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Clinical Case

CLINICAL CASE | 41-Year-Old Man With Burns on Finger Tips and Bilateral Upper Extremity Analgesia

Approximately 1 year earlier, a 41-year-old man sustained a painless burn to his right hand. The patient reported, at the time, that as the cigarette he was holding burned down, he noticed that his right index and middle fingers had sustained a burn, although he felt no pain. He reported that he noticed no other sensory, especially touch, or motor problems at that time. Over the next year, he began experiencing reduced right-hand grip strength in addition to the sensory loss. Then he sought medical care.

Neurological examination revealed an extensive bilateral territory over the upper limbs and neck where there was minimal pain and thermal sensation (see Figure 5–1A). The analgesic region extended from the C5 to the T1 dermatomes (see Figure 4–5). At this time, upper extremity tactile sensation and limb proprioception were now affected. Motor testing revealed denervation of several intrinsic right-hand muscles.

T2-weighted MRI (Figure 5–1B) shows a central region of hyperintense signal in the cervical spinal cord centrally, and extending longitudinally, corresponding to an accumulation of CSF-like fluid. Note that this region should be distinguished from other areas where the hyperintense signal is produced normally by CSF within the subarachnoid space.

Answer the following questions based on your reading of this chapter and prior chapters, inspection of the images, and consideration of the neurological signs.

1. Distinguish the neural systems that mediate pain and temperature sensations from touch and proprioception.

2. Identify the anatomical location of the accumulated fluid that is producing the hyperintense signal.

3. What are the key differences in the location of axons of the pain and temperature pathway and the touch/proprioception pathway and how does their locations explain the neurological signs?

4. Why is the sensory sign bilateral?

5. Explain why the patient initially experienced only a loss of pain sensation but later experienced a loss of strength and touch?

Conclusion: The person was diagnosed with syringomyelia. The classical distribution of pain and temperature loss in cervical syringomyelia is across the arms bilaterally. In this neurological condition, there is an accumulation of CSF-like fluid that produces a cavity, termed syrinx.

Key neurological signs and corresponding damaged brain structures Bilateral loss of pain and thermal senses, together with loss of tactile and proprioceptive senses and hand weakness, as the syrinx expands

Initially, the syrinx selectively damages the decussating anterolateral fibers producing the bilateral loss of pain and temperature senses; sparing touch and proprioceptive afferents in the dorsal columns. Figure 5–1C is a schematic illustrating the location of a typical syrinx in relation to decussating second-order axons of the anterolateral pathway. The central darkened region corresponds to the size of the syrinx when the patient first noticed pain loss, without additional neurological signs. One year later, because of its enlarged size, the syrinx extends into the dorsal columns, thereby producing tactile and proprioceptive loss. ...

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