The Laryngoscope Lippincott Williams & Wilkins, Inc. © 2007 The American Laryngological, Rhinological and Otological Society, Inc. Cranial Nerve Involvement in Malignant External Otitis: Implications for Clinical Outcome Navin Mani, MRCS; Holger Sudhoff, MD, PhD; Sandeep Rajagopal, MRCS; David Moffat, BSc, MA, FRCS; Patrick R. Axon, MD, FRCS Background: Malignant external otitis is an un- common, potentially lethal infection of the temporal bone primarily affecting elderly diabetic patients. Ob- jective: To determine whether cranial nerve involve- ment in malignant external otitis affects or predicts the clinical outcome in terms of morbidity and mor- tality. Methods: Diagnosis of malignant external otitis was established in 23 patients (average age, 71 yr; range, 39 – 87) based on inclusion criteria of severe pain, otitis externa refractory to conventional treat- ments, diabetes mellitus, and Pseudomonas aerugi- nosa detection. Computed tomography confirmed temporal bone involvement extending outside the external auditory canal. Data Analysis: Retrospec- tive analysis of hospital records. Results: Ten of 23 (43.5%) patients showed cranial nerve involve- ment. The following cranial nerves were affected: facial nerve (6/10), lower cranial nerves (combina- tion of IX, X, XI, XII) (3/10), and extended nerve palsy (VI, VII, IX, X, XI) (1/10). Thirteen of 23 (56.5%) patients displayed no cranial nerve in- volvement. All patients were treated with long- term, high-dose antibiotic treatment dependent on the microbiological findings. Conclusions: All patients with lower cranial nerve palsy recovered normal function; however, the facial nerve palsy was significantly less likely to improve by medical treatment. Cranial nerve involvement did not af- fect the patient survival rate under an optimized medical treatment in our series. Key Words: Malig- nant external otitis, diabetes mellitus, cranial nerve palsy, high-dose antibiotic treatment, exter- nal ear canal. Laryngoscope, 117:907–910, 2007 INTRODUCTION Malignant external otitis is an uncommon, poten- tially fatal infection of the temporal bone that most commonly affects elderly diabetic patients. It starts in the external auditory canal and then extends into the temporal bone and the adjacent structures. 1 Skull base osteomyelitis may result from progression of the initial infection. 2 Meltzer and Kelemen 3 described a case of progressive Pseudomonas osteomyelitis of the temporal bone in a di- abetic patient in 1959. In 1968, Chandler 4 clinically de- fined the entity in a review of 13 patients. The causative organism is most commonly Pseudomonas aeruginosa, al- though other organisms such as Proteus mirabilis, As- pergillus fumigatus, Proteus sp., Klebsiella sp., and staph- ylococci have been isolated. 5 Clinical manifestations include severe otalgia, otor- rhea, and possible cranial nerve involvement. There is a strong association with diabetes mellitus, other immuno- compromising conditions, or advanced age. Elderly diabet- ics are the group most likely to be affected, and this is thought to be related to small vessel angiopathy in the ear canal. 4,6 Spread of infection into the temporal bone occurs through the fissures of Santorini and the tympanomastoid suture, leading to involvement of the stylomastoid and jugular foramina. Venous channels and fascial planes fa- cilitate the spread of infection along the dural sinuses, eventually extending to the petrous apex. Involvement of cranial nerves occurs because of their proximity to the site of infection. The facial nerve is the most commonly involved cranial nerve and has been thought to occur because of involvement as it exits the stylomastoid foramen. 4 As the infection spreads along the skull base, it can affect the glossopharyngeal, vagus, and spinal accessory nerves as they pass through the jugular foramen. 7 The hypoglossal nerve can also become affected within the hypoglossal canal. Rarely, the abducens and trigeminal nerves may be involved at the petrous apex. 8 The diagnosis of malignant otitis externa is made from a combination of clinical, laboratory, and radiologic From the Department of Otolaryngology and Skull Base Surgery, Addenbrooke’s Hospital, Cambridge, U.K. Editor’s Note: This Manuscript was accepted for publication January 19, 2007. Send correspondence to Dr. Patrick R. Axon, Department of Otolar- yngology and Skull Base Surgery, Addenbrooke’s Hospital, Cambridge, UK. E-mail: patrick.axon@addenbrookes.nhs.uk DOI: 10.1097/MLG.0b013e318039b30f Laryngoscope 117: May 2007 Mani et al.: Cranial Nerve in Malignant External Otitis 907