-The present study, the largest in the literature, was performed to assess the effectiveness and safety of unilateral subthalamic nucleus (STN) lesioning for Parkinson's disease (PD). From August 1999 to September 2000, 21 consecutive patients evaluated pre-and postoperatively by a single examiner were operated. Levodopa intake and dyskinesia, Hoehn & Yahr, Schwab & England and UPDRS motor scores were recorded. Stereotactic CT and MRI and the effects of macrostimulation were used to determine STN coordinates. A single radiofrequency lesion was made (60-75ºC/60"). Concomitant ipsilateral Vim/VOp lesions were made in 8 patients. Using a new technique, we were able to determine the territory of STN involved by the surgical lesion. The Wilcoxon and Mann-Whitney statistical tests were applied to evaluate the surgical results. All recorded parameters showed stable improvement after a mean follow up of 13.5 months. Recurrence occurred in two patients. Contralateral tremor arrest and decrease of rigidity and bradykinesia should be regarded as STN hallmarks to stimulation. Hyperintense lesions in the early-phase MRI seem to be a poor prognostic factor. Lateral territory lesioning correlates with better results. There was no significant difference between the cohorts with and without a Vim/VOp lesion. Dyskinesias happened in two patients (promptly abolished by a Vim/VOp lesion). Other complications were transient and/or rare. In conclusion, STN lesioning is a safe and very effective procedure to treat PD and probably an underutilized operation for those who can not afford the costs of DBS.KEY WORDS: subthalamic nucleus lesioning, deep brain stimulation, stereotactic surgery, subthalamic nucleotomy, subthalamotomy, Parkinson's disease. Lesão unilateral do núcleo subtalâmico: um tratamento seguro e eficaz para a doença de ParkinsonRESUMO -O presente estudo, o maior da literatura, foi realizado para avaliar a eficácia e segurança da lesão unilateral do NST (núcleo subtalâmico) para o tratamento da DP (doença de Parkinson). Entre agosto de 1999 e setembro de 2000, 21 pacientes consecutivos avaliados pré e pós-operatoriamente por um único examinador foram operados. Os seguintes parâmetros foram avaliados: dose diária de levodopa, discinesia induzida pela levodopa, estadiamento da doença, atividades de vida diária e escores motores da UPDRS. RNM e TC estereotáxicas e os efeitos da estimulação com macroeletrodo foram utilizados na determinação das coordenadas do NST. Uma única lesão por radiofrequência foi realizada (60 -75ºC / 60"). Lesão concomitante de Vim/VOp ipsilateral foi realizada em 8 pacientes. Utilizando-se uma nova técnica, foi possível estabelecer o território do NST lesado cirurgicamente. Os testes estatísticos de Wilcoxon e Mann-Whitney foram aplicados para avaliar os resultados cirúrgicos. Todos os parâmetros avaliados apresentaram melhora sustentada após seguimento médio de 13.5 meses. Recidiva ocorreu em 2 casos. Abolição do tremor e redução da rigidez e bradicinesia contralaterais devem ser considerad...

No abstract

Paresthesia-producing (PP), but not periventricular grey (PVG) deep brain stimulation (DBS) proved effective in steady neuropathic pain in 25 patients receiving both, regardless of the PP site stimulated, but PVG-DBS suppressed allodynia or hyperpathia in 3 cases of stroke-induced pain. In patients with stroke-induced central pain, PP-DBS was unpleasant in 6 of 17 (35%), all with allodynia and/or hyperpathia, but not in patients with spinal cord central or peripheral neuropathic pain with allodynia or hyperpathia. Of 11 patients in whom prior ineffective dorsal column stimulation (DCS) produced appropriate paresthesia, none responded to PP-DBS; 5 of 7 did so in whom DCS produced no paresthesia or relieved pain. Periaqueductal grey DBS was nearly always unpleasant, PVG-DBS sometimes was.

The region of the pedunculopontine tegmental nucleus (PPTg) has been proposed as a novel target for deep brain stimulation (DBS) to treat levodopa resistant symptoms in motor disorders. Recently, the anatomical organization of the brainstem has been revised and four new distinct structures have been represented in the ventrolateral pontine tegmentum area in which the PPTg was previously identified. Given this anatomical reassessment, and considering the increasing of our experience, in this paper we revisit the value of DBS applied to that area. The reappraisal of clinical outcomes in the light of this revisitation may also help to understand the consequences of DBS applied to structures located in the ventrolateral pontine tegmentum, apart from the PPTg. The implantation of 39 leads in 32 patients suffering from Parkinson's disease (PD, 27 patients) and progressive supranuclear palsy (PSP, four patients) allowed us to reach two major conclusions. The first is that the results of the advancement of our technique in brainstem DBS matches the revision of brainstem anatomy. The second is that anatomical and functional aspects of our findings may help to explain how DBS acts when applied in the brainstem and to identify the differences when it is applied either in the brainstem or in the subthalamic nucleus. Finally, in this paper we discuss how the loss of neurons in brainstem nuclei occurring in both PD and PSP, the results of intraoperative recording of somatosensory evoked potentials, and the improvement of postural control during DBS point toward the potential role of ascending sensory pathways and/or other structures in mediating the effects of DBS applied in the ventrolateral pontine tegmentum region.

SUMMARY -Despite its use for a long time, the way thalamic ventrobasal (VB) stimulation acts to produce pain relief is still unknown. One of the most accepted hypotheses, sponsored by Tsubokawa among others, proposes that VB stimulation excites raphespinal and reticulospinal neurons of the rostroventral medulla which in turn send respectively inhibitory serotonergic and noradrenergic axons through both dorsolateral funiculi (DLF) to the dorsal horn ( DH) nociceptive neurons; this pathway would be the same as is involved in periventricular-periaqueductal gray (PVG-PAG) stimulation induced inhibition of DH nociceptive neurons. This hypothesis implicates the necessity of DLF intactness; in fact, it was showed that section of bilateral DLF inhibits the response of DH nociceptive neurons to VB stimulation. If the above mentioned hypothesis is correct, one could expect that unilateral VB stimulation would produce bilateral pain relief, VB and PVG stimulation would be useful for treating the same modalities of pain and that in patients with central cord-based pain harboring complete cord transection, VB stimulation would not work at all. In order to check these possibilities, the patiens with central cord-based pain admitted to the Division of Neurosurgery, Toronto Hospital between June 1978 and July 1991 to undergo deep brain stimulation (DBS) were reviewed. Sixteen patients were operated on. Based on clinical criteria, four out of these sixteen patients were thought to present complet cord transection (all four were men, with an average age of 48 years and pain secondary to cord injury). The effectiveness of the procedure was evaluated in this subset of patients: 75% of them enjoyed excellent pain relief with VB stimulation; PVG stimulation, however, performed in three out of these four patients, did not produce pain relief. Besides, our clinical experience has demonstrated that VB stimulation is effective in treating only contralateral pain.These results, as well as certain experimental data provided by a review of the literature, seem to provide evidence enough to contest Tsubokawa's hypothesis.KEY WORDS: pain, analgesia, electrical stimulation therapy, thalamic nuclei, thalamus, stereotaxis. V i a s e n v o l v i d a s n o a l í v i o d a d o r p e l a e s t i m u l a ç ã o t a l â m i c a v e n t r o b a s a l : e v i d ê n c i a c o n t r a a h i p ó t e s e e s t i m u l a ç ã o v e n t r o b a s a l -> e x c i t a ç ã o d o b u l b o r o s t r o v e n t r a l -> i n i b i ç ã o d o c o r n o d o r s a lRESUMO -A despeito de seu uso há longo tempo, a maneira pela qual a estimulação talâmica ventrobasal (VB) produz alívio da dor é ainda desconhecida. Segundo uma das hipóteses mais aceitas, defendida por Tsubokawa dentre outros, a estimulação de VB excita neurônios rafe-espinhais e reticulo-espinhais do bulbo rostroventral, os quais por sua vez emitem respectivamente axônios serotoninérgicos e noradrenérgicos inibitórios para os neurônios nociceptivos de ambos os cornos dorsais através dos funículos dorsolaterais...

Surgical treatment of intractable visceral pain has always been a challenge. The relatively recent discovery of a specific visceral pain pathway brought a new insight to this matter. The authors describe a new technique to interrupt this pathway, the CT-guided percutaneous punctate midline myelotomy, successfully applied in two patients with intractable pelvic visceral pain. Due to its simplicity, safety and high effectiveness, it may become the treatment of choice for intractable visceral pain.

SUMMARY -Thalamic ventrobasal (VB) stimulation, first performed by Mazars, in 1961, is a valuable means for treating central and deafferentation pain. The way it acts to achieve pain relief, however, is still a matter of controversy. In this paper, the author examines previously proposed hypotheses and suggests that VB stimulation induces pain relief by activation of a multisynaptyic inhibitory pathway to the medial thalamus, in which the dopaminergic nigrostriatal system exerts an important role and by modulation of abnormal activity in VB itself. The multisynaptic pathway involved, as well as the neurotransmitters, are suggested: VB stimulation excites somatosensory cortex through the glutaminergic thalamocortical pathway, which in turn, sends excitatory glutaminergic axons to the motor cortex. The sensorymotor cortex originates the excitatory glutaminergic corticostriatal pathway to the anterior putamen. The anterior putamen sends excitatory peptidergic (substance P) pathways to the globus pallidus interims (striatopallidal pathway) and to the substantia nigra reticulata (striatonigral pathway). The globus pallidus interims inhibits the medial thalamus through the pallidothalamic GABAergic pathway. The substantia nigra reticulata sends inhibitory GABAergic projections to the medial thalamus (nigrothalamic pathway) and excites the substantia nigra compacta. The substantia nigra compacta projects excitatory dopaminergic axons to the striatal neurons (nigrostriatal pathway) with output to the globus pallidus internus and substantia nigra reticulata and so on. Data to support this hypothesis are provided by an extensive review of the literature.KEY WORDS: pain, analgesia, electrical stimulation, thalamic nuclei, thalamus, cerebral cortex, basal ganglia, neurotransmitters. Estimulação talâmica ventrobasal para alívio da dor: prováveis mecanismos, vias e neurotransmissoresRESUMO -A estimulação talâmica ventrobasal (VB), primeiramente realizada por Mazars em 1961, é método útil para o tratamento de dor central e dor de deaferentação. A maneira como ela atua para produzir alívio da dor, porém, é ainda questão de controvérsia. Neste estudo, o autor examina as hipóteses anteriormente propostas e sugere que o alívio da dor obtido pela estimulação de VB se deve a dois prováveis mecanismos: (1) Modulação da atividade anormal em VB e (2) Ativação de uma via multisináptica inibitória para os neurônios nociceptives do tálamo medial, na qual o sistema dopaminérgico nigroestriatal exerce importante papel. A via multisináptica envolvida, bem como os neurotransmissores, são sugeridos: a estimulação de VB, através da via tálamo-cortical glutaminérgica, excitaria o córtex somatosensitivo que, por sua vez, excitaria o córtex motor através dos neurotransmissores excitatórios glutamato e aspartate. No córtex sensitivo-motor se originaria a via corticoestriatal glutaminérgica excitatória para o putâmen anterior, o qual emitiria uma via peptidérgica (substância P) excitatória para o globo pálido interno (via estriatopalidal) e para a s...

-Objectives: The pioneering performance of gamma probe-assisted surgery (GPAS) for brain tumors, aiming not only an improvement of tumor detection, but mainly assurance of its complete removal and the study of the usual distribution of the 99m Tc-MIBI in the brain SPECT of normal individuals. Method: Patient's informed consent and demonstration of the tumor by the preoperative MIBI SPECT were the inclusion criteria adopted for GPAS, which was performed in one patient with a right parietal lobe metastatic tumor. The radiotracer ( 99m Tc-MIBI) was injected in a peripheral vein 5 hours before the operation. A tumor to-normal tissue count ratio equal to or greater than 2/1 was considered indicative of tumor. MIBI SPECT was performed in five normal individuals in a pilot study. Results: The gamma probe greatly facilitated intraoperative tumor detection (tumor to-normal brain count ratio was 5/1) and indicated a small piece of residual tumor after what was thought to be a complete tumor removal, allowing its resection, which, otherwise, would have been left behind. Postoperative CT confirmed complete tumor resection. The MIBI SPECT in normal individuals showed an increased uptake by the hypophisis, choroid plexus, skull, scalp and salivary glands and absence of uptake by the normal brain tissue. There were no complications. Conclusion: GPAS proved to be, in this single case, a safe and reliable technique to improve brain tumor detection and to confirm the presence or absence of residual tumor.KEY WORDS: radioguided surgery, gamma probe, gamma probe-assisted surgery, 99m Tc-MIBI, SPECT, brain tumor, brain neoplasm.Ressecção microcirúrgica de tumor cerebral assistida por detector gama: uma nova técnica RESUMO -Objetivos: A realização pioneira de cirurgia assistida por detector gama (CADG) para tumores cerebrais, objetivando-se não apenas a identificação do tumor, mas, sobretudo, assegurar-se quanto à sua completa ressecção e estudar a distribuição usual do 99m Tc-MIBI no SPECT cerebral de indivíduos normais. Método: O consentimento informado do paciente e a demonstração do tumor pelo SPECT pré-operatório com MIBI foram os critérios de inclusão adotados para a CADG, a qual foi realizada em um paciente com metástase para lobo parietal direito. O radiotraçador ( 99m Tc-MIBI) foi injetado em uma veia periférica 5 horas antes da cirurgia. Uma relação ≥ 2/1 entre a radiação gama emitida pelo tumor e pelo tecido normal foi considerada como indicativa de presença tumoral. Em um estudo piloto, SPECT cerebral com MIBI foi realizado em cinco pacientes normais. Resultados: O detector gama em muito facilitou a detecção per-operatória do tumor e demonstrou a presença de um pequeno resíduo tumoral após o que se pensou tratar-se de uma completa ressecção; tal resíduo, de outro modo, não teria sido percebido, o que teria impossibilitado sua exérese. Tomografia computorizada pós-operatória confirmou a completa ressecção do tumor. O SPECT com MIBI de indivíduos normais mostrou sua captação pela hipófise, plexo coróide, crânio, co...