218 J. Anaesth. 2006; 50 (3) : 218 - 219 Indian
INDIAN JOURNAL OF ANAESTHESIA, JUNE 2006 218
CASE REPORT
ACOUSTIC NEUROMA PRESENTING AS REFRACTORY TRIGEMINAL NEURALGIA Dr. Ruchi Gupta1
Dr. Walia S. S.2
Dr. Dushant Thaman3
SUMMARY A 56-year old female presented to our pain clinic with history of shooting pain on face & neck for last 4-5 months and was on medical treatment without much relief. For diagnostic & therapeutic reasons we gave mandibular, maxillary & glossopharyngeal nerve block to which she responded partially. This made us to investigate the patient for other possibilities. Plain X-ray Skull AP view with mouth open showed bilateral elongated styloid process especially on rt. side. In order to look for vascular compression CT was done which showed Acoustic neuromas. MRI done showed right sided CP angle mass (extracannalicular schwannoma ) pressing on rt. trigeminal nerve. She was referred for gamma knife surgery by the neurosurgeon. Repeat MRI done after two months showed intracannalicular extension of acoustic neuroma.
Keywords: Trigeminal Neuralgia, Acoustic Neuroma, Refractory pain. Introduction Trigeminal Neuralgia is a common entity having varied aetiology like vascular malformation, dental diseases, post herpetic neuralgia etc.1 We present a rare case of acoustic neuroma presenting as refractory trigeminal neuralgia where imaging played an important role in the final outcome of the patient. Case report A 56-year old female presented to our pain clinic with history of shooting pain on right side of face and neck for last 4-5 months. She was on medical treatment with tab carbemazepine 200 mg thrice daily, Amitriptyline 75 mg night time and tab ultrazac (combination of paracetamol and tramadol) thrice daily. After taking treatment she did have relief for sometime but later it was ineffective. On examination she had neuralgic pain in the distribution of right maxillary and mandibular nerves along with otalgia, radiation to neck, anterior 1/3rd of tongue and pain on swallowing. The change of posture increased the pain. There were no associated symptoms of tinnitus, vertigo or hearing problems. For diagnostic and therapeutic reasons initially we gave mandibular and maxillary nerve block using local anaesthetic agents (bupivacaine 0.25%) with small amount of Steroid (triamcinolone 5 mg) each.2 She responded to
these blocks partially, at particular posture she was having pain. After one day we repeated the block but again pain relief was partial. On the following day she came back with pain more so on the tongue. She could not exactly differentiate anteriorly or posteriorly. This made us think of other possibilities. Glossopharyngeal nerve block was given, but again with partial results. Next possibility of facial nerve neuralgia was kept in mind. Since she was not responding we planned to investigate her. Plain X-ray skull AP view with mouth open was done which showed bilateral elongated styloid process especially on rt. side. CT scan was done in order to look for vascular compression but there was none, however, superior cuts based on high clinical suspicion revealed a right Cerebello- Pontine Angle (CP angle) mass. MRI done for further characterization
1. M.D., DNB, Prof. 2. D.A, M.D., Prof. & Head 3. M.S, Mch, Consultant Neurosurgeon Dept. of Anaesthesiology & Critical Care and Dept. of Neurosurgery. S.G.R.D Institute of Research and Medical Sciences, Amritsar – 143001. Punjab. Correspond to : Dr. Ruchi Gupta 314-A Block, Ranjit Avenue, Amritsar – 143001. Punjab. E-mail :
[email protected] (Accepted for publication on 18 - 5 - 2006 )
Fig. 1 : MRI Showing Acoustic neuroma pressing on right trigeminal nerve.
GUPTA, WALIA, THAMAN : ACOUSTIC NEUROMA AS REFRACTORY TRIGEMINAL NEURALGIA
showed 2.2×1.9×1.8 cm extracanalicular right sided Schwannoma / meningioma at CP angle pressing on rt. trigeminal nerve (fig. 1), intra cisternal 7th and 8th nerves could not be seen separate from the mass. She was refered to neurosurgeon, who sent her for gamma knife surgery. After two months patient came back for follow up. She did not undergo surgery rather had taken some homeopathic medicine. Although her symptoms were less in intensity but presently she had developed mild tinnitus. Repeat MRI showed intracannalicular extension of tumor with negligible increase in size 2.2×1.9×1.9 cm (fig. 2).
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compression, where instead, CP angle mass was detected. MRI showed right sided extracanalicular schwannoma / meningioma pressing on right trigeminal nerve. Further testing like ABR (Auditory Brainstem Response)5 were not done as our patient was not having any hearing loss, tinnitus or vertigo at that time. Out of the above two possible diagnosis the chances of its being extracanalicular acoustic neuroma was more because of its pattern of growth. In these cases facial nerve tends to be stretched over the top of the tumor while the trigeminal nerve is compressed as it exits from the lateral pons, caudal extention brings it into contact with 9th and 11th nerves. However this patient did not have any hearing symptoms, which has been reported with large acoustic neuroma on one side5 or may be because of its extracanalicular origin. Although meningiomas may also have similar presentation but they predominantly produce cerebellar signs, facial paresis or hydrocephalus.6 The repeat MRI which now showed intracannalicular extension also proved our point. As the result of this extension, it might have decreased pressure on the trigeminal nerve thereby decreasing intensity of symptoms, but led to development of tinnitus. The patient who was referred to neurosurgeon after complete evaluation and sent for gamma knife surgery,7 was again asked to undergo procedure before the size increases. To conclude, a proper history, careful physical examination and correctly chosen modern imaging techniques can be extremely beneficial in reaching the final diagnosis and affecting ultimate outcome of patient.
Fig. 2 : MRI Showing intracannalicular extention of Acoustic neuroma.
Discussion Orofacial pains can arise from a multitude of structures. Origin of pain may be neurologic in nature presenting as neuralgia or neuritis, or be referred to the orofacial area from intracranial pathology.3 One of the commonest cause of orofacial pain is trigeminal neuralgia which is also known as Tic Douloureux. It is characterized by sharp, severe (paroxysmal) pain on the face which lasts for no more than few seconds.4 When site of pain and source of pain are not same, it can be quite confusing to both the patient and the clinician.3 Since history in our patient was confusing and drug therapy ineffective we kept the possibility of vascular malformation, dental diseases, sinusitis, Eagle’s syndrome, geniculate neuralgia and tumors. We started with simple investigation like X-ray which showed slightly elongated styloid, which gave us a clue and we went for CT scan in order to look for vascular
References 1. Joshi M. eds Trigeminal Neuralgia. In; Text book of pain management. India, Paras Medical publishers, 2005: 69-73. 2. Waldman SD. The role of neural blockade in the mamagement of headaches and facial pains. Curr Rev Pain 1997; 1: 346-52. 3. Dunsky JL, Kahn CH. Orofacial pain. In; Mannual of pain management, eds Warfield CA, Fansett H J, Philadelphia, Lippincott W&W, 2ndedn. 2002: 56. 4. Waldman SD. Trigeminal Neuralgia. Intern Med 1992; 13: 45-53. 5. Hain TC. Acoustic Neuroma. www.dizziness and balance.com/disorders/tumors/acoustic_neuroma.htm 6. Mallucci C L, Ward V, Carney A S, Donoghue G M O, Robertson I. Clinical features and outcomes in patients with non-acoustic cerebellopontine angle tumours. Neurol Neurosurg Psychiatry 1999; 66: 768-71. 7. Noren G. Gamma knife radiosurgery for acoustic neuroma. Acta Neurochirg Suppl 1993; 58: 104-07. (www.anarchive.org/norenarticle.htm)
