A patient involved in a road traffic accident presents with quadriparesis, sphincter disturbance, sensory level up to the upper border of sternum and a respiratory rate of 35/minute. The likely level of lesion is :
**Core Concept**
The patient's presentation suggests a spinal cord injury (SCI) with quadriparesis, sphincter disturbance, and a clear sensory level, indicating a specific level of lesion. This condition requires a thorough understanding of spinal anatomy and the effects of SCI on respiratory function.
**Why the Correct Answer is Right**
The patient's symptoms suggest a lesion at the level of the 5th thoracic vertebra (T5), as indicated by the sensory level up to the upper border of the sternum. This level of lesion typically affects the sympathetic outflow from the T1-T4 spinal segments, leading to Horner's syndrome. The patient's respiratory rate of 35/minute is elevated, indicating respiratory muscle weakness, which is often seen in SCI patients with lesions above T6. The involvement of the diaphragm and intercostal muscles, innervated by the phrenic nerve (C3-C5) and intercostal nerves (T1-T11), respectively, is consistent with a lesion at the T5 level.
**Why Each Wrong Option is Incorrect**
* **Option A:** A lesion at the level of the 1st lumbar vertebra (L1) would result in a sensory level around the umbilicus, not the upper border of the sternum.
* **Option B:** A lesion at the level of the 1st thoracic vertebra (T1) would result in a sensory level around the clavicle, not the upper border of the sternum.
* **Option C:** A lesion at the level of the 5th cervical vertebra (C5) would result in a sensory level around the shoulder, not the upper border of the sternum.
**Clinical Pearl / High-Yield Fact**
In SCI patients, the level of lesion can often be estimated by the sensory level and the presence of Horner's syndrome. The American Spinal Injury Association (ASIA) classification is a useful tool for assessing the severity of SCI.
**Correct Answer: C. T5**