gms | German Medical Science

Acoustic neuroma (AN) or schwannomas usually arises from the vestibular division of the eight cranial nerve. They are most prevalent in older age groups of fifth decade and above. Acoustic neuroma can occur as sporadic or as part of clinical complex in neurofibromatosis type 2 (NF2). In latter situation patients usually presents as an earlier age and sometimes with bilateral tumor. Sporadic or non NF2 vestibular schwannomas are very rare in children and adolescents. Malignant schwannomas can occur both in the presence and absence of NF2 [Ref. 1].

AN accounts for about 6% of all intracranial tumors and due to the recent improvment in imaging technique the calculated incidence is 17.4/1000000 as reported in recent study by Tos and Coll [Ref. 2]. The sporadic AN clinical presentation usually is in adult age, and even if it is very difficult to ascertain, it’s very rare in young age because symptoms are often mild and can mimic otitis media, Deafness and tinnitus goes unnoticed for months or years until other symptoms develop.

We found description in the english literature of 34 cases (age from 6 to 16 y.o.) of non-malignant, non-NF2 sporadic acoustic neuromas in pediatrics and adolescent patients [Ref. 3], [Ref. 4], [Ref. 5], [Ref. 6], [Ref. 7], [Ref. 8], [Ref. 9], [Ref. 10], [Ref. 11], [Ref. 12], [Ref. 13], [Ref. 14], [Ref. 15], [Ref. 16], [Ref. 17], [Ref. 18], [Ref. 19], [Ref. 20], [Ref. 21], [Ref. 22], [Ref. 23], [Ref. 24], [Ref. 25], [Ref. 26], [Ref. 27].

Altough the dimensions non always is reported (no mention of the dimension in 13 cases) correctly, 21 cases are from 1.7 to 8 cm. Presenting symptoms of the reported cases: deafness in 24 cases, tinnitus in 8 cases, cerebellar signs in 19 cases.

During the 25 years period from 1978 to 2003 two thousand different skull base procedures were performed by the Department of Otolaryngology, Opedali Riuniti di Bergamo, Bergamo, Italy. Among these cases there were 10 cases acoustic neuromas in pediatric and adolescent patients. We excluded the NF2 and malignant schwannoma from our current study. The clinical, radiological, audiological and follow up data of our 10 cases were retrospectively reviewed (see Table 1 [Tab. 1], Table 2 [Tab. 2]).

Under the age of 16 years, acoustic tumor represents 0.8% of all childhood tumors and 2.08% of all unilateral acoustic neuromas [Ref. 11]. The earliest clinical feature of acoustic neuroma in children, as in adults, is usually a progressive sensorineural hearing loss. However, as so often is the case with any type of unilateral hearing loss and expecially in children, the deficit may go unnoticed by the child or the parents. The suspicion of an intracranial lesion comes only after other more overt signs of space-occupying lesions become apparent, such as gait instability, nystagmus and cranial nerve deficits. Headache is also not uncommon with large tumor. Occasionally, early deafness in childhood passes unnoticed or become attributed to middle ear disease [Ref. 16]. Hence a high index of suspicion should be maintained when evaluating a child with unilateral sensoneural hearing loss and poor speech in discrimination [Ref. 20]. Embolisation of these tumor may be attempted to reduce the blood supply [Ref. 16], [Ref. 19]. Unilateral sensorineural hearing loss, unilateral absent acoustic reflexes, and abnormal unilateral or bilateral ABR recording is always pathognomic and should be subjected to ABR [Ref. 21]. Males outnumber female; in contrast it has been well documented that females are more common than males in cases of acoustic neuroma as a whole [Ref. 22]. Cranial nerve symptoms other than the eight cranial nerve, such as facial nerve palsy, trigerminal nerve symptoms and cerebellar ataxia are more common in cases with acoustic neuroma in childhood [Ref. 22]. Although eradication of the tumor should be the first priority in the treatment of acoustic neuroma in a child, functional preservation of the facial nerve and cochlear function should also be taken into consideration [Ref. 22]. In our series we found that preservation of facial nerve functions is more easier in pediatric and adolescent than adult patient (7 patients with House-Brackmann grade 1) while hearing preservation is low in this series (20% over 60% in adult series).

The surgical approaches in reported case were: retrosigmoid in 20 cases, translabyrinthine in 6, middle cranial fossa in 1, retrosigmoid plus middle carnial fossa in 1 case. In our series 5 cases were treated by transalabyrinthine approach and 5 by retrosigmoid approach as an attempt to the hearing preservation.

Respect to the adults cases, it is a difficult surgery with several complications: 1 cerebellar oedema that required temporary ventricolo-peritoneal shunt (retrosigmoid approach with the tumor of 1 cm in cerebello –pontine angle); hemiparesis in 1 case due to bleeding after the removal of 60 mm. Tumor that required revision surgery with resolution; meningitis in 1 case teated with antibiotics; cerebrospinal fluid rhinorrea in a retrosigmoid approach without hearing preservation that rquired Eustachian tube exenteration by middle cranial approach. Sometimes the tumor clivage were difficult for the thickness of arachnoid.

In conclusion we can observe that the tumors mean dimension is higher than in adult population. It probably is due to the diagnostic delay as well as tumor fast growth. It is a difficult surgery with several complications. Sometimes the clivage can be difficult and, probably for this reason, hearing preservation is low.

We must have an high suspicious index. Diagnostic delay must be avoided. It is mandatory to exclude NF2 with imaging (brain and spine) and other clinical tests.