter 20).

Figure 33-8. Representative visual field deficits as correlated with the name of the deficit and the location of the lesion. Also consult Chapter 20 for more information on the visual system.

Lesions of the visual pathway result in characteristic visual deficits. There are many variations to this theme, and only a few examples are illustrated in Figure 33-8 (for more detail on the visual system, consult Chapter 20). For example, loss of vision in half of the field in one eye is called hemianopia, and loss of vision in corresponding halves of the visual fields of both eyes is called right or left homonymous hemianopia, depending on which visual fields are lost. Loss of vision in the temporal halves of the visual fields of both eyes is called bitemporal hemianopia. The loss of a quadrant of the visual field, a homonymous quadrantanopia, is most commonly seen in lesions involving the white matter between the lateral geniculate body and the visual cortex, which is located on the superior and inferior banks of the calcarine sulcus in the occipital cortex.

The retinotopic organization is well preserved throughout the visual pathway. A careful examination of visual field deficits may be instrumental in precise localization of these lesions (Fig. 33-8).

The appearance of the optic nerve head or the optic disc is examined with an ophthalmoscope (Fig. 33-9) while the patient looks at a distant object. To examine the patient’s right eye, the examiner holds the ophthalmoscope with the right hand and uses his or her own right eye; this technique is reversed for examination of the patient’s left eye. With the ophthalmoscope dial set on zero, the pupillary red reflex (the point at which the red retinal reflex is seen “glowing” in the pupil) is located from a distance of 2 or 3 feet (Fig. 33-9A). The examiner slowly approaches the patient’s eye as if viewing the eye through a keyhole. At the same time, plus or minus lenses, as needed, are dialed on the ophthalmoscope to focus on the patient’s retina. The optic disc is located by directing the ophthalmoscope slightly toward the nasal side of the patient’s retina (Fig. 33-9B). The appearance of the optic disc is important. It is normally round or slightly oval and of a yellow-red color, with clearly defined margins (Fig. 33-10A). Veins are darker and slightly larger in diameter than arterioles. The presence of the central cup, or excavation, and its size should be documented (Fig. 33-10B).

Figure 33-9. Ophthalmoscopic examination. The examiner locates the red reflex (A) and then focuses on the details of the optic nerve (B) through the pupil.

Figure 33-10. Normal optic disc (A) and an example of an abnormally enlarged central cup (B) in a patient with glaucoma.

Papilledema, or swelling of the optic disc, is usually due to increased intracranial pressure, regardless of the cause of the pressure increase. Early signs of papilledema include disappearance of the normal cup, blurring of the disc margins, and arching and elevation of the vessels as they pass over the margin of the disc. As papilledema progresses, exudates and hemorrhages as well as tortuosity of the vessels appear (Fig. 33-11).