Trigeminal neuralgia. Non-invasive techniques versus microvascular decompression. It is really available any further improvement?

Analysis of the results of the various methods for treatment of typical trigeminal neuralgia (TN) based on the literature and personal experience. The personal experience includes 847 cases: total thyzotomy in the posterior fossa 17 cases; rhyzotomy in the posterior fossa sparing the intermediate fibers 16 cases; microvascular decompression (MVD) 141 cases; controlled thermorhizotomy (PTR) 54 cases; Fogarty Balloon compression (FBC) 223 cases; glycerol ganglyolis (PGG) 12 cases; miscellaneous 48 case; medical treatment only 310 cases; cyberknife radiosurgery (CKR) 46 cases. The follow-up in this series is 1-32 years. MVD of the Vth cranial nerve in posterior fossa gives the best results in term of long-term pain relief without collateral effects in drug-resistant TN. Percutaneous techniques (PTR, PGG, FBC) are indicated in patients either without neurovascular conflict or with excessive surgical risk. Stereotactic radiosurgery (SRS) and CKR might be considered an improvement of percutaneous and surgical techniques, but contrary to the expectations, the rate of complete pain relief at long term is lower. SRS and CKR are less effective than MVD which, in spite of the risks it entails, remains the choice treatment for typical trigeminal neuralgia.

Results by motor cortex stimulation in treatment of focal dystonia, Parkinson's disease and post-ictal spasticity. The experience of the Italian Study Group of the Italian Neurosurgical Society.

Extradural motor cortex stimulation has been employed in cases of Parkinson's disease (PD), fixed dystonia (FD) and spastic hemiparesis (SH) following cerebral stroke. Symptoms of PD are improved by EMCS: results were evaluated on the basis of the UPDRS and statistically analysed. In PD EMCS is less efficacious than bilateral subthalamic nucleus (STN) stimulation, but it may be safely employed in patients not eligible for deep brain stimulation (DBS). The most rewarding effect is the improvement, in severely affected patients, of posture and gait. FD, unresponsive to bilateral pallidal stimulation, has been relieved by EDMS. In SH reduction of spasticiy by EMCS allows improvement of the motor function.

Extradural motor cortex stimulation (EMCS) for Parkinson's disease. History and first results by the study group of the Italian neurosurgical society.

The preliminary results obtained by the Study Group for Treatment of Involuntary Movements by Extradural Motor Cortex Stimulation (EMCS) of the Italian Neurosurgical Society, are reported. The series includes 16 cases of very advanced Parkinson's Disease (PD), aged 46-81; 15 of them were not eligible for Deep Brain Stimulation. Ten cases have been evaluated at 3-30 months after implantation. Unilateral, sub-threshold extradural motor cortex stimulation (2 8 Volt, 100-400 microsec., 20-120 Hz) by chronically implanted electrodes, relieves, at least partially, but sometime dramatically, the whole spectrum of symptoms of advanced PD. Tremor and rigor bilaterally in all limbs and akinesia are reduced. Standing, gait, motor performance, speech and swallowing are improved. Benefit is marked as far as axial symptoms is concerned. Also the symptoms of Long Term Dopa Syndrome -dyskinesias, motor fluctuations - and other secondary effect of levodopa administration psychiatric symptoms - are improved. Levodopa dosage may be reduced by 50%. The effect seems persistent and does not fade away with time. Improvement ranged, on the basis of the UPDRS scale, from <25% to 75%. There was only one case of complete failure. Quality of life is markedly improved in patients who were absolutely incapable of walking and unable arise out of chair. After stimulation they could walk, even if assistance was necessary. Improvement was observed also in those with disabling motor fluctuation and dyskinesias which could be abolished.

Recurrent spinal cord tethering by sacral nerve root following lipomyelomeningocele surgery. Case report.

A 21-year-old woman had recurrent progressive weakness/hypesthesia and pain in both lower extremities. At the age of 5 and 19 years, she had undergone surgical resection of a lipomyelomeningocele at L5-S1. Surgical exploration revealed that the cord was tethered and pulled over to the side by an excessively short right S-1 nerve root. The contralateral L-5 and S-1 nerve roots were markedly stretched. Division of the right S-1 nerve root resulted in prompt disappearance of pain in the lower extremities and improvement in neurological function.

Mapping of sensory responses to epidural stimulation of the intraspinal neural structures in man.

A database is presented of sensory responses to electrical stimulation of the dorsal neural structures at various spine levels in 106 subjects subjected to epidural spinal cord stimulation. All patients were implanted for chronic pain management and were able to perceive stimulation in the area of pain. All patients entered in this study were able to reliably report their stimulation pattern. Several patients were implanted with more than one electrode array. The electrode arrays were placed in the dorsal epidural space at levels between C-1 and L-1. The structures that were likely involved include the dorsal roots, dorsal root entry zone, dorsal horn, and dorsal columns. At the present time, exact characterization of the structure being stimulated is possible only in limited instances. Various body areas are presented with the correspondent spine levels where implanted electrodes generate paresthesias. Areas that are relatively easy targets for stimulation are the median aspect of the hand, the abdominal wall, the anterior aspect of the thigh, and the foot. Some areas are particularly difficult to cover with stimulation-induced paresthesias; these include the C-2 distribution, the neck, the low back, and the perineum.

Further experience with extradural motor cortex stimulation for treatment of advanced Parkinson's disease. Report of 3 new cases.

AIM: To report the results obtained with the extradural motor cortex stimulation in Parkinson's disease. METHODS: Three patients were submitted to MRI images and functional MRI in order to identify the upper limb motor area. Then a quadripolar electrostimulator was introduced in the extradural space, through 2 burr holes. RESULTS: Unilateral, extradural motor cortex stimulation relieves, at least partially, but sometime dramatically, the whole spectrum of symptoms in advanced Parkinson disease: tremor and rigor bilaterally in all limbs; akinesia; standing, anteropulsion, gait; motor performance; dysphagia; speech and swallowing. Also the symptoms of long term dopa syndrome--dyskinesias, and other secondary effect of L-dopa administration, psychiatric symptoms--are improved. CONCLUSION: The results seems do not fade away with time. Drug dosage may be reduced by 50%. We suggest early employ of transdural motor cortex stimulation.

Ultrasonic aspiration in the surgical treatment of intracranial tumors.

The CUSATM (Cavitron Corporation - Stamford, Conn., USA) has been used for aspiration and ultrasonic fragmentation in 52 cases of intracranial tumors: 24 meningiomas, 20 gliomas, 5 acoustic neurinomas, 1 cerebral metastasis, 1 pinealoma, 1 pituitary adenoma in our Clinic, since January 1979. Several advantages of the CUSA were found as compared to conventional techniques: it provides good visibility of the operating field: pathologic tissue can be removed from the surface to the deep structures and only one instrument is present in the surgical cavity; its use reduces manipulation, traction and thermic effects on nearby tissue; it selectively spares major vessels and has a hemostatic effect on those less than 1 mm in diameter. The rapidity of the action of the CUSA is relative to the consistency of the tissue. Tumors of high consistency are very slowly removed by the CUSA, and its use is not worthwhile. In our cases no damage to the surrounding structures was evident. Preliminary experimental data suggest that the use of the CUSA be avoided near the brain stem or within the spinal cord. However, in a cervical ependymoma of our series, the CUSA provided complete removal of the mass without complications. This result was achieved by using lower vibratory power: we were thus able to remove pathologic soft tissue without clinically evident damage to the surrounding structures. In some particular situations the volume and the shape of the instrument can be a hindrance, and some modifications are suggested: a bayonet shape and longer tip would facilitate the reaching of deep structures and permit its use in transphenoidal surgery; incorporation of a cautery in the tip, so that contemporary hemostasis can be accomplished. Our experience indicates that the use in transphenoidal surgery; incorporation of a cautery in the tip, so that contemporary hemostasis can be accomplished. Our experience indicates that the use of the CUSA is better indicated in deep tumors: meningiomas of the base of the skull, acoustic neurinomas, pinealomas, pituitary adenomas. In gliomas it is very useful in the selective removal of the neoplastic tissue in functionally important areas.

Chronic triventricular hydrocephalus: morphological and functional study before and after ventriculoperitoneal shunting.

We have neuroradiologically and neuropsycho-physiologically studied a case of chronic hydrocephalus due to congenital acqueductal stenosis, before and after ventriculoperitoneal shunting. The aims of the study were: 1) to point out the correlation between neuroimaging (Computerized Tomography/Magnetic Resonance Imaging) and mapping of Computerized Spectral Analysis EEG (CSA-EEG); 2) to monitor evoked bioelectrical activity by neurophysiological evaluation of acoustic and visual N1 and P3. Both bioelectrical activity and neuroimaging evaluation showed a considerable recovery of the neurobiological substratum after neurosurgical shunting, while neuropsychological investigation showed a slight improvement in all cognitive tasks.

Multifactorial analysis of epidural spinal cord stimulation.

In order to provide a data bank to allow a more precise and effective implementation of spinal cord stimulation, a computerized analysis of 1,375 combinations obtained from electrode arrays located in the thoracic and cervical epidural area was performed. 67 electrode arrays implanted in 34 subjects were subjected to analysis. During the stimulation trial, all the available combinations were systematically tested and the results entered into a computerized database. The study was not meant to analyze the clinical results or the indications of epidural spinal cord stimulation. Parameters studied include position of each electrical contact as related to midline, vertebral level of each contact, distribution of stimulation-induced paresthesiae, and electrical parameters (voltage, rate, pulse width, perception threshold, discomfort threshold, usage range). Analysis of the data allow the surgeon (1) to define the characteristics of the stimulation-induced paresthesiae; (2) to define the spectrum of the electrical parameters used to stimulate the spinal cord; (3) to define the population of implanted electrode arrays/contacts; (4) to study objectively how the position of the electrodes within the spinal canal, their vertebral level and the interelectrode distance affect the electrical parameters and the stimulation-induced responses. The multifactorial systematic analysis of such a large number of combinations provides the basis for further developments in the area of electrical stimulation of the nervous system.

Intraoperative electrical stimulation for functional posterior rhizotomy.

Intraoperative electrical stimulation of dorsal spinal roots from L1 to S1 bilaterally was performed in 80 patients affected by cerebral palsy, in whom spasticity was the main symptom. Clinical examination and EMG recordings showed three main features of reflex responses. We know that they indicate respectively a normal presence, a defect or an excess of inhibitory activity within the spinal circuits examined. Only those roots or rootlets involved in circuits where normal inhibitory processes are reduced or absent are surgically sectioned. Therefore these circuits are interrupted. The theoretical bases and long-term results indicate that this method is a useful and correct approach to the neurosurgical therapy of spasticity. It allows us to utilize a new important criterion to identify the roots or rootlets to be sectioned, based not on the anatomic, but on the functional selection.

Cryoanalgesia. Ultrastructural study on cryolytic lesion of sciatic nerve in rat and rabbit.

The sciatic nerve was exposed to cryoinjury at different freezing patterns in albino rats and rabbits and the frozen nerves were serially examined with electron microscopy from the time of cryolitic lesion (--60 degrees C for 3 minutes) for up to 28 days. The cryolesion was characterized by a total degeneration of the myelin fibers, while non-myelin fibers and vessels seemed less affected. Regeneration began 8 days after cryolysis. A peculiar pattern was the absence of Schwann cells, while the basal membrane around regenerating axons remained intact. The hypothesis that the basal membrane might play a role is discussed.