Clinical Examination: Utilization and Imitation Behaviors (Video Segment 2 on Companion DVD)
The classic signs of frontal syndrome are usually well known. Distractibility and attentional disturbances are easy to detect when several people are present in addition to the patient and the examiner. Therefore, it is very important that all of them remain completely neutral and indifferent toward the patient, and do not react during the clinical examination.
As described by Lhermitte "the test begins with the solicitation of manual grasping behavior." The examiner places his or her hands on the patient's palms and stimulates them with slow and rapid rubbing movements. A bilateral grasping reflex is obtained, even if the patient is instructed not to take the hands of the examiner. Moreover, the patient holds the hands so tightly that the examiner can lift the patient from the chair.
Then, while the hands of the patient are free, the examiner displays various objects in the field of vision of the patient. The patient may grasp the object and collect as many objects as he or she can hold (collectionism). Moreover, he or she usually starts to use them in a proper manner (utilization behavior) (6). When the patients are asked why they took them and used them, the answer is "because I thought I had to take them and use them." Normal subjects do not react this way.
Moreover, even when the examiner tells the patient "whatever I do, do not imitate me," the patient will still do it, all the same. The patient may copy funny behaviors, with or without actual objects (imitation behavior) (7). When asked why they imitated the examiner, they answer, "Because I thought I had to imitate." Again, a normal subject never imitates the examiner (except to make fun of him!).
These tests are very sensitive, easy to do at the bedside and take only a few minutes. EYE MOVEMENTS
Bedside Examination (Video Segments 3 and 4)
The patient may complain of problems with visual acuity as they cannot read properly anymore. Several pairs of glasses have been changed unsuccessfully. The upward- and downward-gaze impairment are rarely detected by the patient. In contrast, the family will observe "a reptilian" gaze, with a staring and terrified look.
The bedside examination will mainly explore the visually guided saccades in four directions (up, down, left, and right). The targets should be at a certain distance (arm length). The best way to have the right distance and to prevent movements of the head is to hold the chin of the patient at arm length. The targets should be clearly visible (colorful balls or pens). The midline target should be neutral (e.g., the switch of the light) and the lateral should be 25° from the midline target. Voluntary saccades are made after verbal instruction: "look at the switch," "look at the red pencil." Note the time taken to initiate the saccade, its speed, and its amplitude (the target is reached with the initial saccade or correction with additional small saccades are needed). In normal subjects, the displacement of the eyes cannot be detected by the examiner (who sees the initial and the final positions of the eyes). Any perception of the displacement (like in oil) is abnormal. People usually focus on vertical gaze (because of the diagnostic criteria of PSP). However, horizontal saccades are impaired at a early stage of the disease and bedside examination can also detect this abnormality.
In summary, as Drs. Leigh and Riley stated, "it is saccadic speed that counts and the key finding is slowing of the saccade" (8). This can be observed before reduced amplitude is detected.
Testing visual pursuit is not very useful as pursuit is frequently altered (including by drugs). Moreover, testing pursuit is testing the velocity of the target, more than those of the eyes.
Vestibular ocular reflexes (VORs) are normal in PSP patients, by definition (supranuclear palsy).
In summary, eye movement examination is very helpful for the diagnosis of PSP (9), and does not help as much for PD or MSA. Useful clues are:
Although pathologically proven cases of PSP without "abnormal eye movements" have been described, eye movements were usually not quite "normal." Indeed, these patients did not have a downward oculomotor palsy, but Birdy and colleagues (10) observed that they had a slowed downward-command saccades, square-wave jerks, slow horizontal saccades, and blepharospasm. This should be considered probable PSP, even if the best specificity for PSP (NINDS-SPSP) criteria are postural instability leading to falls within the first year of onset coupled with a vertical supranuclear gaze paresis (1,4).
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