We went through the comments made in the letter to the editor section regarding our article “Difficulty in shaving: a rare complication after total laryngectomy” published in the month of November 2009. The author has expressed his reservations about our diagnosis and feels that traumatic neuroma of the internal laryngeal nerve could be the most likely cause for the cough in our case. We beg to differ from him and strongly stand by our diagnosis.

A bit of pathophysiology of traumatic neuroma needs to be understood before we go on. Traumatic neuroma, an attempt by an injured nerve to regenerate, may present as a palpable nodule or an area sensitive to touch . When a nerve is transected, distal axons suffer Wallerian degeneration attributed to inflammatory response, whereas the axons and Schwann cells of the proximal stump proliferate. Under normal conditions, the 2 segments eventually meet; and the distal stump recovers innervation. However, if there is a scar tissue between them or if the stump is lost (as in amputation or distal end of laryngeal nerves as in total laryngectomy), the nerve proliferation continues from the proximal stump without finding its assembly point, producing a disorganized cell tangle composed of neural fibers and connective tissue that extends into the surrounding soft tissues until it forms an amputation neuroma .

We have gone through the article by To and Das Gupta who have mentioned clearly that there was a superficial larger network of fibers that appeared to be the regrowth of part of the cervical nerve plexus. We believe that these cervical nerve fibers are from the upper transverse cutaneous nerve of the neck (C2, C3) acting as the distal end of the cut nerve, and the cut end of the superior laryngeal nerve is the proximal end. The authors have pointed out the hypersensitive zone as well. We believe that their case is also pointing out toward cross innervation rather than traumatic neuroma alone. Neuromas take years to form after initial injury, as nerve regeneration is a slow process . Our patient presented within 4 months after total laryngectomy with cough on touch and shaving the upper neck, which is too short a period for neuroma to develop.

Most of the available reports in the literature are case reports describing the presentation and location of the traumatic neuromas after neck dissection . They appear as palpable nodules posterior to internal or common carotid artery. Description of the course and topographic distribution of the transverse cutaneous nerve of the neck and anatomy of the superior laryngeal nerve further supports our theory of cross innervation (Gray’s anatomy). Without cross innervation, the patient cannot develop severe bouts of cough on touching the upper part of the neck flap area and inferior border of the mandible. Our patient, unlike the one mentioned by To and Das Gupta, never had cough at rest; nor was his cough aggravated by neck movements. Injection of 2% xylocaine around the granuloma area temporarily stopped the cough. Traumatic neuroma without associated cross innervation cannot cause cough on skin stimulation, as internal laryngeal does not supply the neck. We agree that we did not encounter the branching nerve fibers or the nodule-like nerve thickening on exploring the patient. But the patient’s symptoms completely disappeared after the excision of the granuloma and elevation of the upper flap around the granuloma that must have divided the cross-innervating fibers.

We had initially written in detail regarding the case. As the reviewer wanted us to be brief, we had to cut down certain details. The excised granuloma was sent for histopathology, and it was reported as granulation tissue. There was no evidence of neuroma. The topographic distribution is also mentioned in the text, that is, in and around the granuloma and upper part of the entire neck on the right side until the inferior border of the mandible, which corresponds to the distribution of transverse cutaneous nerve of the neck. The presence of granuloma at the site of hyoid or being medial to carotid does not contradict the possibility of cross innervation. We agree that, in this era of evidence-based medicine, beliefs and hypothesis need to be substantiated with scientific proof. But unfortunately, histopathology does not identify the exact nerves involved in cross nerve innervation, which can only be known by the functional assessment.