Cough is one of the most common complaints that lead patients to see a doctor. It is not only a basic respiratory sign but also an important neurological sign. There are 3 main types of cough: reflex cough (type I), voluntary cough (type II), and evoked cough (type III). Reflex cough sensitivity may be increased in many neurological disorders, such as space-occupying lesion of the brainstem, medullary lesions secondary to type I Chiari malformations, tics disorders such as Tourette’s syndrome, somatic cough, neurodegenerative disorders of the cerebellum, and chronic vagal neuropathy due to allergic and nonallergic diseases. On the other hand, cough sensitivity decreases in the cerebral hypoxia, cerebral hemispheric stroke with a brainstem shock, dementia due to Lewy body disease, Parkinson’s disease, amyotrophic lateral sclerosis, multiple sclerosis, and peripheral neuropathy such as hereditary sensory and autonomic neuropathy type IV, diabetic neuropathy, vitamin B12, and folate deficiency. The ear-cough reflex of Arnold’s nerve, syncopal cough, cough headache, opioid associated cough and cough-anal reflex are signs that can help in the diagnosis of underlying neurological disorders. The cough reflex test is a quick, easy, and inexpensive test that can be performed during the cranial nerve exam. In this article, we have discussed cough reflex testing and various neurological disorders that increase or decrease cough sensitivity.
