REIDER PART 261

Chapter 8_Ceryical and Thoracic Spine 321

index and the long fingers in the patients palm and ask him or her to squeeze thesc digits as tightly as possible (Fig. 8-34A). This method is sometimes difficult to quan-titate and may be painful for the examiner if the patient is very strong.

An alternative method is for the examiner to place his or her flexed fingers against the patients palm and ask the patient to make a tight fist. This causes the examiner’s and the patient s fingers to be hooked together in a recip-rocal manner. The examiner then instructs the patient not to allow the fist to be pulled open and then attempts to do so (see Fig. 8-34B). In most normal patients, the examiner is unable to overcome the patient s grip.

T1 Nerve Root. The Tl nerve root exits the spine through the T1-T2 neuroforamen. Tl motor function is usually assesscd by testing the strength of the interosseous mus-cles, which govern abduction and adduction of the fingers. Finger abduction can be tested most easily by asking the patient to hołd both hands out and spread the fingers as far apart as possible. The examiner then grasps the patients spread fingers between the examiner’s thumb and index finger and attempts to push them back together while the patient resists maximally (Fig. 8-35A). Normally, the examiner should be able to overcome the patient s efforts to maintain finger abduction with a moderate degree of difficulty. With this technique, both hands may be tested simultaneously and the strength of abduction compared.

An alternative technique is to test the first dorsal interosseous in isolation. To test the first dorsal interosseous, the examiner stabilizes the patients hand with one of the examiner’s own hands and places the index finger of the examiner s other hand against the radial aspect of the patienfs index finger. The patient is then instructed to press the index finger being tested against the examiner’s finger as hard as possible (see

Fig. 8-35B). Not only can the strength be assessed by this method but also the contraction of the first dorsal interosseous can be confirmed visually or by palpation.

Finger adduction is also a motor function of the Tl nerve root. To test it, the examiner places an index card between the patient s extended long and index fingers and instructs the patient to squeeze the two fingers together as tightly as possible. The examiner then proceeds to with-draw the card from between the fingers, estimating the force required (see Fig. 8-35C). Normally, the examiner should be able to withdraw the card but with some difficulty.

Lower Thoracic Newe Roots. Motor function of spe-cific thoracic nerve roots is not normally assessed. Beevor’s sign, howevcr, may be used to screen for asym-metric loss of thoracic root motor function. Beevor’s sign is a gross test of muscular innervation from the thoracic spine. In this test, the patient is asked to do a half sit-up with the knees flexed and the arms bchind the head (Fig. 8-36). In the normal patient, symmetric coordinated abdominal muscle contraction should keep the umbilicus in the midlinc during this maneuver. Compression or destruction of a thoracic ncrve root, such as might be caused by osteophytc or tumor, results in weakness of the museulature in the dermatome innervated by that root. This causes the umbilicus to deviate toward the stronger uninvolved side. This deviation is called Beevor’s sign. Asymmetric weakness of the museulature innervatcd by the thoracic nerve roots may also be seen in cases of spinał dysraphism or poliomyelitis.

Reflex Examination

Biceps Tendon Reflex (C5). The biceps tendon reflex is usually used to assess the C5 nerve root. However, because the C6 nerve root also contributes to innervation of the biceps, the C5 radiculopathy may only result in

Figurę 8-34. Assessing C8 motor function. A, Long finger flexors. B, Alternative technique.