Canalplasty for severe external auditory meatus exostoses

Exostoses of the external auditory meatus is a well known condition which infrequently requires surgical correction. However, the stenosis caused by severe exostosis can affect quality of life considerably and may require surgical intervention. Canalplasty, in such a situation, is a valid and effective management option. In our series the commonest indication for surgery was recurrent otitis externa. The detailed surgical technique is described and a retrospective analysis of 65 such procedures is presented. There were only two significant complications, both post-operative stenosis, requiring further corrective surgery. In conclusion, canalplasty for the exostosis of the external auditory meatus is a safe surgical option.

Glomus tympanicum tumour: an alternative surgical technique

Glomus tympanicum tumour is one of the commonest neoplasms of the middle ear. It is more common in females. The most common presenting symptom is pulsatile tinnitus. A retrotympanic mass is found in the middle ear in all the cases. Computed tomography (CT) scan is the investigation of choice, however in difficult cases magnetic resonance imaging (MRI) can be helpful. Surgery is regarded as the gold standard of treatment in spite of the fact that radiation therapy has also been advocated in the literature. In this series 17 cases of glomus tympanicum treated at Gruppo Otologico Piacenza - Rome (Italy) were analysed retrospectively. A simple and safe technique has been described. All the cases were female and treated by surgery. The tumour was removed completely in all the cases and the ossicular chain kept intact. Recurrence was encountered in only one case after nine years. Surgical removal of the tumour is recommended as the treatment of choice with the following advantages: complete removal, a low complication rate, a low recurrence rate, acceptable hearing level and minimum morbidity.

[Preoperative imaging in chronic otitis surgery]

High resolution computed tomography (CT) is presently the most accurate technique to study the temporal bone. Nevertheless, there is no general agreement about its usefulness in pre-operative evaluation of chronic otitis media. Indeed, if we rule out some exceptions, CT is not fundamental for diagnosis which can often be obtained through an accurate otomicroscopy. The Otology Group in Piacenza applies the following absolute indications for pre-operative CT in chronic otitis media: 1) difficult otomicroscopy evaluation; 2) suspected petrous bone cholesteatoma; 3) dubious diagnosis; 4) suspect of malformations; 5) review of cases that had previously undergone mastoidectomy; 6) suspected intracranial complications and/or meningoencephalic herniation (in this case also a magnetic resonance imaging must be performed). With the exception of these specific conditions, pre-operative CT is useless in cases of simple chronic otitis. However, when a cholesteatoma is suspected, CT can provide the surgeon, particularly when inexperienced, useful, but not indispensable, informations. Pre-operative knowledge of these informations can allow a more accurate evaluation of the case, with a better planning of the surgical procedure, in order to ensure a more specific informed consent. Finally, the Authors point out the fact that surgeon must be able to interpret by his own the CT data to have a real advantage by this examination.

[Enlarged translabyrinthine approach in large acoustic neurinomas]

The translabyrinthine approach has long been, and in some centers is still, considered inadequate for the removal of large acoustic neuromas (AN). Over the years, with experience, the original technique has been modified, extending the approach to what is now called the enlarged translabyrinthine (ET) approach. Applying these modifications, between April 1987 and February 2000, the Gruppo Otologico in Piacenza, Italy removed 132 ANs, 3 cm or larger, from the cerebello-pontine angle. These tumors accounted for 25.9% of the 510 cases of AN to undergo surgery during that period. Of the 132 cases only one patient died and the percentage of complications was very low, generally lower than analogous series published in the literature. Such complications were progressively reduced in time, leading to a significant reduction in the length of post-operative hospitalization: on the average the 8.8 days were reduced to 5.7 in the last 43 cases. Ipsilateral preoperative hearing, inevitably sacrificed using the ET approach, was already significantly compromised in more than 65% of the cases. On the basis of the present data, it can be asserted that tumor diameter does not in any way preclude the use of the ET approach in AN surgery, rather the reduced morbility and shorter post-operative hospitalization make it the approach of choice for large ANs.

Electromyographic evaluation of facial nerve damage in acoustic neuroma surgery

OBJECTIVE

This study aimed to determine whether postoperative facial nerve paralysis or surgical manipulation causing paralysis could be predicted on train responses during intraoperative facial nerve monitoring in acoustic neuroma surgery.

STUDY DESIGN AND SETTING

This was a prospective study performed at a tertiary referral center.

PATIENTS AND METHODS

Train responses were recorded on a floppy disk and compared with postoperative facial nerve function in 51 patients who underwent enlarged translabyrinthine acoustic neuroma surgery.

MAIN OUTCOME MEASURES

The number, duration, frequency, and peak-to-peak amplitude of train responses were analyzed and compared with postoperative facial nerve function.

RESULTS

Trains were observed in 42 of 51 patients. Six of seven patients with high-amplitude trains more than 250 microV, and three of five patients with bomber-type high-frequency trains elicited during tumor dissection from the facial nerve or stretching the nerve, showed severe facial nerve dysfunction. On the other hand, seven of the nine patients with no trains also showed severe facial nerve dysfunction.

CONCLUSIONS

The presence of high-amplitude or high-frequency trains elicited by surgical manipulation to the facial nerve seems to indicate a critical situation for the facial nerve. However, certain types of mechanical trauma resulting in severe facial nerve paralysis cannot be identified by train responses.

Identification of internal acoustic canal in the middle cranial fossa approach: a safe technique

BACKGROUND

The middle cranial fossa approach (MCFA) is a very valuable functional approach in the armamentarium of the neuro-otologic surgeon. Identification of the internal acoustic canal (IAC) in MCFA is one of the most tedious steps. Many techniques have been described to locate the IAC safely when using the MCFA.

OBJECTIVE

We sought to describe a safe technique for identification of the IAC and to demonstrate its feasibility in temporal bone dissections, as well as to discuss our clinical experience with this technique.

METHODS

The surgical anatomy of the 20 temporal bones were evaluated and measured, especially by defining the medial and lateral ends of the IAC and relations to the nearby located structures. Measurements were obtained at 3 levels: the width of the IAC at the level of the fundus, the width of the IAC at the level of the porus, and the safe distance around the IAC at the meatal level. The medial and lateral IAC end widths were compared with each other and with the safe area at the meatal level.

RESULTS

The smallest, the largest, and the mean values were recorded. The mean width of the IAC at the level of the porus was found to be more than 3-fold that of the width of the IAC at the level of the Bill's bar, and the ratio between the width of the medial safe area around the IAC and the lateral end of the IAC was found to be more than 7-fold as wide.

CONCLUSION

This technique offers direct quick exposure of the IAC, without handling the facial nerve and the inner ear structures. Forty-five cases of operations with the same technique showed excellent ease and safety of identifying the IAC medially in the MCFA.

Morphological characteristics and distribution of the autonomic and sensitive innervation of the prostate in some animal species

The sensitive and autonomic innervation of the prostate was studied in some mammals (rat, rabbit, horse, donkey and bull) using gold chloride impregnation. In all the species considered the gland was supplied with conspicuous innervation located in the thickness of the capsule and in trabeculae. The autonomic innervation was constituted by ganglion cells of different sizes (small, medium and large), isolated or in groups of large ganglia also, always located along the course of nerve bundles. The sensitive nervous component, placed more frequently in the most superficial layer of the capsule, consisted of delicate networks originating by more fibres and, above all, of capsulated receptors such as Pacini and Golgi-Mazzoni corpuscles. A characteristic finding, but only present in the horse, donkey and bull, was the helicoidal disposition of thin collagen fibres around thin nervous bundles that ended up to the point where the nerve trunk divided.

Identification of the facial nerve in the translabyrinthine approach: an alternative technique

An alternative technique for the identification of the facial nerve at the fundus of the internal auditory canal is described.

[Treatment of residual acoustic neurinomas]

Generally the main objective of acoustic neurinoma (AN) surgery is to totally remove the tumor associated with minimum morbidity. Nevertheless, in some cases residual tumor fragments are intentionally or accidentally left in place. These residues can lead to new growth. The present study provides a retrospective analysis of 14 cases of residual AN have undergone surgery at the Otology Group in Piacenza from 1987 to 1999. All these patients had previously undergone at least one retrosigmoidal exeresis although only one had been performed at the Otology Group. All patients except 1 were affected by anacusia at the time of surgery. The list of post-operative deficits included 2 hemipareses, 3 irreversible facial paralysis with consequent corneal opacity in 2 cases, 1 dysmetria and 1 paralysis of the abducent nerve. The patients had also undergone the following additional treatments: 1 emergency revision to drain a cerebellar hematoma, 3 ventricle-peritoneal derivations, 1 double application of stereotactic radiotherapy and 2 surgical procedures for facial plasty. Ten cases underwent the revision surgery at the Otologic Group using a translabyrinthine approach and 4 using a transcochlear approach. Tumor removal was deemed complete in all cases. The sole post-operative complications were a subcutaneous hematoma at the point where abdominal fat was removed and a temporary paralysis of the abducent nerve. Post-operative hospitalization was an average of 6.9 days. Analysis of the results showed that AN must be operated at selected centers in order to reduce the post-operative neurological deficit and the percentage of residual tumor. It also indicated that the retrosigmoid approach has a higher risk of accidentally leaving tumor residues than the other approaches. Finally, in the presence of a residual AN, the translabyrinthine approach offers the greatest advantages.

On the bulky appliances and artero-venous anastomoses in the vascular district of the base of the brain

It has been studied the vascular territory of the base of the brain and it has been pointed out the presence of characteristical structural arrangements of the vasal wall and artero-venous anastomoses. The just mentioned characteristical structures are placed in points where a vessel divides itself or creates a collateral branch and their functional engagement is target-oriented to control the blood flux.