Infra-Conus Single-Level Laminectomy for Selective Dorsal Rhizotomy: Technical Advance.

BACKGROUND/AIMS: Selective dorsal rhizotomy for spastic cerebral palsy is an effective and well-validated surgical approach. Multiple techniques have been described in the past including multiple laminectomies and a single-level laminectomy at the level of the conus. There is considerable technical challenge involved with a single-level laminectomy approach. METHODS: We report here a modification of the single-level laminectomy that selectively analyzes each individual nerve root with electromyography to separate dorsal and ventral nerve roots through comparison of stimulus responses. RESULTS: In 18 children with cerebral palsy who underwent this operation there was a mean improvement in the Modified Ashworth Scale of 2.0 with no reported incidence of muscle weakness, sensory loss, or neurogenic bladder. CONCLUSION: This approach allows for a modification of selective dorsal rhizotomy through a single-level laminectomy and tailors the selection of nerve root sectioning to the individual patient of interest while still maintaining its effectiveness.

The science of conventional and water-cooled monopolar lumbar radiofrequency rhizotomy: an electrical engineering point of view.

Radiofrequency ablation (RFA) is a safe and effective pain therapy used to create sensory dysfunction in appropriate nerves via thermal damage. While commonly viewed as a simple process, RF heating is actually quite complex from an electrical engineering standpoint, and it is difficult for the non-electrical engineer to achieve a thorough understanding of the events that occur. RFA is highly influenced by the configuration and properties of the peri-electrode tissues. To rationally discuss the science of RFA requires that examples be procedure-specific, and lumbar RFA is the procedure selected for this review. Adequate heating of the lumbar medial branch has many potential failure points, and the underlying science is discussed with recommendations to reduce the frequency of failure in heating target tissues. Important technical details of the procedure that are not generally appreciated are discussed, and the status quo is challenged on several aspects of accepted technique. The rationale underlying electrode placement and the limitations of RF heating are, for the most part, commonly misunderstood, and there may even need to be significant changes in how lumbar radiofrequency rhizotomy (RFR) is performed. A new paradigm for heating target tissue may be of value. Foremost in developing best practices for this procedure is avoiding pitfalls. Good RF heating and medial branch lesioning are the rewards for understanding how the process functions, attention to detail, and meticulous attention to electrode positioning.

Rizotomía sacra percutánea por radiofrecuencia en el tratamiento de la hiperactividad del detrusor neurogénico en pacientes con lesiones de la médula espinal / Percutaneous radiofrequency sacral rhizotomy in the treatment of neurogenic detrusor overactivity in spinal cord injured patients

Objetivo: Evaluar los efectos de la rizotomía sacral percutánea por radiofrecuencia en pacientes con lesión de la médula espinal sobre parámetros urodinámicos (capacidad cistométrica máxima [CCM] y presión del detrusor a capacidad cistométrica máxima [PdetCCM]). Material y Métodos: En este estudio prospectivo se evaluó a 8 pacientes con LME (4 hombres y 4 mujeres) con una media de edad de 31,3 años (de 22 a 41). El intervalo medio entre la lesión de la médula espinal y la rizotomía fue de 53,5 meses (entre 20 y 96). A todos los pacientes se les practicó un bloqueo anestésico bajo control fluoroscópico de la tercera raíz sacral de forma bilateral con bupivacaína 0,5%. Se eligió para rizotomía sacral percutánea por radiofrecuencia a los que respondieron con un aumento en la capacidad vesical. Se procedió a la evaluación urodinámica de todos los pacientes a los 6 y los 12 meses tras la realización del procedimiento. Se consignaron tanto la CCM como la PdetCCM. Resultados: Todos los pacientes mostraron una mejora significativa en la CCM a los 12 meses. El volumen vesical medio aumentó de los 100,2±57,1 a 282,9±133,4 ml (p < 0,05). La PdetCCM se redujo de 82,4±31,7 a 69,9±28,7 cm H2O (p = 0,2). Tres pacientes con disreflexia autonómica experimentaron un alivio total de los síntomas tras el procedimiento. A los 12 meses se observó una reaparición de la hiperactividad del detrusor en todos los pacientes. Un paciente presentó abolición de las erecciones reflejas tras el procedimiento. No se observaron complicaciones de importancia en relación con la rizotomía. Conclusiones: La rizotomía sacral percutánea por radiofrecuencia es una técnica mínimamente invasiva, de baja morbilidad, que puede aumentar la CCM. Existe una tendencia hacia la reducción de la PdetCCM en pacientes con LME a los 12 meses, a pesar de que no se alcanza un nivel estadísticamente significativo (AU)

Introduction: To evaluate the effects of percutaneous radiofrequency sacral rhizotomy in spinal cord injured (SCI) patients on urodynamic parameters (maximum cystometric capacity — MCC and detrusor pressure at maximum cystometric capacity - PdetMCC). Material and Methods: This prospective study assessed eight patients with SCI (four men and four women) with a mean age of 31.3 years (22 to 41). Mean interval period between spinal cord lesion and rhizotomy was 53.5 months (20 to 96). All patients underwent an anesthetic block of the 3rd sacral root bilaterally using 0.5% bupivacaine under fluoroscopic control. Those who responded with an increase on bladder capacity were selected to undergo the percutaneous radiofrequency sacral rhizotomy. All patients underwent urodynamic evaluation at 6 and 12months following the procedure. MCC and PdetMCC were recorded. Results: All patients presented a significant improvement on MCC after 12 months. The mean vesical volume increased from 100.2±57.1 to 282.9±133.4 ml (p<0.05). The PdetMCC reduced from 82.4±31.7 to 69.9±28.7 cmH2O (p = 0.2). Three patients with autonomic dysreflexia had complete relief of symptoms after the procedure. At 12 months, recurrence of detrusor hyperactivity was observed in all patients. One patient presented abolishment of reflex erections after the procedure. No major complications related to the rhizotomy were noted.C onclusions: Percutaneous radiofrequency sacral rhizotomy is a minimally invasive technique with low morbidity able to increase MCC. There is a trend towards the reduction of the PdetMCC in SCI patients at 12 months, although statistical significance was not reached (AU)

Foramen ovale cannulation guided by intra-operative computed tomography with integrated neuronavigation for the treatment of trigeminal neuralgia.

BACKGROUND: Radiofrequency rhizotomy of the Gasserian ganglion for the treatment of trigeminal neuralgia via percutaneous cannulation of the foramen ovale is facilitated by various localization modalities. In our preliminary study, we described the feasibility of computed tomography (CT) using an integrated neuronavigation system to cannulate the foramen ovale. METHODS: Analysis was performed on 42 consecutive patients who underwent cannulation of the foramen ovale for radiofrequency trigeminal rhizotomy guided by CT using an integrated neuronavigation system. The reproducibility and safety of the neuronavigation-guided procedure were evaluated. RESULTS: Overall, the average dimension of the foramen ovale was 7.1 (1.5) × 4.7 (1.1) mm, and it was successfully cannulated by neuronavigation guidance in 31 (73.8%) patients with a mean cannulation time of 3.1 (0.7) min and an overall procedure time of 68.2 (16.4) min. The remaining 11 (26.2%) patients required subsequent CT guidance for successful puncture of the foramen ovale. CONCLUSIONS: These data demonstrate that neuronavigation-guided cannulation of the foramen ovale can be executed both quickly and safely on an outpatient basis. Additionally, the use of CT with integrated neuronavigation technology provides superior visual-spatial information compared to conventional fluoroscopy, the process of CT scanning, object planning, and neuronavigation-guided intervention can be completed in the same locale, and its application is easy to master and has the potential to enhance procedure tolerability of awake patients.

Laser-guided lumbar medial branch kryorhizotomy.

The authors describe a modification of the medial branch kryorhizotomy technique for the treatment of lumbar facet joint syndrome using a fluoroscopy-based laser-guided method. A total of 32 patients suffering from lumbar facet joint syndrome confirmed by positive medial nerve block underwent conventional or laser-guided kryorhizotomy. The procedural time (20.6 +/- 1.0 vs 16.3 +/- 0.9 minutes, p < 0.01), fluoroscopy time (54.1 +/- 3.5 vs 28.2 +/- 2.4 seconds, p < 0.01), radiation dose (407.5 +/- 32.0 vs 224.1 +/- 20.3 cGy/cm(2), p < 0.01), and patient discomfort during the procedure (7.1 +/- 0.4 vs 5.2 +/- 0.4 on the visual analog scale, p < 0.01) were significantly reduced in the laser-guided group. There was a tendency for a better positioning accuracy when the laser guidance method was used (3.0 +/- 0.3 vs 2.2 +/- 0.3 mm of deviation from the target points, p > 0.05). No difference in the outcome was observed between the 2 groups of patients (visual analog scale score 3.5 +/- 0.2 vs 3.3 +/- 0.3, p > 0.05). This improved minimally invasive surgical technique offers advantages to conventional fluoroscopy-based kryorhizotomy.

Anatomic study of the infraorbital foramen for radiofrequency neurotomy of the infraorbital nerve.

OBJECTIVE: To examine the anatomy of the infraorbital canal and foramen and the angles at which a radiofrequency probe must be directed to enter the infraorbital foramen and canal, as a guide to performing radiofrequency ablation of the infraorbital nerve in patients with relative or absolute contraindications to lesions of the trigeminal ganglion or posterior root. METHODS: Eleven cadaveric skulls were studied. The infraorbital nerve, after passing through the infraorbital foramen, enters the infraorbital canal and groove in the floor of the orbit before reaching the foramen rotundum. Small probes were placed through the foramen into the infraorbital canal, and pictures were taken in the anteroposterior and sagittal planes. The pictures were analyzed using the ImageTool program (University of Texas Health Science Center, San Antonio, TX) to calculate the anteroposterior and sagittal angles of the probe. The distances of the foramen from the midline, lateral edge of the anterior nasal aperture, and inferior orbital rim were examined. RESULTS: A probe introduced through the cheek from below and medial to the foramen and directed upward and laterally at an angle of approximately 22 degrees in the coronal plane and 120 degrees in the sagittal plane toward a point approximately 26 mm from the midline and 8 mm below the inferior orbital rim will penetrate the infraorbital foramen for placement of the probe's tip in the infraorbital canal. CONCLUSION: The coordinates for placement of the radiofrequency probe through the infraorbital foramen and into the infraorbital canal are reviewed, along with a discussion of pitfalls in radiofrequency ablation of the nerve.

Endosurgical repair of an iatrogenic facial arteriovenous fistula due to percutaneous trigeminal balloon rhizotomy.

A 56-year-old woman with right-sided trigeminal neuralgia (TN), who underwent technically uneventful percutaneous balloon rhizotomy, developed significant bilateral pulsatile tinnitus on the first post-operative day. Although the patient reported significantly improved neuralgia, auscultation revealed a right facial bruit. Magnetic resonance angiography (MRA) of the face and brain demonstrated prominent right facial and jugular venous vascularity. Catheter angiography confirmed the suspected facial arteriovenous fistula (AVF). A transarterial approach was used to explore the AVF which arose from a laceration of the right internal maxillary artery and which fistulized directly with the pterygoid venous plexus. Endosurgical repair utilizing three non-fibered platinum coils was done under conscious sedation at the same setting as the diagnostic angiogram. Angiographically, the fistula was obliterated, and the patient's bruit and tinnitus immediately resolved. Follow-up MRA at 3.5 months was normal, and, the patient had no clinical symptoms of recurrent AVF. In conclusion facial AVF can complicate percutaneous trigeminal rhizotomy. Iatrogenic facial AVF can be repaired via an endovascular approach.

The efficacy of a two needle electrode technique in percutaneous radiofrequency rhizotomy:An investigational laboratory study in an animal model.

BACKGROUND: Radiofrequency neurotomies are used to help reduce pain caused by structures innervated by the medial branch of the dorsal spinal nerve. The duration of effect may vary proportionally to the length of nerve coagulated. Techniques used to maximize the length of nerve within the radius of maximal heat include making multiple lesions, using larger needles, positioning the exposed needle parallel to the target nerve, and attempting more precise placement using 50 hertz test stimulation. A variation of the technique uses two needles that are simultaneously placed to lie parallel to one another and parallel to the probable area the target nerve is known to traverse. Heating both needles at the same time would be a faster method that theoretically might also include more tissue within the heating radius of the needle lengths. OBJECTIVE: The purpose of this study was to confirm that two parallel radiofrequency lesions increased the volume of tissue included within the heating radius of the exposed needle tips, to determine optimal heating parameters, and to establish how far apart the needles can be placed and still achieve temperatures between the needles that will coagulate nerves. STUDY DESIGN: Investigational laboratory study in an animal model. METHODS: Ex-vivo porcine spinal tissue samples were prepared following a standardized protocol and two needle electrodes were connected to the Stryker rhizotomy device. A series of tissue samples were prepared with the needles placed 1, 1.5, 2, 3, 4, 5, 6, 7, 8, or 9 mm apart in respective samples. The needles were positioned parallel to the surface, and perpendicular to the tissue. In one series of samples, two needle electrodes were heated sequentially for each needle placement. Temperature parameters ranged from 60 to 100 degrees C and the time duration ranged from 60 to 90 seconds for each electrode. After each heating, all tissue was dissected and the size of the coagulated area measured. Temperatures at the midpoint between the two needle electrodes were monitored and measured with a Radionics needle sensor. Using the same study protocol and evaluation, a second set of samples was studied but both needle electrodes were heated simultaneously. RESULTS: Maximal lesion size was observed when the temperature of the electrode was higher than 70-80 degrees C and maintained for longer than 70 seconds. When the needles were heated sequentially, the needles could be placed no further than 1.5 to 2 mm apart before areas of incomplete coagulation were visualized at the midpoint between the needles. When both needles were simultaneously heated the needles could be placed 4 mm apart before incomplete coagulation was visualized. With simultaneous heating, the highest peak temperature of the midpoint between two needles (6 mm apart) exceeded 66 degrees C, compared to a temperature of 40 degrees C achieved with sequential heating. CONCLUSIONS: This research confirms the efficacy of utilizing two needle electrodes during lumbar facet rhizotomy in an experimental model. Heating the two electrodes sequentially appears to coagulate a wider area and thus would be more likely to include a longer length of the target nerve and thus potentially could achieve better results in less time.

Right ventricular outflow tract transannular patch placement without cardiopulmonary bypass.

In children with pulmonary atresia not amenable to initial complete correction, antegrade pulmonary blood flow can be established with surgical right ventricular outflow tract (RVOT) patch enlargement. An 11-year experience with RVOT transannular patch (TAP) augmentation without the use of cardiopulmonary bypass (off-pump) is reported. From March 1993 to October 2004, off-pump surgical RVOT enlargement with a TAP was attempted in all patients in whom a concurrent procedure that required bypass was not required. The procedure was performed with cardiopulmonary bypass standby. Twenty-two consecutive patients in whom this procedure was attempted were reviewed. Twenty of 22 patients tolerated off-pump TAP placement. In 2 patients with ductal-dependent pulmonary blood flow, off-pump TAP placement was not tolerated. Adequate antegrade pulmonary blood flow was achieved in all patients without operative mortalities or complications. There was one death in the postoperative period from myocardial ischemia secondary to right ventricular-dependent coronary circulation. Transannular RVOT patch augmentation can be performed safely and effectively without cardiopulmonary bypass.

Percutaneous trigeminal nerve radiofrequency rhizotomy guided by computerized tomography fluoroscopy. Technical note.

The authors describe a new procedure for percutaneous trigeminal radiofrequency rhizotomy. Computerized tomography fluoroscopy is used for guidance of the rhizotomy needle insertion through the foramen ovale. Ten patients were treated using this method, and in each case the target was reached with a single puncture. The potential benefits of this method are presented.

[Surgery in the dorsal root entry zone for treatment of chronic pain]. / Chirurgie au niveau de la zone d'entrée des racines dorsales dans la moelle (dorsal root entry zone) pour le traitement des douleurs chroniques.

Microsurgical drezotomy (MDT) consists of an incision and bipolar coagulations performed ventro-laterally in the Dorsal Root Entry Zone (DREZ) at the entrance of the rootlets into the dorso-lateral sulcus. The lesion is directed at 35 ventro-medially, and to 2-3 mm deep according to the pre-operative neurological status and the desired effects. MDT i) interrupts the small (nociceptive) fibres regrouped laterally and the large (myotatic) afferents which runs centrally, whilst sparing part of the large medial (lemniscal) fibres, ii) destroys the (excitatory) medial part of the Lissauer's tract, iii) and the cells of the dorsalmost layers of the dorsal horn, which can be the site of hyperactivity, as we were able to record in patients with deafferentation pain. Best indications are: i) well-localized cancer pain, such as Pancoast syndrome; ii) neuropathic pain due to: brachial plexus injuries; cauda equina and/or spinal cord lesions (especially for pain corresponding to segmental lesions); peripheral nerve injuries, amputation, herpes zoster - especially when the predominant component of pain is of the paroxysmal type and/or corresponds to provoked hyperalgesia/allodynia); iii) excess of spasticity, especially when associated with severe pain.

[Transcutaneous radiofrequency destruction of the articular nerves in treating low back pains]. / Chreskozhnaia radiochastotnaia destruktsiia sustavnykh nervov v lechenii nizhnepoiasnichnykh bolei.

Lumbar pain is a most common suffering which frequently becomes chronic. In the mechanical low back syndrome caused by an abnormality in the intervertebral joints, lumbar pain may be rather easily differentiated from pain induced by to spinal root compression due to discal hernia or intervertebral foramen stenosis. The absence of benefits from conservative treatment of lumbar pain caused by intervertebral joint abnormalities is an indication for the highly effective and low-traumatic surgical technique transcutaneous radiofrequency destruction of intervertebral facette nerves. The technique yields good results in small displacements of the lumbar vertebra which cannot undergo orthopedic interventions, as well as in severe vertebral deformities which cause a higher load on the intervertebral joints.

Percutaneous radiofrequency rhizotomy of lumbar spinal facets: the results of 46 cases.

The results of percutaneous radiofrequency rhizotomy of lumbar spinal facets in 46 patients followed at least three months (mean 15 months) are reported and compared with those reported previously. Satisfactory pain relief three months after the procedure was achieved in 36.4 percent of patients without operations and in 41.7 percent of patients, with operations other than fusion. No patient had previously undergone fusion. Treatment of low-back pain by using radio-frequency thermocoagulation of spinal facets is a simple, safe, and well-tolerated procedure. It can be used to relief of pain in spite of decreasing rates of success within the follow-up period.

Variation between centers in electrophysiologic techniques used in lumbosacral selective dorsal rhizotomy for spastic cerebral palsy.

The extent of variation between centers in the electrophysiologic techniques used in lumbosacral selective dorsal rhizotomy (SDR) for spastic cerebral palsy was studied using a questionnaire survey. Nineteen centers completed the questionnaire, and the responses were analyzed for those 16 centers in which the extent of dorsal root section was guided by intraoperative electrophysiologic responses. Consistent techniques included: use of unipolar stimulating electrodes (11 of 15 responses); stimulation < 4 cm from the root exit foramen (14 of 16); separation of dorsal roots into three to eight rootlets each (14 of 16); tetanic stimulation frequency of 50 Hz (11 of 16); tetanic stimulation at 100% of threshold (13 of 16); recording from multiple lower limb muscles simultaneously (16 of 16), and using contralateral spread of the response as a major criterion of electrophysiologic abnormality (13 of 16). There was more variation (< 11 of 16 concurrence) with respect to the use of a constant current versus constant voltage stimulator; the location of the cathode of the stimulating electrode relative to the anode; the definition of the threshold for a response; whether threshold was determined from stimulation of a dorsal root, or individual rootlets; the type of recording electrodes (needle versus surface), and the relative importance of electrophysiologic versus clinical findings in determining how much of each dorsal root to cut. In 10 centers, SDR would proceed without the benefit of electrophysiologic guidance if the equipment should fail intraoperatively (only if quadriplegic in 4), and this had happened in 6. The results indicate significant variation in many aspects of electrophysiologically guided SDR.

Intraoperative mapping of the trigeminal nerve root: technique and application in the surgical management of facial pain.

A method for intraoperative topographic mapping of the trigeminal nerve root using electrophysiological methods is described. A series of 15 patients under general anesthesia during microvascular decompression and selective posterior fossa trigeminal rhizotomy was studied. This method was used to study the localization of fibers of individual subdivisions of the intradural portion of the trigeminal nerve and as a guide for performing physiologically controlled, selective, microsurgical trigeminal rhizotomy.

[Surgical treatment of migrainous neuralgia]. / Khirurgicheskoe lechenie migrenoznoi nevralgii.

The paper gives the results of surgical management in 18 patients with migrainous neuralgia who underwent 20 surgical interventions. High-frequency transcutaneous trigeminal rhizotomy eliminated pain in 2 of 6 patients. Microsurgical radicular exploration of the trigeminal nerve (1 case) and the intermediate facial nerve (2 cases) revealed no vascular compression of nerve fibers. Vertical ultrasonic destructions of the trigeminal caudal subnucleus and the descending upper spinal segment CII tract in 12 patients. The upper border of nucleotractomy varied from the obex level of the fourth ventricle to as long as 5 mm below. Complete removal of migrainous neuralgia was achieved in 11 patients followed for 12-81 months and in 1 patient with recurrent facial pain successfully treated with repeated trigeminal nucleotractotomy. Sensory sequelae of destruction and somatotopic organization of the trigeminal caudal subnucleus are also dealt with in the paper.