Professional and Linguistic Assessments Board (PLAB) Practice Exam

Which condition is associated with the loss of corneal reflex?

1. Acoustic neuroma

2. Multiple sclerosis

3. Diabetic neuropathy

4. Optic neuritis

The correct answer is: Acoustic neuroma

The loss of the corneal reflex is notably associated with acoustic neuroma. This condition is a benign tumor that typically arises from the vestibular portion of the eighth cranial nerve (vestibulocochlear nerve). As the tumor grows, it can impact adjacent structures, including the trigeminal nerve (fifth cranial nerve), which plays a crucial role in mediating the sensory components of the corneal reflex. The corneal reflex is an involuntary blinking response that occurs when the cornea is irritated—such as by a light touch. The sensory input is provided by the ophthalmic branch of the trigeminal nerve (V1), and the motor response is mediated by the facial nerve (seventh cranial nerve). When the trigeminal nerve is compromised—as it can often be in the case of an acoustic neuroma—this response diminishes or is lost altogether, leading to a loss of the corneal reflex. In contrast, while conditions like multiple sclerosis, diabetic neuropathy, and optic neuritis can affect various neurological functions, they do not directly cause the loss of the corneal reflex in the same way that an acoustic neuroma does. Multiple sclerosis may impact neurological pathways but is more likely to cause fluctuating symptoms