The Neurologic Examination: Sensory System
Introduction
Cranial Nerves
Motor Exam
Inspection and Palpation
Reflexes
Gait
Sensory System
Reading List
Introduction
The basic neurologic examination includes six primary components -- examinations of the patient's:
Mental status
Cranial nerves
Coordination
Sensation
Motor system
Gait
When performing a neurologic examination on a patient with a movement disorder or who is suspected to have a movement disorder, the primary findings will, obviously, be apparent when examining the
motor system. However, many other aspects of the neurologic exam may be abnormal as well. This review is intended to highlight the basic examination with an emphasis on those areas that are of
particular interest, as they pertain to patients with movement disorders or who are suspected to have a movement disorder.
Mental Status
When conducting an assessment of mental status, it is important to keep in mind that many factors may have an impact on the results of the patient's exam. Some factors include the time of day
during which the exam is conducted; the patient's levels of stress, fatigue, pain, and education; and the patient's socioeconomic status. The mental status exam includes ascertainment of the levels
of consciousness (i.e., normal, depressed, or hyper-alert), attention, and cooperation. A brief assessment of cognitive functioning identifies deficiencies in orientation, the patient's fund of
knowledge, memory, insight and judgment, concentration, ability to perform calculations, abstract thought, and verbal fluency.
Generalized impaired attention and cooperation are nonspecific findings and not likely to be related to a movement disorder. If difficulties in language and calculations are present, identifying these may help to specify the location of any underlying lesions. Movement disorders in which cognitive impairment is a prominent finding include:
Lewy body disease
Corticobasal degeneration
Late-stage Parkinson's disease
Huntington disease
A very small percentage of patients with late-stage Wilson's disease may show evidence of cognitive impairment as well.
Key point/callout: Pain, stress, low levels of education, and the cognitive impairment that may manifest during late-stage Parkinson's disease may all inhibit a patient's ability
to attend to and process new information and recall previously stored information.
Cranial Nerves
Careful assessment of cranial nerves can assist the clinician in identifying specific neurologic lesions or deficits that are related to movement disorders. Assessing olfaction (cranial nerve I) is particularly important in differentiating Parkinson's disease from other parkinsonian syndromes. In Parkinson's disease, pupillary reflex imbalance (cranial nerves II and III) may occur, primarily through involvement of the parasympathetic system.
Disorders of eye movements usually manifest as instability of visual gaze (nystagmus -- periodic, rhythmic ocular oscillation involving vertical, horizontal, and/or torsion movements) or jerkiness of pursuits (eye tracking) or saccades (visual scanning) (cranial nerves III-V). Periodic nystagmus is often found in patients with spinocerebellar degeneration, and pendular nystagmus in those with brain stem or cerebellar degeneration, including patients with Parkinson's disease.
By definition, opsoclonus-myoclonus involves irregular, rapid eye movements. Abnormalities in eye movements are also often seen early in the course of Huntington disease. These abnormalities are primarily related to saccades, as evidenced by slow initiation, lack of coordination, intrusion into and disruption of smooth pursuit, and lack of inhibition in response to a peripheral stimulus when attempting to look in the opposite direction.
The hallmark of progressive supranuclear palsy (PSP) is a down-gaze palsy in which the patient is unable to look down on command even though, when the examiner lifts the patient's head, the patient is able to track downward. Other difficulties with eye movements that are common in patients with PSP include impaired saccades, slow visual pursuit, unstable fixation, and disturbed convergence. Manifesting as blurred vision, double vision, or reading difficulty, these visual impairments may worsen the gait and balance problems found in patients with progressive supranuclear palsy. (See video examples of disordered eye movements)
Several forms of dystonia may have abnormal findings on examination of the cranial nerves.
Blepharospasm is posited to involve abnormal plasticity of the neuronal circuits mediating blink reflexes (V and VII). Dysfunction of cerebellar afferent pathways may underlie the pathophysiology of cervical dystonia, with potential involvement of the 11th cranial nerve.
Hemifacial spasm, a form of segmental myoclonus, is characterized by involuntary, paroxysmal, tonic, or clonic contractions of the muscles innervated by the seventh cranial nerve. Cranial nerves V, VII, IX, X, and XII are involved in the articulation of speech. Abnormalities in one or more of these nerves may be manifest in spasmodic dysphonia and the hypophonia of Parkinson's disease.
Key point/callout: Nystagmus is an eye movement disorder that manifests as an instability of visual gaze with periodic, rhythmic ocular oscillation involving vertical, horizontal, or torsion movements or a combination thereof.
Key point/callout: Abnormalities of eye movement are common in patients with Huntington disease, with an increase in saccade latency and a higher variability in saccade latency.
Motor Exam
Examination of the motor system involves observation, palpation, and assessment of tone, function, and strength. The first step in the examination of the motor system is to simply observe the patient.
Observation
Abnormal Movements
If spontaneous, abnormal, adventitious movements -- not an abnormality of normal movements -- are found, they should be characterized according to type, age of the patient at onset, mode of onset, and clinical course of the movements. Abnormal hyperkinetic movements include tremor, tics, dystonia, chorea, ballismus, myoclonus, and athetosis, all of which usually decrease in intensity and frequency or disappear during sleep. Factors related to the temporal onset of hyperkinetic movements and recent institution of dietary, pharmacologic, or homeopathic remedies, including recent or long-term exposure to toxins, should be noted. Time of day when the movements occur most commonly must be also be identified.
Tremor
Tremor, an involuntary, rhythmic oscillatory movement of one or more parts of the body, results from alternating or irregularly synchronous contractions of antagonist muscles. Tremor can be differentiated according to:
- The involved body part
- Provocative and palliative factors
- Frequency (i.e., fast versus slow) of the movement
- Amplitude (i.e., coarse versus fine) of the movement
When assessing tremor, it may be helpful to observe patients with their hands resting in their laps and while writing or drinking, to have them draw (such as an Archimedean spiral), and to perform the finger-nose-finger test.
Tremor type. The subsequent exam should further delineate the tremor type. An action tremor is usually exhibited when the body part is moved from one point to another (kinetic tremor), with muscle contraction against a fixed object (isometric tremor), and or when writing or performing other specific activities (task-specific tremor). The typical frequency of an action tremor is between 3 and 10 Hz.
A postural tremor is exhibited when the position of the body part is maintained against gravity. To elicit this type of tremor, the clinician can simply ask the patient to extend his or her arm or leg, as indicated, and hold it in that position for a period of time. Essential tremor, the most common type of postural tremor, has a moderate to high frequency and low amplitude.
A rest tremor, by definition, is exhibited while the affected body part is at rest. The tremor is typically worse during mental distraction, i.e., during the cognitive assessment while the patient is counting by 7's. A rest tremor decreases with intentional movement, has a low to moderate frequency (i.e., 3-6 Hz), and has a high amplitude. The tremor of Parkinson's disease is an example of a rest tremor, although this may also be a mixed tremor, and 20% of patients with Parkinson's disease have no tremor at the onset of disease.
Tics
Because these unvoluntary (as opposed to involuntary in that the movements can often be suppressed, albeit with a resultant increased level of patient discomfort), compulsive, repetitive, stereotyped movements may not always be readily apparent or observable during the neurologic examination, obtaining a valid history or reviewing videotape of the tics may be necessary. Tics may be motor or vocal, or a patient may have both motor and vocal tics. The tics should be classified as simple or complex.
Simple motor tics are typically abrupt, brief, repetitive isolated movements, such as eye blinking or facial twitching, neck stretching, head jerking, or shoulder shrugging.
Complex motor tics involve several muscle groups and may be manifest as repetitive squatting, skipping, hopping, or even more complex movements (see the table below).
| Manifestation of Complex Motor Tics |
|---|
| Touching of others |
| Deep knee bending |
| Jumping |
| Smelling of objects |
| Hand gesturing |
| Head shaking |
| Leg kicking |
| Turning in a circle |
Simple vocal tics include grunting, throat clearing, sighing, barking, hissing, sniffing, tongue clicking, or snorting, with complex vocal tics involving phrases or words.
During the examination, other factors should be elicited related to the tics, including the frequency of occurrence and suppressibility of the tics, as well as any provocative factors related to the tics.
Dystonia
Dystonia is characterized by sustained muscle contractions that frequently cause twisting or repetitive movements and abnormal, sometimes painful, postures or positions. Dystonia may affect any part of the body, including the arms, legs, trunk, neck, head, or face. The examiner should note the involved body part or parts, provocative factors, and sensory "tricks" that the patient may employ to suppress the movement.
Key point: dystonia: is a neurologic movement disorder characterized by sustained muscle contractions, usually producing twisting and repetitive movements or abnormal postures or positions. Almost all dystonic movements share a directional quality that is typically sustained, sometimes for an instant, as well as a consistency and predictability. Dystonic movements are directional, forcing the involved body part or region into an abnormal position, which is consistently present.
Chorea
The involuntary, rapid, irregular, jerky movements of chorea may affect one or more parts of the body, including the face, arms, legs, or trunk. The two most commonly encountered disorders with choreiform movements as a primary component are Huntington disease and Sydenham chorea. The examination should include delineation of the involved body part.
Athetosis. The involuntary, relatively slow, writhing movements of athetosis are often found in combination with other abnormal movements, such as chorea. The examination should include notation of affected body parts, which typically include the face, neck, tongue, and hands, but may affect any muscle group.
Choreiform movements.
- Are a common finding in Huntington disease, Sydenham chorea, and multiple system atrophy
- Are involuntary, rapid, regular, jerky movements
- May affect the face, arms, legs, or trunk, or a combination these body parts
- Are violent flinging movements
Ballismus
Ballismus, also known as ballism, is a violent flinging movement of a limb or limbs. The examination should include delineation of the involved body part, whether the movements occur on a continuous or intermittent basis, and whether the movements are restricted to one side of the body (hemiballism) or occur on both sides. These movements are not typically isolated findings; instead, patients most likely have a variety of movements, including ballismus, chorea, athetosis, and dystonia. Note should be made of any other associated movements.
Myoclonus
The movements of myoclonus consist of sudden, brief, shock-like movements. Positive myoclonus results in contraction of a muscle or multiple muscles. Asterixis, or negative myoclonus, occurs with brief momentary loss of agonist muscle tone and subsequent contraction of antagonist muscles. These nonsuppressible movements often have a characteristic saw-tooth pattern. During the examination, note should be made of the affected body part and the amplitude and persistence of the movements. Spontaneity of movements and provocative factors should be elicited during the exam. Movements may be provoked by having patients sit with their arms outstretched or by flicking the patients' distal finger joints and observing any responsive movement. The examiner may also clap her or his hands and note the patients' response. The examiner should note whether the movements are induced via action or whether a flapping motion, indicative of asterixis, is present. In addition, a movement score can be calculated by measuring the number of jerks over a set period of time, e.g., 60 to 120 seconds.
Inspection and Palpation
Most patients with movement disorders do not experience muscle wasting or hypertrophy. The exceptions to this are patients with dystonia, who may develop hypertrophy related to their disease, and disuse atrophy, which may occur in weakened muscles associated with spasticity. Fasciculations, which are involuntary contractions of the muscle fibers innervated by a motor unit, can be visualized as muscle twitches or dimpling under the skin. These fine quivering movements occur more commonly in patients with lower motor neuron disease and not those with movement disorders. Muscle tenderness (myositis) is not typically a finding when assessing the patient with a movement disorder.
Assessing Tone
To properly assess tone (i.e., the baseline amount of muscle resistance to passive movement about a joint), the clinician must move each of the patient's limbs through its full range of motion at two or more joints. Abnormalities of tone that may be encountered include hypotonia, or too little tone, and hypertonicity, an elevated amount of tone. In its extreme state, hypotonicity is referred to as flaccidity.
When hypertonicity is encountered, the next step in the assessment is to determine whether the increased tone is spasticity (which is defined as a velocity-dependent increase in stretch reflexes that results from an upper motor neuron lesion) or rigidity (which results from a lesion or process occurring in the basal ganglia). The difference between the two is in their relationship to directionality and velocity. With rigidity, the examiner feels the increased resistance during flexion and extension. With spasticity, the resistance is more unidirectional -- i.e., only with flexion or extension, but typically not both. With rigidity, the examiner appreciates the difference in increased resistance at all speeds of movement; with spasticity, the examiner detects the resistance at higher velocities -- i.e., the faster the joint is moved, the more resistance that the examiner feels. The point at which the examiner encounters resistance in spasticity is known as the spastic catch. Conversely, when the examiner is encountering resistance while moving a spastic limb through its range of motion, in some patients she or he will reach a point at which the resistance "gives way" -- this is called the clasped knife phenomenon.
Although rigidity is a common finding on examination, patients with Parkinson's disease do not typically report having rigidity per se; instead they may express that they are having stiffness in their shoulders or other muscles or arthritis-like symptoms. Cogwheel rigidity is a particular type of rigidity that is frequently found in patients with Parkinson's disease. When the affected arm is moved through its range of motion at the elbow, the examiner will encounter a ratcheting type sensation, particularly when palpating the biceps tendon. To elicit cogwheel rigidity, it may be necessary for the examiner to ask the patient to mirror the movements that the examiner is performing, i.e., to move his or her arm in the same manner in which the examiner is passively moving the opposite arm.
Assessing Function
When assessing function, it may be necessary to ask the patients to perform the activity -- such as finger, hand, or foot tapping or alternating pronation and supination of the hand -- for some period of time. Characteristic of parkinsonian syndromes is a difficulty with initiating movement. Once initiated, the movements of patients with Parkinson's disease are fairly rhythmic, however, as opposed to those of patients with cerebellar disorder, which have an irregular rhythm. The movements of Parkinson's disease tend to be relatively slow and of a decreased amplitude. Another distinguishing feature, and the purpose of observing the patient for some time, is that patients with Parkinson's disease often have a slowing of movements with repeated performance of the task, whereas patients with cerebellar disorders can typically sustain the speed of movements ad infinitum. Poor accuracy in the movements is characteristic of cerebellar disorders. Patients with Parkinson's disease or other parkinsonian disorders may be unable to perform rapidly alternating pronation and supination as the result of akinesia or rigidity.
Assessing Strength
To detect asymmetry in strength, each muscle group should be tested along with its contralateral counterpart. A 6-point scale, such as the one included below, can be used to rate muscle strength. With the exception of patients who have spasticity, strength should be normal in most if not all movement disorders; in addition, patients with chorea may have what is known as a milkmaid's grip in which there is a fluctuation in grip strength.
| Score | Finding |
|---|---|
| 5 | Normal strength |
| 4* | Some resistance but movement is possible |
| 3 | Movement is possible against gravity but not against resistance by examiner |
| 2 | Movement possible, but not against gravity |
| 1 | Muscle flicker but no movement |
| 0 | No muscle contraction |
*often subdivided as -4, 4, +4
The examiner should also check for drift, which may be indicative of an upper motor neuron lesion (e.g., trauma, MS, stroke). When patients with an upper motor neuron lesion are asked to extend their arms, suppinate their hands, and hold them parallel to the floor, they may have a subtle turning in and downward drift.
Assessing Posture
Posture is typically assessed by having the patient stand, while the examiner looks for sway or instability. Any movement disorder that is the result of a cerebellar dysfunction will result in ataxia, a swaying unstable posture. Postural instability is a common finding in Parkinson's disease and in other atypical parkinsonian syndromes, such as PSP. The examiner can test for instability by standing behind the patient and asking the patient to maintain her or his balance. The examiner then attempts to briskly pull the patient back while being careful to prevent the patient from falling. Note should be made of the results of this pull test, i.e., the patients ability to recover from being pulled backward. The examiner should also ask the patient to stand with his or her eyes closed, and note should be make of any ataxia.
Reflexes
The next step in the examination of the neurologic system is an assessment of reflexes in all four limbs, noting both the strength of the reflex as well as the symmetry. Abnormal reflexes may be manifest as the result of derangements in electrolyte levels or thyroid functioning or in patients who are anxious; reflexes also tend to decrease with advancing age. Deep tendon reflexes are rated as per the table below and are considered normal if they are symmetrical and rated between 1+ and 3+. Asymmetrical reflexes or a substantial difference in reflexes between the upper and lower limbs are indicative of the need for further study.
| Score | Finding |
|---|---|
| 0 | Absent reflex |
| 1+ | Trace, or seen only with reinforcement |
| 2+ | Normal |
| 3+ | Brisk |
| 4+ | Nonsustained clonus |
| 5+ | Sustained clonus |
The presence of clonus, a series of sustained rhythmic jerks following quick stretch of a muscle, usually indicates an upper motor neuron abnormality. Attempts should be made to elicit clonus whenever hyperreflexia is encountered. To test for clonus, the examiner should hold the patient's foot and lower leg in a relaxed position and quickly dorsiflex the ankle. While maintaining the leg in a dorsiflexed position, the examiner will feel the rapid oscillation of the flexion and extension of the foot when clonus is present.
Gait abnormalities are a common finding in patients with movement disorders. The first stage in assessing the gait disturbances is to simply observe the patient. The examiner should watch closely as the patient is seated in a chair and then rises to a standing position. Patients with Parkinson's disease or other movement disorders that cause a loss of strength in the lower limbs will often need to use more upper body muscles to rise from a chair, as opposed to relying on their leg strength to stand. Note should be made of the patient's standing posture; approximately 75% of patients with Parkinson's disease will lean forward from the waist, resulting in instability.
The examiner should then observe the patient walking across the room or down the hall, noting the stride length, positioning of the feet, degree of arm swing, presence of abnormal movements, momentum, and ability to turn smoothly. Patients should be asked to walk in a heel-to-toe fashion along a line (tandem gait), to walk on their toes, and to walk on their heels.
Gait difficulties are a common finding in Parkinson's disease, but are typically not one of the early manifestations of the disease. These difficulties with ambulation include postural instability, as well as a freezing gait, diminished or absent arm swing, festination, and hesitancy with initiation of movement. When patients with Parkinson's disease have a freezing episode, they literally become rooted in place, feeling as if their feet are stuck to the floor. Freezing often occurs when patients attempt to walk through a doorway or turn around. The forward-flexed posture of Parkinson's disease combined with a festinating (accelerating) gait leads to the typical propulsive gait in which patients take small, rapidly accelerating, shuffling steps with their weight on the ball of the foot. Leaning forward may be a manifestation of the patient's difficulty with initiating movements, such that the patient leans further and further forward in an attempt to begin walking. (See video example of gait in Parkinson's disease.)
The parkinsonian gait should be distinguished from the apraxic gait, which results from bilateral dysfunction in the frontal lobes. Patients with an apraxic gait also have a stooped posture and short shuffling steps. Their difficulties in initiating and maintaining walking are the result of deficits in executive functioning. When asked to walk, patients with an apraxic gait appear to forget how to initiate the movement and often stop walking for no apparent reason. The examiner should also discriminate between the parkinsonian gait and that of patients with normal pressure hydrocephalus, which is a broad-based gait that also may include the parkinsonian-like features of hesitancy of initiation of movement and freezing but more closely resembles an apraxic gait.
Patients with Huntington disease and other forms of chorea typically have intermittent, involuntary, irregular jerky movements and slow writhing movements of both upper and lower extremities that interrupt the normal flow of walking; this is known as a choreoathetotic gait. Additional movements tend to be lurching in quality as the result of unpredictable flexion and extensions at the hip.
Patients with spasticity of the lower limbs may exhibit one of a variety of abnormal gaits. A steppage gait, also known as a foot-drop gait, is one in which the toes hang down and drag on the floor while the patient is walking. Spasticity may also cause a scissoring gait, in which the legs are flexed slightly at the hips and knees, such that the patient appears to be crouching, with the knees and thighs hitting or crossing in a scissors-like movement. A typical hemiparetic gait involves a fisting of the hand with the arm held in a flexed position and a circumduction of the leg.
Patients with cerebellar ataxia walk with a broad-based gait with irregular stride lengths and speeds. Those with a sensory ataxic gait have a similar gait but also have a positive Romberg sign when tested with their eyes closed.
Sensory System
Assessment of the sensory system, i.e., light touch, vibration, and joint-position sense (proprioception) are typically normal in patients with movement disorders. One exception, however, is restless legs syndrome, in which abnormalities have been identified in central somatosensory processing, including static mechanical hyperalgesia.
