Causes and Symptoms
There is a syndrome of a persistent sensation of a tickle in the larynx or throat when there is no visible lesion. When there is a chronic cough and a patient has been thoroughly examined (their pulmonary physician has verified there is no lung problem and their laryngologist or ENT has verified that there is no visible anatomic problem with the larynx or throat), then I believe the problem is likely from a nerve injury causing a phantom sensation. The patient coughs, but the sensation not only doesn't go away, but the cough leads to another cough. The coughing promotes itself in a positive feedback loop.
An analogy I use is where a person, through some mishap, loses their hand, but the nerve endings continue to make the brain feel as if the hand is still there. Nerves can send aberrant signals when injured. Neuromas are notorious for this type of phantom signal.
Treatment
I consider the use of amitriptyline as a medication to deal with chronic cough or chronic neurogenic pain; that is, pain that originates from a nerve. Amitriptyline, which was originally designed as an antidepressant, also seems to relieve chronic tickles and chronic nerve pain to a great degree, so at times, I will suggest trying this medication (it is not to treat you for depression). It does have a side effect of sleepiness.
Directions
I would like to maintain a patient on as small a dose as possible. In many people I am able to obtain relief from their symptoms with a rather small dose. Since one of the most significant side effect of the medication is sleepiness, I will start a patient on a single pill in the evening each day (a 10 mg pill). It is also a good idea to start on the weekend, so even if you are tired, it won't affect your work. I suggest taking the medication one or two hours before going to bed and thus, even if you become tired, you are going to sleep anyway. Some people complain of difficulty waking up the next morning. In many people, this side effect wears off after they've been on the medication for a week or so. In a few people it does not, which precludes us from using this medication to try to relieve their cough symptoms.
In general, I have a patient take one pill in the evening for three days. If symptoms of cough, throat tickle or pain are not being relieved at this dose, then you may increase to two pills each evening. You may continue to increase the dose every day or two by one pill. When symptoms are reduced by 80% of more, or if you reach 8 pills per evening, don't further increase the dose.
If there is break-through cough in the after noon or evening, you may add 10 mg or 20 mg in the middle of the day. (one or two pills).
If a patient's symptoms are relieved or improved, I suggest staying on the medication for at least one month beyond the cessation of the cough or pain symptom relief. Then try to taper off the amitriptyline gradually over a few days, perhaps between three and seven days. In a few patients, the symptoms return and they may resume taking the medication. In many patients, we will have broken the cycle of pain or tickle and they will not need to remain on any medication.