We studied the microselective neurotomy (MSN) and its advantages to alleviate disabling spasticity. The best indication for MSN is focal spasticity. We performed 298 MSN, 87 nerves on the upper limb, 211 nerves on the lower limb) in 68 patients. The initial causes were: stroke, cranial trauma, postoperative complications and multiple sclerosis. MSN procedures were performed on the median nerve (n = 40) for wrist and finger flexion; musculo-cutaneus nerve (n = 38) for elbow flexion; ulnaris nerve (n = 9) for cubital deviation of the hand; gastrocnemius nerve (n = 98) and soleus nerve (n = 49) for equinus foot, tibial posterior nerve (n = 45) for varus foot, and fascicles (or bundles) of the flexor digitorum for “claw” toes (n = 19). The main preoperative test to identify the responsible nerve was a neuromuscular block with local anesthesia (lidocaine or bupivacaine) injected into the site of the nerve connecting the spastic muscle. During surgery, the identified nerve was exposed and its epineurium opened. Nerve bundles were teased apart into individual rootlets and a number of rootlets cut were previously planned, according to the spasticity. Follow-up was performed for up to 10 years, with a mean period of 29 months. Results demonstrated a reduction of limb spasticity of 2 to 3 points: modified Ashworth scale (MAS). Pain and clonus were also diminished in the affected limb. In some cases, voluntary movement was once again possible. MSN is a useful alternative in those cases of focal spasticity where physiotherapy and nerve block with botulinum toxin or phenol no longer produce satisfactory results.

In Parkinson’s disease (PD), dopaminergic neurons reduce the regulation of glutamatergic (glutamate-Glu) input from the cortex to neostriatum (caudate and putamen nuclei) consequently leading to a hyperactivity of globus pallidus internae (GPi) neurons that release gamma-amino-butyric acid (GABA) into the thalamic ventrolateral (VL) nucleus. The objective of the present experiment was to measure changes in GABA and Glu in the caudate and the thalamus of 2 patients during the application of electrical stimuli following either a pallidotomy or a thalamotomy. Proper insertion of the electrode was tested by applying high frequency electrical pulses (HFEP). During these procedures, we obtained neurochemical information placing cerebral (CMD) microdialysis probes in caudate nucleus and VL nucleus of ipsi- and contra-lateral thalamus. In VL thalamus, extracellular GABA decreased during HFEP, tending to reach previous levels once HFEP was finalized. Following the pallido- or thalamotomy GABA decreased again. Similarly, in the contralateral VL thalamus, extracellular GABA levels showed a similar but less pronounced profile but did not show any decrement after the lesion. Caudate Glu decreases when HFEP is applied to the GPi and recovers to previous levels after HFEP, but did not decrease again after lesion (GPi-tomy), instead it continued to rise. These results suggest that HFEP exerts a similar but reversible biochemical effect as thermopallido- or thermothalamotomy on GABA extracellular concentration in the ipsilateral VL thalamus. We also observe a distant effect of HFEP, but not of thermolesion, on contralateral thalamic GABA and ipsilateral caudate Glu.

Neurosurgery for psychiatric disorders, notably for obsessive-compulsive disorder (OCD), was initiated in Venezuela in the decade of 1970, and consisted since that time in the classic stereotactic anterior cingulotomy.In order to know further about the physiopathology of this disorder, we performed intracerebral microdialysis in 2 patients who were operated on.The aim was to measure changes in extracellular neurotransmitters within the basal ganglia.The microdialysis probes were stereotactically placed in the right caudate nucleus and in the dorsomedial nucleus of the right thalamus.The microdialysis was done before the left cingulotomy, during the pause and after the right cingulotomy.Glutamate and gamma-aminobutyric acid (GABA) changes were similar in the caudate nucleus of both patients, whereas in the dorsomedial nucleus the changes were opposite among the 2 patients.Although this study does not bring enough data to explain such differences yet, the existence of dynamic changes in the neurochemistry of the basal ganglia during cingulotomy shows that intracerebral microdialysis can help in the understanding of the pathophysiology of OCD and eventually in the design of new surgeries with better results.

Introducción: El microrregistro intracerebral durante la implantación de electrodos para la electromodulación cerebral profunda (EMCP) en la enfermedad de Parkinson ha sido motivo de debate a nivel mundial. La experiencia de nuestro grupo en cirugía del Parkinson se inició a finales de la década de 1960, se plasmó en el Primer Curso Latinoamericano de esta disciplina y se mantiene hasta nuestros días; comprende diferentes técnicas quirúrgicas que van desde la talamotomía ventrolateral y la palidotomía ventroposterolateral hasta la modalidad actual, la electromodulación cerebral profunda (EMCP) del núcleo subtalámico (NST). En este trabajo describimos una serie de 16 pacientes operados con esta técnica pero sin microrregistro. Técnica quirúrgica: Las coordenadas del NST se calculan por visualización directa en la resonancia magnética (RM) estereotáxica. Mediante control fluoroscópico verificamos si el instrumento se encuentra en el blanco matemático del sistema. En la cirugía, mediante un electrodo de rastreo se aplican impulsos eléctricos de alta (100 Hz) y baja (5 Hz) frecuencia en intensidad creciente (0,5-6,0 Voltios), desde 10 mm por encima del blanco hasta 5 mm por debajo del mismo. Un neurólogo evalúa el grado de mejoría clínica. Una vez localizado neurofisiológicamente el sitio deseado, se retira el electrodo de rastreo y se implantan los electrodos definitivos, los cuales se conectan al generador de impulsos. La parte operativa de la cirugía tiene una duración promedio de 4 horas. Resultados: De 16 pacientes operados, 3 fueron reintervenidos para recolocar el electrodo de un lado por mal posicionamiento, evidenciado por la TC posoperatoria y el estado clínico del paciente. Los pacientes presentaron una mejoría subjetiva de su estado general, según una escala visual analógica (EVA), del 55% en promedio al cabo de un año y una mejoría objetiva de la función motora, medida con la sección III de la UPDRS (Unified Parkinson’s Disease Rating Scale), del 41% al término del mismo período. Conclusión: En ausencia del microrregistro intracerebral, la técnica descrita se avizora como una alternativa viable con resultados plenamente aceptables. Es nuestra impresión de que el tiempo ahorrado por la ausencia del microrregistro permite una mejor tolerancia del paciente, con la consecuente mejor colaboración y obtención de mejores resultados clínicos.