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Biomedical subjects

M Falcioni

Publications and source records attributed to M Falcioni.

At least 19 recordsLinked to original sources
PubMed2001

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.

Adult↗
PubMed2001

[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.

Adult↗
PubMed2000

Exit-time approach to epsilon-entropy.

An efficient approach to the calculation of the epsilon-entropy is proposed. The method is based on the idea of looking at the information content of a string of data, by analyzing the signal only at the instants when the fluctuations are larger than a certain threshold epsilon, i.e., by looking at the exit-time statistics. The practical and theoretical advantages of our method with respect to the usual one are shown by the examples of a deterministic map and a self-affine stochastic process.

Journal Article↗
PubMed2000

Library design in combinatorial chemistry by Monte Carlo methods.

Strategies for searching the space of variables in combinatorial chemistry experiments are presented, and a random energy model of combinatorial chemistry experiments is introduced. The search strategies, derived by analogy with the computer modeling technique of Monte Carlo, effectively search the variable space even in combinatorial chemistry experiments of only modest size. Efficient implementations of the library design and redesign strategies are feasible with current experimental capabilities.

Combinatorial Chemistry Techniques↗
PubMed2000

Chaos or noise: difficulties of a distinction

In experiments, the dynamical behavior of systems is reflected in time series. Due to the finiteness of the observational data set, it is not possible to reconstruct the invariant measure up to an arbitrarily fine resolution and an arbitrarily high embedding dimension. These restrictions limit our ability to distinguish between signals generated by different systems, such as regular, chaotic, or stochastic ones, when analyzed from a time series point of view. We propose to classify the signal behavior, without referring to any specific model, as stochastic or deterministic on a certain scale of the resolution epsilon, according to the dependence of the (epsilon,tau) entropy, h(epsilon, tau), and the finite size Lyapunov exponent lambda(epsilon) on epsilon.

Journal Article↗
PubMed2000

[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.

Adult↗
PubMed1999

Complications and their management in tympanomastoid surgery.

Chronic diseases of the ear and their surgical treatment can endanger the delicate structures of the temporal bone in close relationship with the middle ear. The experience and expertise of the otologic surgeon, based on perfect knowledge of the complex anatomy of the whole temporal bone, are unfortunately built up partly through the management of complications encountered in tympanomastoid surgery and may require knowledge of basic neuro-otologic procedures. Paralysis and paresis of the facial nerve and labyrinthine, and dural and vascular injuries may have consequences not only in the final result of surgery but also in endangering the patient's life. All major complications are discussed and some possible treatments are proposed. Minor complications affecting the temporomandibular joint, the dura, the external auditory canal, and the bony canal wall are also covered, along with some suggestions on how to keep these consequences within reasonable percentages.

Ear, Inner↗
PubMed1999

Infratemporal fossa approaches to the lateral skull base.

The infra-temporal fossa approach is one of the lateral approaches to the skull base. It is indicated for the treatment of tumors such as glomus tumor, petrous apex cholesteatoma, chondroma, lower cranial nerve neuroma and nasopharyngeal cancer. In the present paper, we described the surgical anatomy of the lateral skull base and the indications for the infra-temporal fossa approach with its variants. We showed the hints and pitfalls in the procedures. Five illustrative cases are also presented.

Adult↗
PubMed1999

[Facial nerve identification in the translabyrinthine approach: an alternative method].

Since the abrupt drop in the mortality rate as a result of the introduction of microsurgical dissection techniques in the treatment of acoustic neuromas, surgeons have concentrated their efforts on preserving hearing and facial nerve function. In the translabyrinthine approach, identification of the facial nerve at the fundus of the internal auditory canal is an important step for subsequent dissection. However, the identification techniques available to date carry with them some potential risk of facial nerve injury when performed by inexperienced surgeons. In addition, they are time-consuming procedures. The authors present an alternative method for identification of the facial nerve at the fundus of the internal auditory canal during the translabyrinthine approach. The superior ampullary nerve is interrupted at the superior cribrosa area where it is not in intimate relationship with the facial nerve. Medial reflection of the superior ampullary nerve and the superior vestibular nerve facilitates identification of the facial nerve and preparation of a vestibulo-facial dissection plane.

Cranial Nerve Neoplasms↗
PubMed1999

[Intrapetrous carotid artery aneurysm].

Intratemporal carotid artery aneurysms are rare lesions, with only 54 cases reported in the literature. Their most common symptoms are pulsatile tinnitus, hearing loss and signs of Eustachian tube obstruction. In case of aneurysm rupture, bleeding may be so profuse as to require emergency legation of the common carotid in the neck. Arteriography is the diagnostic gold standard for this disorder. Successful treatment usually involves selective aneurysm embolization or carotid closure with detachable balloons. The authors report a new case of intratemporal carotid artery aneurysm previously treated with selective embolization. To avoid the risk of aneurysm recanalization and/or infection through the external auditory canal, middle ear obliteration and blind-sac closure of the external canal were performed in this case.

Aged↗