Which of the following reflexes is typically affected in polyradiculoneuropathy (Guillain-Barré syndrome)?

The correct answer is B - Patellar reflex. In Guillain-Barré syndrome, the patellar reflex, also known as the knee-jerk reflex, is often affected. This reflex normally occurs when the doctor taps the patellar tendon, just below the kneecap, with a reflex hammer. In a healthy individual, this causes a brief contraction of the quardiceps muscle and a quick extension of the lower leg. However, in Guillain-Barré syndrome, the nerves responsible for transmitting this reflex signal can become damaged or dysfunctional due to the demyelination of peripheral nerves. As a result, the patellar reflex may be diminished or absent in individuals with Guillain-Barré syndrome, which is one of the clinical signs used in diagnosing the condition.