"Person-in-the-Barrel" Syndrome: A Case Report of Bilateral Arm Paresis Due to Vasculitis With a Review of Pathological Mechanisms

"Person-in-the-barrel" syndrome is a descriptive term for bilateral arm (brachial) paresis in the absence of lower extremity (crural) weakness or bulbar (medullary) weakness. This phenomenon is associated with various descriptive terms such as "distal field infarction", "flail limbs", and "cruciate paralysis". Arriving at a specific diagnosis is a fascinating exercise in anatomical localization. Strategic lesions involving the watershed zones of the motor frontal lobes and the pyramidal decussation at the cervico-medullary junction are the classic sites of injury. However, peripheral causes such as motor neuron disease, mononeuritis multiplex (vasculitis), bilateral brachial plexopathy, and critical illness myopathy have been sporadically reported and can stochastically inflict the motor nerves or muscles of the upper extremities. In this report, we present a case of vasculitis with weakness restricted to the upper extremities and also delve into the neuropathological mechanisms of "person-in-the-barrel" syndrome.