Diagnostic Approach to Acute Neurological Deficits

Primary Recommendations

The American College of Radiology recommends MRI of the left forearm and brachial plexus without contrast to evaluate for peripheral nerve pathology in patients with acute neurological deficits and a history of trauma, as it is superior for soft tissue evaluation and can detect neuromas, nerve compression, or intraneural pathology 1, 2
The American College of Radiology suggests including T2-weighted sequences to identify nerve edema or masses, T1-weighted sequences to characterize tissue characteristics, and STIR sequences for detecting inflammation or fluid collections in the MRI protocol 1, 3

Peripheral nerve pathology, such as neuroma formation, nerve entrapment, or delayed nerve compression, should be considered in patients with acute neurological deficits and a history of trauma, as these conditions can cause significant morbidity 1
The presence of complete loss of finger flexion and extension suggests median and ulnar nerve dysfunction, while a primarily extension deficit suggests posterior interosseous nerve involvement, and a primarily flexion deficit suggests anterior interosseous nerve involvement 1
Vascular complications, such as compartment syndrome or vascular injury with delayed ischemic neuropathy, should also be considered in the differential diagnosis 1, 4

MRI of the cervical spine with contrast should be obtained if the forearm MRI is unrevealing, as it can reveal subtle inflammatory or vascular lesions that may not be visible on non-contrast sequences 1, 2
Electrodiagnostic studies, including nerve conduction studies and EMG of the left upper extremity, can help localize the level of nerve injury and differentiate axonal from demyelinating pathology 1

Assuming that a normal brain and cervical spine MRI excludes all central pathology, as MRI can miss subtle cord lesions, particularly without contrast 1, 2, 5
Delaying imaging of the forearm/brachial plexus, as early identification of compressive lesions allows for timely surgical intervention if needed 1, 2
Failing to obtain contrast-enhanced imaging if initial studies are unrevealing, as contrast can reveal inflammatory, infectious, or vascular pathology not visible on non-contrast sequences 1, 2