Inconsistent MRI findings in acute pre-Willisian brain ischemia in rabbit: a useful model?

BACKGROUND

We have investigated a model of "preterminal ischemia" in order A) to assess the MRI findings and the repeatability of the anatomical changes as showed by MRI, and B) to compare the data so obtained with the humans.

METHODS

Twenty rabbits were used. Under general anesthesia, the occlusion of 1) the two common carotid arteries (from 2 hours up to 24 hours) was performed in 8 cases, and of 2) the epi-aortic vessels at the aortic arch (from 2 hours up to 4 hours) was performed in 4 cases in general anesthesia.

RESULTS

In the vessels occlusion group MRI study showed inconsistent, inconstant, predominantly ill defined, linear and/or spotlike hyperintense deep cerebral alterations, variable in location, unilateral and bilateral in 8 cases. Although in carotid occlusion the damage was already evident within the first two hours, aortic arch occlusion was unable to produce global brain lesional pattern even up to 4 hours. MRI study of the sham operated animals was negative.

CONCLUSIONS

The selective vulnerability of mesial deep cerebral structures to hypoxia, different in location from the human's, and the more effective pre-Willisian compensation, suggests to look for different animals when dealing with preterminal ischemic models comparable to the humans' as studied with MRI.

Thoracoscopic approaches to the thoracic spine

Microsurgical approaches for the treatment of pathology located in the ventral thoracic spine using video-assisted thoracic surgery (VATS) allow neurosurgeons to access the disc spaces, vertebral bodies, paravertebral soft tissues, spinal cord, spinal nerves, and sympathetic chain with minimally invasive surgery. This has been associated with substantial clinical benefits including reduced postoperative pain, lower complication rates and shorter recovery times when compared with standard thoracotomy techniques. This article describes the experience at our institution with VATS for discectomy (20 cases), corpectomy and spinal reconstruction (8 cases), thoracic sympathectomy (3 cases), and nerve sheath tumor removal (1 case). The technique can be mastered but requires surgeons to learn the new psychomotor skills needed to perform endoscopic spine surgery. The learning curve is steep. Special training in instructional seminars, surgical skill laboratories, and clinical preceptorships is needed before this surgical approach can be used clinically to treat spinal pathology. VATS has significant advantages compared to standard thoracotomy, including reduced incisional pain and avoidance of the postthoracotomy pain syndrome. If intercostal neuralgia develops postoperatively, it is milder and usually transient compared to the pain associated with standard thoracotomy. Better cosmetic outcomes, earlier mobilization, and faster recovery are added benefits. The surgical techniques are relatively new for neurosurgeons and require dedicated practice to master them. Once the surgical skills are perfected, VATS is feasible for spinal pathology and can be performed safely and effectively.

[Diffuse axonal lesions in childhood]

OBJECTIVE

About 48% of all primary traumatic intracranial lesions are represented by so-called Diffuse Axonal Injury (DAI): a pathologic condition characterized by multiple microscopic lesions and hemorrhage at the level of midline cerebral structures, in the subcortical grey matter, and/or within the brainstem. The natural history of DAI is depressing: 100% of the patients deteriorate rapidly to coma and approximately 50% die, while 50% remain in a vegetative state or with severe neurological deficits. In the present report, we describe the results of a study aimed to evaluating the cerebral hemodynamics and the neuroradiological findings observed in four children (6, 8, 10 and 12 years old) affected by DAI.

METHODS

All the patients had been admitted to the Pediatric Intensive Care Unit with Glasgow Coma Score (GCS) of 5. On admission, all patients underwent mechanical ventilation, antiedemigen and barbiturates therapy. Serial CT scan and Transcranial Doppler Sonography (TCD) examinations were carried out in all children. TCD of the middle cerebral arteries was performed through the temporal window. The children underwent insertion of a ventricular catheter for intracranial pressure monitoring. Follow-up time has been, respectively, 4 years, 3 years, 7 and 1 months.

RESULTS

The Glasgow Outcome Score (GOS) of three children is 2 (persistent vegetative state), while the GOS of the one child is 3 (severe neurological deficits).

CONCLUSION

DAI results in unfortunate prognosis and large health care costs. The proper medical management of this condition should be based on TCD and SjO2 and CEO2 evaluations, in order to monitor efficaciously the cerebral blood flow.

Cervical cord compression due to atypical primary neuroectodermal tumor (PNET): one-stage removal and combined cervical spine stabilization. Case report

INTRODUCTION

The neuroectodermal tumor of bone constitutes a recently isolated neoplasm, which morphologically resembles the peripheral neuroepithelioma of soft tissue. The diagnosis is made by excluding readily classified small round cell neoplasms and then demonstrating the neural origin of the tumor by means of ultrastructural or immunocytochemical studies.

CLINICAL CASE

We report a case of a primary neuroectodermal tumor (PNET) with atypical findings (primary cervical location, massive vertebral body infiltration and isolated neurological symptomatology). Total tumor removal was achieved by means of a one-stage three-level laminectomy (partial C5, total C6-C7), C6 somatectomy, and combined anterior and posterior cervical spinal instrumentation and fusion.

CONCLUSIONS

Our case presents three peculiar features: 1) isolated myelopathic symptomatology (first case described); 2) primary isolated massive vertebral cervical involvement with intraspinal epidural extension (first case described); 3) one-stage tumor resection, fusion and instrumentation. Since radiation therapy causes tumor shrinkage but is not curative, radical removal is mandatory even with complex instrumentation procedures.

[Tetanus: problems of differential diagnosis in the presence of contemporaneous administration of metoclopramide]

Here we report a clinical case concerning differential diagnosis between tetanus and metoclopramide intoxication. A 67 year old woman was admitted to our intensive care unit complaining of both trisma and four limbs hypertone soon after a massive metoclopramide bolus administration. The patient was affected by a chronicle renal insufficiency and a diagnosis of metoclopramide intoxication was made. The long lasting dystonic symptomatology together with respiratory insufficiency ruled out the hypothesis of drug overdose. The intensive care physicians would take into account that at least a 24 hours clinical observation is mandatory in order to perform a correct diagnosis.

Cerebral blood flow velocities and trigeminal ganglion stimulation. A transcranial Doppler study

Transcranial Doppler sonography (TCD) patterns of middle cerebral arteries (MCA) were recorded in 10 patients before and during unilateral trigeminal ganglion stimulation (TGS). During TGS, TCD flow velocity significantly decreases in all patients: on both sides in 2 patients, only ipsilaterally to the TGS in 7 patients, and only on the opposite side in the remaining patient. In 2 patients, a controlled progressive hypercapnia test was performed before and during TGS. An enhanced vascular response to increased CO2 concentrations was observed during TGS.

[Transcranial Doppler sonography in neurotraumatology: hemodynamic monitoring of diffuse axonal injury]

Six patients with diffuse axonal injury, ranging in age 8 to 29 years, hospitalized in emergency in our Polyclinic with a Glagow coma score under 8, were examined. Patients were intubated and connected to an automatic respirator. They underwent serial cranial CT and transcranial Doppler sonography recordings using the temporal window with insonation of the two middle cerebral arteries. During the period of observation, the metabolic processes and systemic hemodynamics were maintained within the limits of homeostasis. In all cases and at different times, osmotic diuretics (18% mannitol), barbiturates and hyperventilation therapy were administered. In 5 patients over 6 (80%) increased blood flow, variously sensitive to barbiturates, was detected associated to increased resistance index secondary to intracranial hypertension. Based on Doppler findings four patients underwent surgical treatment: ventriculostomy for monitoring of intracranial pressure or decompressive craniectomy. According to this experience, the use of transcranial Doppler US is mandatory for a correct identification of the hemodynamic injury associated to diffuse axonal injury, for planning the medical and/or surgical approach and for assessment of the successful results of therapeutic management.

[Cerebral vasospasm and intracranial hypertension: transcranial Doppler ultrasonographic findings]

Four consecutive patients with subarachnoid hemorrhage were studied by serial cranial CT and transcranial Doppler ultrasonographic recordings. Patients were in the age range 52 to 67 years. According to Hunt and Hess scale the clinical status varied between grade I and IV. Increase in intracranial pressure "masked" the hemodynamic signs of cerebral vasospasm, reappeared after normalization of intracranial pressure following therapeutic management. Based on the reported findings transcranial Doppler ultrasonography should be considered an indispensabile diagnostic procedure however inadequate for monitoring the natural history of vasospasm complicated by intracranial hypertension.

"Filtering effect" of cerebrospinal fluid on spinal somatosensory evoked potentials: case report

A 31-year-old man presented complaining of radicular (L4) pain. MRI and myelo-TC of the thoraco-lumbar spine showed the presence of an extradural CSF cyst extending from Th6 to L2, posterior to the cord. The patient underwent a Th12 laminectomy, the cyst was opened and drained. A recording electrode was placed epidurally, dorsal to the cyst, at the level of the Th12 vertebral body, and the potentials evoked by stimulation of the tibial and saphenous nerves were monitored during surgery. After cyst drainage the epidural potentials were significantly larger (x5) in amplitude and more defined in shape than those recorded in the presence of the cyst. Our case demonstrates the "filtering effect" of CSF on spinal somatosensory evoked potentials.

Spinal cord stimulation in the treatment of paraplegic pain

Twenty-five patients suffering from intractable pain due to a chronic spinal cord lesion underwent a percutaneous test of spinal cord stimulation. At the end of the test period, 40.9% of the patients reported a mean of 65% pain relief and these patients were selected for ongoing stimulation. At a mean follow-up time of 37.2 months the success rate, based on the number of patients with more than 50% pain relief, had fallen to 18.2%. Pain relief rates were analyzed in relation to quality of pain, neurological status, level and extent of the lesion, and electrode level to identify prognostic factors that could improve the clinical usefulness of spinal cord stimulation. Patients experiencing painful spasms or a constrictive type of pain and with incomplete thoracic lesions were found to be the best candidates for spinal cord stimulation.

Spinal cord stimulation in low back and leg pain

We have reviewed our experience with spinal cord stimulation (SCS) in patients with low back and leg pain. 33 patients complaining of leg and low back pain underwent percutaneous tests of SCS. 28 patients had failed back surgery syndromes, 1 patient had pain related to an L1 vertebral body fracture, another from Tarlow cysts and the remaining 3 patients had lumbosacral spondyloarthrosis and osteoporosis without radiological signs of root compression. 28 patients showed mono- or pluriradicular deficits. At the end of the test period (5-65 days), 21 patients (63.6%) reported more than 50% of pain relief (mean analgesia 75%) and were submitted to chronic stimulation. The mean follow-up was 45.5 months. At maximum available follow-up, 40% of the patients (13 out of the 33 initial patients) were successfully using the stimulator (mean analgesia 66.6%).

Spinal cord stimulation and cerebral blood flow: an experimental study

Spinal cord stimulation (SCS) affects peripheral, coronary and cerebral blood flow (CBF) in humans. In 1986 Meglio et al. [Appl Neurophysiol 1986;49:139-146] advocated a functional reversible sympathectomy as one of the mechanisms of SCS in man. An experimental animal model was developed to study SCS effects on CBF and to investigate the possible mechanisms. Twenty-one white New Zealand rabbits were anesthetized with Fluothane; spontaneous ventilation was permitted. A steady hemodynamic and metabolic state was maintained. A small cervical laminectomy was performed and an electrode (Medtronic Sigma 3483) was placed in the epidural space over the posterior spinal cord. Both common carotid arteries were exposed and external carotid arteries were ligated. In 3 animals, the cervical symapthetic trunk (CST) was exposed and wrapped with bipolar hook-stimulating electrodes. SCS was performed for 20 min with electrical square waves of 210 microseconds duration, 80 cycles/s, at 2/3 motor threshold intensity. CST stimulation was delivered for 1 min with the following parameters: 10 V, 10 cycles/s, 0.5 ms duration. CBF velocities of both internal carotid arteries were measured by using a CW Doppler (in all the animals) and electromagnetic flowmeter (in 2 animals), at rest, during sympathetic trunk stimulation, during SCS, during simultaneous SCS and CST stimulation. During SCS, an increase of CBF was detected in 11 rabbits (52.4%); a decrease was observed in two cases (9.5%). No change was detected in the remaining 8 animals (38%). CST stimulation induced a decrease of CBF in all animals. Electromagnetic flowmetry confirmed velocitometric findings in the 2 cases studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Increase of cerebral blood flow and improvement of brain motor control following spinal cord stimulation in ischemic spastic hemiparesis

A 64-year-old man had an ischemic stroke in the left parietotemporal cortical-subcortical areas. He developed a severe right spastic hemiparesis and dysphasia. An angiographic study showed left internal carotid artery occlusion and right internal carotid artery stenosis. A right internal endoarteriectomy was performed without any clinical improvement. After 1 year the patient was a candidate for cervical spinal cord stimulation (SCS) for the treatment of his spastic hemiparesis. An epidural electrode (Medtronic Sigma 3483) was positioned at the cervical level, mediodorsal to the cord. Clinical and neurophysiological studies (surface polyelectromyography, PEMG, for evaluation of brain motor control) were performed before and after 7 days of SCS (0.2 ms, 80 c/s, intensity for paresthesiae, continuous mode). A transcranial Doppler (TCD) study of both middle cerebral arteries (MCA) at rest and during SCS was performed on two occasions. SCS was followed by improvement of voluntary movement, decrease of spasticity and better endurance. The clinical findings were confirmed by the PEMG recordings. TCD examination showed an increase of flow velocities on both the right MCA (+43%) and the left MCA (+130%) during SCS. Such a TCD pattern, suggesting an increase of cerebral blood flow (CBF) during SCS, was reproducible. This case confirms efficacy of SCS in the treatment of ischemic hemiparesis and the increase of CBF following cervical SCS in man. The marked increase of CBF, particularly evident on the ischemic side, may play a role in mediating the improvement of motor control in our patient together with a possible arousal of the so-called 'sleeping neurons' of the penumbra zone.

Microvascular decompression for trigeminal neuralgia: prognostic factors

A series of 66 patients with trigeminal neuralgia (TN) treated by microvascular decompression (MVD) is analyzed in order to define the importance of various prognostic factors. A typical pattern of pain, presence of facial hypaesthesia and previous ablative trigeminal procedures showed an unfavorable influence on the results of MVD. Duration of symptoms was longer in patients who failed to benefit from MVD. Pain distribution and the type of vascular compression did not influence the outcome.

Intracerebral injury following thermocoagulation of the trigeminal ganglion

An unusual postoperative complication of percutaneous thermocoagulation of the gasserian ganglion is reported. Computed tomography and magnetic resonance imaging of the brain disclosed an intracerebral lesion following the surgical procedure. Some rare abnormalities of the skull base could increase the risk of such complications. A meticulous surgical technique with fluoroscopic and neurophysiological control is mandatory in any percutaneous procedure on the trigeminal ganglion.

Spinal neurenteric cyst in association with syringomyelia: case report

A case of spinal neurenteric cyst in association with Klippel-Feil deformity, spinal lipoma, and syringomyelia is presented. Neuroradiological evaluation was performed by means of magnetic resonance imaging of the spine and a computed tomography myelograph. The diagnosis of neurenteric cyst was established by histological and immunohistochemical studies. The pathogenesis of syringomyelia associated with an extramedullary mass lesion is discussed.

Spinal cord stimulation and cerebral haemodynamics

An increase of regional cerebral blood flow (rCBF) has been shown to occur in man during spinal cord stimulation (SCS) by Hosobuchi (1986) and by Meglio et al. (1988) using the 133-Xenon wash-out technique. In this paper we report the effects of SCS on CBF as measured by two different techniques: 8 patients were studied with the 133-Xe method and 28 with the transcranial doppler sonography (TCD), in two cases both studies were performed. The aim of our study was to: 1-verify the effect of SCS on CBF, 2-compare observations made by two different methods, and 3-evaluate a possible correlation between the stimulated spinal segmental level and the modification of CBF. The results of our study confirm that SCS interacts with the mechanisms of regulation of CBF. The stimulation of different spinal cord levels in the same patient can produce different effects and such effects are reproducible. An increase of CBF is more likely to occur with the stimulation of the cervical spinal cord. In patients studied by both methods the sign of CBF changes induced by SCS was the same. Finally, in two patients the effect of SCS on CO2 autoregulation was studied with TCD. The results of such a study, although preliminary, suggest that CO2 and SCS have a competitive effect upon the mechanisms of regulation of CBF.

Spinal somatosensory evoked potential monitoring during microsurgery for syringomyelia: case reports

Spinal cord function was monitored during surgery in 2 cases of syringomyelia. The intraoperative recording of spinal segmental and conduction potentials evoked at cervical levels by the stimulation of median and tibial nerves were essential in the definition of the extent of the lesion and was consistent with postoperative neurological outcome.

Cerebral hemodynamics during spinal cord stimulation

An increase of cerebral blood flow (CBF) during spinal cord stimulation (SCS) has been shown in man using the 133Xenon inhalation technique. We report the effects of SCS on cerebral hemodynamics studied with transcranial Doppler sonography (TCD). Twenty-six patients with epidural electrodes implanted at the cervical level (11 patients) and at the thoracic level (15 patients) were investigated with recordings of CBF velocity in the middle cerebral arteries before and during SCS. Sixty-three and two-thirds percent of patients with cervical stimulation and 29.4% of patients with thoracic stimulation showed a decrease of cerebral vascular resistance simultaneously with an increase of the velocity of CBF.

Antinociceptive activity of intracerebroventricular lysine acetylsalicylate: an experimental study

We investigated the antinociceptive activity of Lysine Acetylsalicylate (LAS) after intracerebroventricular (icv) injection in experimental animals. The effect on tonic pain was studied by means of the Formalin test on 140 male Swiss mice. In a first group of animals icv LAS was injected at different doses (0.25-0.5-1 mg in saline solution 5 microliters). A second group received icv morphine 1 microgram in 5 microliters saline, and finally a third control group received icv 5 microliters saline. The effect of the compounds on the Formalin test was evaluated under blind conditions. Icv LAS had no effect on the nociceptive behaviour at doses of 0.25 and 0.5 mg, while a reduction of the licking time was evident after the injection of 1 mg of the drug. The time course and the degree of the analgesic effect of icv LAS was investigated and compared to the effect of icv morphine.

Microvascular decompression versus percutaneous procedures for typical trigeminal neuralgia: personal experience

This study includes 127 patients treated for typical trigeminal neuralgia, 74 of whom underwent a percutaneous microcompression (PMC), 33 a radiofrequency thermocoagulation (RFT) and 20 were explored for microvascular decompression (MVD). A mean follow-up of 24 months was reached by all the groups. Pain relief was evaluated as an 'all or none' effect. At hospital discharge, pain had disappeared in 93.2% of the patients treated with PMC, in 81.8% of those treated with RFT, and in 85% of the MVD group. At 24 months the effect was maintained by 57.2% of the PMC group, 57.6% of the RFT, and by 75% of the MVD group. Marked dysesthesia was reported by 6.7% of the patients treated with PMC, and by 24.2% of those who received a RFT. Impairment of masticatory function was observed in 10% of the PMC patients. Ipsilateral hypoacusia and transient IV nerve palsy in 1 patient was the only major complication after MVD.