Answer for CoW 26 March 2017
BRACHIAL PLEXUS INJURY POST TRAUMATIC PSEUDOMENINGOCELE – PREGANGLIONIC NERVE ROOT AVULSION
Findings
Preganglionic nerve root avulsion with pseudomeningocele noted involving C6, C7, C8, D1 nerve roots levels of right brachial plexus. STIR hyperintensity and stretch injury changes seen in trunks, divisions and cord level of right brachial plexus. STIR hyperintensity/edema noted in supraspinatus, infraspinatus, subscapularis muscles and posterior para spinal muscles on right side and right scalenus anterior and scalenus medius muscles.
Discussion
Brachial plexus is the main sensory and motor innervation of the upper extremity. It may be involved in a variety of traumatic and nontraumatic pathologies. MRI is useful both in diagnosis and in localization of these lesions. This makes a significant impact on the management. Normal anatomy: The brachial plexus is formed by the ventral roots of C5 to T1 nerve roots. These unite to form three trunks. The trunks split into three anterior and three posterior divisions. These unite to form the three cords that further divide into five peripheral nerves. The roots and trunks are supraclavicular in location while divisions are retroclavicular and the cords are infraclavicular. Traumatic Brachial Plexus Injury: The common causes of brachial plexus injuries are road traffic accidents and birth palsy. Brachial plexus injuries can be divided into pre- and postganglionic lesions. The preganglionic lesions are avulsion of the nerve roots at their origin while postganglionic lesions may be lesions in continuity or nerve ruptures. The patient may have a combination of both pre- and postganglionic lesions. It is important to differentiate between pre and postganglionic lesions to determine the prognosis and plan further management. Postganglionic lesions in continuity without disruption of nerve fibers have good prognosis and recover spontaneously with conservative management. Postganglionic lesions with disruption of nerve fibers are treated with surgical repair, that is, nerve grafting with good results. Preganglionic lesions are usually treated with nerve transfers to restore function of the denervated muscles. Pseudomeningoceles are formed due to extravasation of cerebrospinal fluid through tear of the perineural sheath. These are seen on T2-weighted images as fluid-intensity lesions at the site of nerve root avulsion. However, presence of a pseudomeningocele is not always seen in nerve root avulsion and vice versa. Neuropraxic injury is seen as T2 hyperintense signal in the roots, trunks, or cords with or without enlargement . Nerve ruptures are seen as discontinuity in the neural structures. Associated findings of denervation edema in the muscles may be seen. Brachial plexus injuries may be associated with injuries to the subclavian artery due to their anatomical proximity to each other. Also post-traumatic pseudoaneurysm of subclavian artery may present with delayed brachial plexus paralysis due to compression of the brachial plexus.
Findings
Preganglionic nerve root avulsion with pseudomeningocele noted involving C6, C7, C8, D1 nerve roots levels of right brachial plexus. STIR hyperintensity and stretch injury changes seen in trunks, divisions and cord level of right brachial plexus. STIR hyperintensity/edema noted in supraspinatus, infraspinatus, subscapularis muscles and posterior para spinal muscles on right side and right scalenus anterior and scalenus medius muscles.
Discussion
Brachial plexus is the main sensory and motor innervation of the upper extremity. It may be involved in a variety of traumatic and nontraumatic pathologies. MRI is useful both in diagnosis and in localization of these lesions. This makes a significant impact on the management. Normal anatomy: The brachial plexus is formed by the ventral roots of C5 to T1 nerve roots. These unite to form three trunks. The trunks split into three anterior and three posterior divisions. These unite to form the three cords that further divide into five peripheral nerves. The roots and trunks are supraclavicular in location while divisions are retroclavicular and the cords are infraclavicular. Traumatic Brachial Plexus Injury: The common causes of brachial plexus injuries are road traffic accidents and birth palsy. Brachial plexus injuries can be divided into pre- and postganglionic lesions. The preganglionic lesions are avulsion of the nerve roots at their origin while postganglionic lesions may be lesions in continuity or nerve ruptures. The patient may have a combination of both pre- and postganglionic lesions. It is important to differentiate between pre and postganglionic lesions to determine the prognosis and plan further management. Postganglionic lesions in continuity without disruption of nerve fibers have good prognosis and recover spontaneously with conservative management. Postganglionic lesions with disruption of nerve fibers are treated with surgical repair, that is, nerve grafting with good results. Preganglionic lesions are usually treated with nerve transfers to restore function of the denervated muscles. Pseudomeningoceles are formed due to extravasation of cerebrospinal fluid through tear of the perineural sheath. These are seen on T2-weighted images as fluid-intensity lesions at the site of nerve root avulsion. However, presence of a pseudomeningocele is not always seen in nerve root avulsion and vice versa. Neuropraxic injury is seen as T2 hyperintense signal in the roots, trunks, or cords with or without enlargement . Nerve ruptures are seen as discontinuity in the neural structures. Associated findings of denervation edema in the muscles may be seen. Brachial plexus injuries may be associated with injuries to the subclavian artery due to their anatomical proximity to each other. Also post-traumatic pseudoaneurysm of subclavian artery may present with delayed brachial plexus paralysis due to compression of the brachial plexus.
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
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Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!