The role of nervus intermedius in side specific nasal responses

Abstract

Introduction. Nervus intermedius (NI) dysfunction is common in patients who have had vestibular schwannoma (VS) surgery.1 Such patients have a unilateral parasympathetic‐denervated nasal cavity. A number of side‐specific nasal reflexes have been demonstrated in normals, including hand cold water immersion.2 It is not understood whether these reflexes have parasympathetic or sympathic efferent pathways.Objectives. To evaluate the side specific nasal reflex to cold‐water immersion in post‐operative VS patients with NI dysfunction, in order to determine the nature of the efferent pathway of these reflexes.Method. The study of Wilde2 was repeated in 10 normal controls. Then a cohort observational study with internal controls was designed to evaluate the role of nasal parasympathetic innervation in patients who had unilateral VS surgery and NI dysfunction (Schirmer's test). Side specific response to cold‐water immersion was tested by acoustic rhinometry.Results. A consistent pattern of ipsilateral congestion and contralateral decongestion after the cold water immersion was seen in normals (P < 0.001 for both responses.) We found no consistent response in 18 VS patients on testing with stimulus ipsilateral to side of NI dysfunction and contralateral (the internal control).Conclusions. We confirm the consistent side‐specific nasal reflexes to cold water hand immersion in normals. This is disturbed in individuals following unilateral VS surgery with NI dysfunction. We have also shown that the contralateral side‐specific reflex is disturbed in these patients. These data suggest that the reflex is parasympathetic and crosses the midline.References.1 Irwing R.M., Viani L., Hardy D.G., Baguley D.M. & Moffat D.A. Nervus intermedius function after vestibular schwannoma removal: clinical features and pathophysiological mechanisms. Laryngoscope 105, 809–8132 Wilde A.D. (1999) The effect of cold water immersion on the nasal mucosa. Clin. Otolaryngol. 24, 411–413