49

49 CASE 49


A 37-year-old man comes to the physician’s office complaining of chronic pain in the upper and middle back, headaches, muscle weakness in the hands, and loss of sensitivity to hot and cold temperatures.


About 2 years ago, the patient began to feel fatigued and found it hard to perform everyday tasks. Recently, he accidentally scalded his young daughter at bath time when he didn’t realize the water was hot. This prompted him to seek medical attention.



PHYSICAL EXAMINATION



VS: T 37°C, P 60/min, R 14/min, BP 120/80 mm Hg

PE: Loss of sensitivity, especially to hot and cold; muscle weakness and spasticity; headaches; a thoracic kyphoscoliosis. The loss of pain and temperature sensitivity is bilateral and symmetrically distributed in the upper extremities and thorax in a “cape-like” pattern.


LABORATORY STUDIES



Skull and cervical spine radiographs: Thoracic scoliosis and osteoporosis

MRI: Focal cord enlargement due to an intramedullary neoplasm


DIAGNOSIS


Syringomyelia



PATHOPHYSIOLOGY OF KEY SYMPTOMS


The patient’s symptoms are a combination of defects in afferent sensory transmission and efferent motor transmission, indicating a defect within the nerves or spinal cord. Unilateral symptoms would be indicative of a nerve problem. This patient’s symptoms are bilateral and are most likely due to a problem within the spinal cord.


Spinal cord sensory transmission ascends predominantly in the dorsal columns and the anterolateral tracts. Sensory nerves that transmit the modalities of fine touch, vibration, and proprioception enter the spinal cord at the dorsal root and ascend ipsilaterally to the medulla. A second-order sensory neuron crosses the midline forming the medial lemniscus and carries the information to the thalamus. The tertiary sensory neuron ascends from the thalamus to the somatosensory cortex. In contrast, pain and temperature sensory inputs travel through the anterolateral pathway. Sensory neurons enter the dorsal root and synapse in the dorsal horn of the gray matter of the ipsilateral cord. Second-order neurons send their axons across the midline to the contralateral anterolateral tract in which they ascend to make synaptic connection in the thalamus. The third neuron in the pathway projects to the somatosensory cortex. The anterolateral system is highly divergent; and as the pathway ascends, collaterals relay information to many targets, including the reticular formation and periaqueductal gray matter of the brain stem. Within the spinal cord, somatotopic organization is maintained, because nerve fibers originating from the upper parts of the body are carried in the more medial portions of the tract and nerve fibers originating from the lower parts of the body are carried in the more lateral portions of the tract (Fig. 49-1).


image

FIGURE 49–1 Comparison of the two major ascending somatosensory tracts. Left, Dorsal column-medial lemniscal tract. Right, Anterolateral tract. Note that the dorsal column tracts do not cross the midline until the level of the medulla, whereas the anterolateral tracts cross at the spinal cord level.

< div class='tao-gold-member'>

Related posts:

  1. 21
  2. 39
  3. 51
  4. 71

Stay updated, free articles. Join our Telegram channel
Tags:
Jul 4, 2016 | Posted by in PHYSIOLOGY | Comments Off on 49

Full access? Get Clinical Tree
Get Clinical Tree app for offline access