Subarachnoid Catheter Research Articles

Technical guideline for intra-prepontine cisternal drug delivery via spinal puncture through subarachnoid catheterization.

The distribution characteristics of intrathecal drugs and the limitation of current catheterization techniques make traditional intrathecal analgesic treatment nearly useless for refractory craniofacial pain, such as trigemina neuralgia. This technical guideline aims to promote the widespread and standardize the application of intra-prepontine cisternal drug delivery via spinal puncture and catheterization. A modified Delphi approach was used to work for this guideline. On the issues related to the intra-prepontine cisternal targeted drug delivery technique, the working group consulted 10 experts from the field with 3 rounds of email feedback and 3 rounds of conference discussion. For the efficacy and safety of the intra-prepontine cisternal targeted drug delivery technique, a consensus was formed on 7 topics (with an agreement rate of more than 80%), including the principles of the technique, indications and contraindications, patient preparation, surgical specifications for intra-prepontine cisternal catheter placement, analgesic dosage coordination, analgesic management, and prevention and treatment of complications. Utilizing the intra-prepontine cisternal drug infusion system to manage refractory craniofacial pain could provide advantages in terms of minimally invasive, secure, and effective treatment. This application can not only alleviate the suffering of individuals experiencing the prolonged pain but also support the maintenance of quality of life and dignity in their final moments, justifiing its widespread dissemination and standardized adoption in domestic and international professional fields.

THE ANESTHETIC MANAGEMENT OF EXTENSIVE AORTIC THORACIC ANEURYSM REPAIR WITH CLAMSHELL INCISION

Introduction Surgical repair of extensive thoracic aorta disease represents an interesting challenge, both surgical and anesthetic. We describe the surgical repair of an acute aortic dissection beginning in the aortic arch in relation with aortic coartation and a post coartation aneurism, and the aspects related to planning, management and perioperative care. The clamshell incision is associated with respiratory complications, bleeding and post-operative severe pain. Interruption of spinal cord blood supply is one of the causes of spinal cord injury after thoracic aortic aneurism repair. Aortic arch surgery requiring circulatory arrest bears significant risk of brain injury. Methods Descending aorta cannulation and perfusion, preservation of its posterior wall, lumbar paravertebral NIRS and femoral arterial invasive pressure monitoring were used as spinal cord protective strategies. Cerebral antegrade perfusion, initially unilateral and then bilateral, with BIS and cerebral NIRS monitoring were the key components of the cerebral protection strategy. A bilateral erector spinae plane block (BESPB) was performed to allow good pain control in the postoperative period, early extubation and rehabilitation. Intravenous antifibrinolytic, goal directed transfusion therapy and maintaining a coagulation friendly environment were the mainstays of the non-surgical hemostasis strategy. Results The patient was successfully extubated in the operating room presenting no neurological deficits. The surgical drains were removed on the fifth day; on the following day it was necessary to surgically remove part of the left thoracic drain, under combined anesthesia with the ipsilateral ESPB catheter. The remaining postoperative period was uneventful and the patient was discharged home in the 10th postoperative day. Discussion No subarachnoid catheter was placed (to drain cerebrospinal fluid to protect the spinal cord from ischemia), after discussing it in advance with the surgical team, given the risks associated with it and the protective strategy to be adopted: direct perfusion of the descending aorta, preservation of its posterior wall, lumbar paravertebral NIRS ant femoral arterial invasive pressure monitoring., in the intraoperative period, on table extubation and direct neurological monitoring, together with adequate systemic arterial pressures, in the immediate postoperative period. Good pain control with BESPB and on table extubation allowed for early rehabilitation

Intrathecal Access Through Suboccipital Port in Patients With Spinal Muscular Atrophy and Complex Spines: Case Series and Technical Note.

IntroductionMany patients with the spinal muscular atrophy (SMA) have complex spinal anatomy, secondary to thoraco-lumbar spinal fusions. Their fragile musculoskeletal anatomy potentiates limb and joint injury if conventional spinal fluid access modalities are utilized. This creates a challenge when attempting to deliver intrathecal medications such as nusinersen (Spinraza®). Catheter placement in the cervical subarachnoid space with a caudally directed tip is potentially beneficial. This article describes our experience with Spinraza injections into the thecal space through a suboccipital port. This allowed for simple, chronic, and reliable cerebrospinal fluid (CSF) aspiration and intrathecal injections.MethodsA total of 15 patients with SMA and complex spinal anatomy were implanted with a cervical subarachnoid catheter, connected to a suboccipital access port. We retrospectively reviewed the charts of these patients for clinical outcomes and complications. All patients then underwent serial port cannulation, aspiration of CSF, and injection of Spinraza following standard manufacturer dosage guidelines.ResultsThe age range was 3 to 49. Two had type-1 SMA, 10 had type-2 SMA, and three had type-3 SMA. We were able to successfully cannulate the port, aspirate CSF, and inject Spinraza during all access attempts. Two incidents of subcutaneous CSF leaks were resolved through reoperation and one incident of transient CSF leak was resolved without surgical repair.ConclusionPatients with SMA requiring intrathecal injections of Spinraza can be treated safely and efficiently with this novel implantation technique. The complication rates are low and the injection time is dramatically lower than with conventional injection techniques.

Cervical Epidural and Subarachnoid Catheter Placement in Standing Adult Horses.

Horses underwent either cervical epidural space (CES) catheterization or subarachnoid space (SAS) catheterization while restrained in stocks, under deep sedation (detomidine and morphine) and local anesthesia (mepivacaine 2%) block. Catheters were placed under ultrasound guidance with visualization of the dura, SAS, and spinal cord between the first (C1) and second (C2) cervical vertebrae. Following sedation and sterile skin preparation, operator 1 placed under ultrasound guidance, a 6- or 8-inch Tuohy needle with the bevel oriented caudally. For CES, a 6-inch Touhy needle was used with the hanging drop technique to detect negative pressure, and operator 2 then passed the epidural catheter into the CES. For SAS, following puncture of the dura, cerebrospinal fluid (CSF) was aspirated prior to placement of the epidural catheter. Placement into either CES or SAS was confirmed with plain and contrast radiography. Catheters were wrapped for the duration of the study. CSF cytology was assessed up to every 24 h for the study period. Horses were assessed daily for signs of discomfort, neck pain, catheter insertion site swelling, or changes in behavior. A complete postmortem assessment of the spinal tissues was performed at the end of the study period (72 h). Two horses had CES catheters and five horses had SAS catheters placed successfully. All horses tolerated the catheter well for the duration of the study with no signs of discomfort. Ultrasound was essential to assist placement, and radiography confirmed the anatomical location of the catheters. CSF parameters did not change over the study period (P > 0.9). There was evidence of mild meningeal acute inflammation in one horse and hemorrhage in another consistent with mechanical trauma. Placement of an indwelling CES or SAS catheter appears to be safe, technically simple, and well tolerated in standing sedated normal horses.

Feasibility study on continuous spinal analgesia in all stages of labor.

Feasibility study on continuous spinal analgesia in all stages of labor.

Meningitis associated with the use of a subarachnoid catheter with an external infusion system in the treatment of oncologic pain. Case report

Meningitis associated with the use of a subarachnoid catheter with an external infusion system in the treatment of oncologic pain. Case report

Comparison of two modified methods of intrathecal catheterization in rats.

The study designed to compare two different methods of intrathecal catheterization in rats and to develop a simple and safe drug administration in cervical spinal canal of rats. The subarachnoid catheterization was performed via either atlanto-occipital membrane or laminectomy at L3–4 in rats. Body weight, Basso, Beattie, and Bresnahan (BBB) locomotion rating scores and forelimb locomotor rating scale (FLS) were measured on pre-operative day 1 and postoperative day 1, 7, 14, respectively. FLS score of 37.5% rats and BBB score of 50% rats in the atlanto-occipital approach (AOA) group decreased, but no rats showed locomotor impairment in the lumber approach (LA) group. The mean body weight of rats in AOA group reduced significantly compared with LA group. In LA group, 62.5% of catheter tips were located at T1, and in AOA group, the tips of catheter located at C2 in 62.5% cases. The PE10 catheter can be successfully inserted into the spinal intrathecal space for chronic delivery of drugs either via L3–L4 interlaminar space or via atlanto-occipital membrane. And the subarachnoid catheterization via L3–L4 interlaminar space could be easily placed at T1 with little complication.

Cerebrospinal Fluid Fistula for the Craniofacial Surgeon: A Review and Management Paradigm.

Craniofacial surgeons perform operations that involve exposure of the dura. Typical procedures include cranial vault remodeling (CVR), fronto-orbital advancement (FOA), Le Fort III, monobloc, bipartition advancement, or distraction. Cerebrospinal fluid (CSF) fistulas remain one of the most common complications encountered, occurring in up to 30% of patients. Cerebrospinal fluid fistulas can be encountered intraoperatively, acutely, or in the late postoperative period. Traditional management has been well described in the neurosurgical literature. While several studies of complications exist, there is a relative lack of adequate information for craniofacial surgeons. The authors review current literature and provide 3 patients to illustrate our management paradigm.The authors review 30 years of experience at our institution and the pertinent literature. The mean rate of CSF fistula was 11.2%; rates were lowest for FOA/CVR, 5.5%. Patients with fistulas persisting after 2 days of conservative therapy or whom were symptomatic prompted placement of a lumbar subarachnoid catheter. Failure of the leak to resolve with CSF diversion prompted exploration and therapy which could include a patch, pericranial flap, and/or endonasal repair with septal flaps. Three patients are used to illustrate the paradigm, all of which have had no recurrence thus far.Cerebrospinal fluid fistula remains one of most common complications craniofacial surgeons encounter. Although neurosurgeons are often part of the clinical team, the craniofacial surgeon should be familiar with all aspects of treatment. Prompt diagnosis and appropriate knowledgeable management may avoid morbidity and mortality.

TMOD-12. A NOVEL PATIENT-DERIVED XENOGRAFT MODEL OF BRAIN METASTASIS

The establishment of a disease model that adequately reflects the characteristics of metastatic brain tumors is crucial to the development of novel therapeutics. Patient-derived xenograft (PDX) models have a high clinical relevance, offering the potential for individualized patient treatment. Previous research demonstrated that successful PDX modeling can be achieved by direct intracranial implantation of metastatic cells or tissue into the lateral ventricle and frontal cortex, or through the use of a subarachnoid catheter placed into the cisterna magna. However, it is not known if one method is superior. Since injection of metastatic cells into the cerebrospinal fluid (CSF) increases the probability of cancer cell dissemination, we hypothesized that CSF injection of metastatic cells would yield a higher success rate of tumor development compared to animals that were injected in the frontal cortex. Patient-derived brain metastases obtained at surgery were immediately processed into single cell suspension and adaptively cultured as spheres in progenitor cell-enriching condition. After passage 2-6, 5 X 104 – 1 X 105 cells were injected into the frontal cortex, lateral ventricle, or cerebral aqueduct of female athymic nude mice at 6 – 10 weeks of age. The brains of neurologically symptomatic mice were histologically examined using 5-micron paraffin sections. We found that mice injected at the cerebral aqueduct displayed higher rate of tumorigenicity and shorter time to tumor development than those injected at the frontal cortex or lateral ventricle. (Figure 1) To the best of our knowledge this is the first report in which the cerebral aqueduct has been targeted for metastatic PDX modeling. Our data indicate that intracranial injection of metastatic cells into the cerebral aqueduct is a reproducible model to study both local growth of metastases and leptomeningeal disease.

The Importance of Subarachnoid Catheter in Low Dose Spinal Anesthesia Technique

The Importance of Subarachnoid Catheter in Low Dose Spinal Anesthesia Technique

The Importance of Subarachnoid Catheter in Low Dose Spinal Anesthesia Technique

The Importance of Subarachnoid Catheter in Low Dose Spinal Anesthesia Technique

Myoclonus following spinal anaesthesia - case report of a rare complication

Myoclonus is sudden development of involuntary, repetitive, irregular contractions of a group of muscles. Spinal tumours, infections, vascular lesions can result in spinal myoclonus. It can also be triggered by drugs used in spinal anaesthesia, placement of a subarachnoid catheter and use of contrast. Reports of myoclonus following spinal anesthesia in adults are extremely rare. We encountered a case of myoclonus following spinal anaesthesia which was successfully managed.

Comparison of therapeutic effect of different treatments for cerebrospinal fluid leakage induced by surgical operation of spinal fracture combined with dural injury

Objective To compare the therapeutic effect of three treatments for cerebrospinal fluid leakage induced by surgical operation of spinal fracture combined with dural injury. Methods From June 2005 to June 2010, 64 patients with cerebrospinal fluid leakage after surgery to spinal fracture combined with dural injury were analyzed. Patients were treated with positioning adjustment and incision pressure dressing (Group A, n=21), with cerebrospinal fluid leakage drainage via a lumbar percutaneous subarachnoid catheter (Group B, n=21), and with continuous wound drainage followed by catheter removing and wound closure when wound is completely healed (Group C, n=22). Time to stop cerebrospinal fluid leaking from a surgical incision, wound healing time, success rate in the primary intervention and postoperative complications were reviewed among these groups. Results In Group A, the incisional cerebrospinal fluid leakage disappeared at (19.0±3.9)days, with healing time of (25.0±4.6)days. The primary wound healing was achieved in 13 patients but failure to the primary intervention occurred in 8 patients, of whom 6 patients presented complications which were then cured. In Group B, the incisional cerebrospinal fluid leakage disappeared at (3.0±1.0)days, with healing time of (16.0±2.6)days. There were 15 patients with primary wound healing but 6 patients got healing after further treatment, with no complications occurred. In Group C, there was no incisonal cerebrospinal fluid leakage or complications and all patients presented primary wound healing in a period of (13.0±1.0)days. Healing time was shorter and success rate in the primary intervention in Group C was higher than those in Groups A and B (P<0.05). Conclusions Continuous wound drainage till catheter removal and wound closure on complete wound healing is a good choice for treating cerebrospinal fluid leakage induced by surgical operation of spinal fracture combined with dural injury, for it has advantages of good incisional healing, high success rate and few complications in the primary treatment. Key words: Spinal fractures; Complications; Cerebrospinal fluid; Dural injury

Milrinone Via Lumbar Subarachnoid Catheter for Vasospasm After Aneurysmal Subarachnoid Hemorrhage

Delayed ischemic neurological deficit (DIND) due to symptomatic vasospasm is a major cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). The aim of this study was to elucidate the safety and feasibility of intrathecal milrinone infusion via lumber subarachnoid catheter for prevention of DIND after aSAH. We diagnosed 425 consecutive patients with aSAH who received clipping or coil embolization within 48h after arrival. Patients with the evidence of vasospasm on CT angiography (CTA) received the milrinone therapy via lumbar subarachnoid catheter. DIND, delayed cerebral infarction (DCI), and modified Rankin scale at 3months after SAH were used for the assessment of outcome. Of 425 patients, 170 patients (40.0%) with CTA-proven vasospasm received the milrinone therapy. DIND was observed in 68 patients (16.0%), DCI in 30 patients (7.1%), and the overall mortality was 7.2%. In patients with WFNS grade IV and V aSAH, 26 out of 145 patients (17.9%) were presented with DIND, 12 (8.3%) with DCI, and the mortality was 16.0%. No major complication related to the milrinone injection was observed. Intrathecal milrinone injection via lumbar catheter was safe and feasible, and further randomized prospective studies are needed to confirm the effectiveness of this regimen in the patients with SAH.

Continuous 24-Hour Leptin, Proopiomelanocortin, and Amino Acid Measurements in Human Cerebrospinal Fluid: Correlations With Plasma Leptin, Soluble Leptin Receptor, and Amino Acid Levels

In order to characterize diurnal changes in central leptin and its target neuropeptide, proopiomelanocortin (POMC), we measured leptin and POMC in cerebrospinal fluid (CSF) as related to changes in plasma leptin and soluble leptin receptor (sOB-R) levels. CSF and plasma levels of 20 amino acids (AA) were also measured because AA can affect brain POMC. Stored CSF and plasma samples obtained from eight healthy subjects who served as controls for a previous study were evaluated. CSF was collected hourly over 33 h via indwelling subarachnoid catheter. Leptin, sOB-R, and POMC were measured by sensitive ELISA and AA by gas chromatography-mass spectrometry. There was a diurnal rhythm for plasma leptin with a peak at 2200 h (144% of baseline) and there was a similar diurnal rhythm for CSF leptin with a peak (117%) 3-5 h after the plasma peak. Plasma sOB-R was lowest at 0300 h and correlated negatively with plasma and CSF leptin. A diurnal rhythm for POMC in CSF was also detected with a peak (125%) at 0100 h. A positive correlation existed between CSF POMC and leptin in individual subjects over time. CSF levels of many AA increased at night. There was a significant correlation between CSF POMC and 10 AA, including leucine, isoleucine, tryptophan, and tyrosine. Diurnal changes occur in leptin and POMC in human CSF that likely reflect changes in central leptin and melanocortin activity. Our results suggest that nocturnal elevations in leptin, AA, and POMC may help to suppress appetite and feeding at night.

Le positionnement d’un cathéter péridural thoracique stimulant par voie lombaire provoque des lésions importantes à la moelle épinière sur un modèle porcin

Continuous thoracic epidural analgesia is a valuable and common technique for analgesia but involves risk to the spinal cord. There is significant pediatric experience safely placing thoracic epidurals via a caudal approach. The use of a stimulating catheter offers the advantage of real-time confirmation of appropriate catheter placement. We hypothesize that the tip of a stimulating epidural catheter can be reliably advanced to the thoracic epidural space with lumbar insertion in a porcine model. This prospective experimental porcine study evaluated the feasibility of placing the tip of a stimulating epidural catheter to a predefined thoracic epidural location after percutaneous lumbar epidural access in six live pigs. After the lumbar epidural space was accessed, a stimulating epidural catheter was advanced until the targeted thoracic myotome was stimulated. The final position of the catheter in relation to the targeted location was determined by fluoroscopy. All animals were euthanized at the end of the experiment, necropsy and spinal cord histology were then performed to assess the extent of spinal cord damage. In all animals the epidural catheter tip could be accurately advanced to the targeted thoracic myotome. Gross subdural bleeding occurred in three of the six animals and deep spinal damage was observed in two of the six animals. In one animal, the catheter was placed in the subarachnoid space. Accurate access to the thoracic epidural space is possible via a lumbar approach using a stimulating epidural catheter. Based on gross and histopathological examination, this technique resulted in frequent complications, including subdural hemorrhage, deep spinal cord damage, and subarachnoid catheter placement.

Basic fibroblast growth factor attenuates the degeneration of injured spinal cord motor endplates.

The distal end of the spinal cord and neuromuscular junction may develop secondary degeneration and damage following spinal cord injury because of the loss of neural connections. In this study, a rat model of spinal cord injury, established using a modified Allen's method, was injected with basic fibroblast growth factor solution via subarachnoid catheter. After injection, rats with spinal cord injury displayed higher scores on the Basso, Beattie and Bresnahan locomotor scale. Motor function was also well recovered and hematoxylin-eosin staining showed that spinal glial scar hyperplasia was not apparent. Additionally, anterior tibial muscle fibers slowly, but progressively, atrophied. nohistochemical staining showed that the absorbance values of calcitonin gene related peptide and acetylcholinesterase in anterior tibial muscle and spinal cord were similar, and injection of basic broblast growth factor increased this absorbance. Results showed that after spinal cord injury, the distal motor neurons and motor endplate degenerated. Changes in calcitonin gene related peptide and acetylcholinesterase in the spinal cord anterior horn motor neurons and motor endplate then occurred that were consistent with this regeneration. Our findings indicate that basic fibroblast growth factor can protect the endplate through attenuating the decreased expression of calcitonin gene related peptide and acetylcholinesterase in anterior horn motor neurons of the injured spinal cord.

Detection of Surgery-related Spinal Cerebrospinal Fluid Leakage Using Magnetic Resonance Myelography

An incidental dural tear resulting in cerebrospinal fluid (CSF) leakage is a complication of spinal surgery, with a reported incidence of between 0.3% and 16% (1, 2). The patient is likely to experience symptoms of CSF hypovolemia, including postural headache plus nausea, vomiting, pain or tightness in the neck or back, dizziness, diplopia, photophobia, tinnitus, and/or blurred vision. The usual treatment of CSF leakage consists of drainage of the CSF through a subarachnoid catheter (3) and surgical repair of the dural tear (4), although an epidural blood patch may also be used (5). To provide appropriate treatment, it is essential to detect the exact site of CSF leakage. Among the diagnostic modalities used to determine the site of CSF leakage are magnetic resonance (MR) imaging, computed tomographic (CT) cisternography, and radioisotope cisternography. Here, we describe two patients with surgery-related CSF leakage in whom the leakage sites were accurately detected on MR myelography.

Increased NMDA receptor inhibition at an increased Sevoflurane MAC

BackgroundSevoflurane potently enhances glycine receptor currents and more modestly decreases NMDA receptor currents, each of which may contribute to immobility. This modest NMDA receptor antagonism by sevoflurane at a minimum alveolar concentration (MAC) could be reciprocally related to large potentiation of other inhibitory ion channels. If so, then reduced glycine receptor potency should increase NMDA receptor antagonism by sevoflurane at MAC.MethodsIndwelling lumbar subarachnoid catheters were surgically placed in 14 anesthetized rats. Rats were anesthetized with sevoflurane the next day, and a pre-infusion sevoflurane MAC was measured in duplicate using a tail clamp method. Artificial CSF (aCSF) containing either 0 or 4 mg/mL strychnine was then infused intrathecally at 4 μL/min, and the post-infusion baseline sevoflurane MAC was measured. Finally, aCSF containing strychnine (either 0 or 4 mg/mL) plus 0.4 mg/mL dizocilpine (MK-801) was administered intrathecally at 4 μL/min, and the post-dizocilpine sevoflurane MAC was measured.ResultsPre-infusion sevoflurane MAC was 2.26%. Intrathecal aCSF alone did not affect MAC, but intrathecal strychnine significantly increased sevoflurane requirement. Addition of dizocilpine significantly decreased MAC in all rats, but this decrease was two times larger in rats without intrathecal strychnine compared to rats with intrathecal strychnine, a statistically significant (P < 0.005) difference that is consistent with increased NMDA receptor antagonism by sevoflurane in rats receiving strychnine.ConclusionsGlycine receptor antagonism increases NMDA receptor antagonism by sevoflurane at MAC. The magnitude of anesthetic effects on a given ion channel may therefore depend on the magnitude of its effects on other receptors that modulate neuronal excitability.

Abstract 3789: Development of an animal model for microdialysis sampling of pons and cerebral cortex in rhesus macaques

Abstract Background: We developed a nonhuman primate model using rhesus macaques (Macaca mulatta) to compare drug exposure in cortical brain, pontine tissue, and cerebrospinal fluid (CSF) during systemic administration of chemotherapeutic agents by microdialysis (MD), a continuous in vivo extracellular sampling technique. Pediatric diffuse intrinsic pontine gliomas are aggressive brainstem tumors that respond minimally to chemotherapy. We hypothesize that, because of its role in maintaining basic life-sustaining functions, the protective features of the pons, including the blood brain barrier and the blood-cerebrospinal fluid barrier, may further limit antitumor agents from entering the pons compared to cortical brain tissue. Methods: The coordinates and surgical approach for probe placement were determined using 3T MRI (Philips Healthcare, Best Netherlands) and OsiriX imaging software (v 3.9.4) in 4 adult male rhesus macaques (Macaca mulatta). Custom MD cannulas and probes (CMA, Solna, Sweden) were stereotactically implanted in the brain. The pontine MD cannula (34 mm) was implanted superior to the pons, and the MD probe (34 mm shaft plus 8 mm membrane) was then lowered through the cannula, into the pons. The cortical MD cannula (10 mm) was implanted in frontal cortex and a MD probe (10 mm shaft plus 8 mm membrane) was lowered through the cannula. The MD probe inlet/outlet capillaries were connected to a MD infusion pump (CMA 106, flow rate 0.3 µL/min). Retrodialysis was performed to assess in vivo recovery. A systemic intravenous (IV) drug infusion of temozolomide was then administered over 1hr. Single continuous MD samples were collected from both the pons and cortex over 4 hours with concurrent serial plasma and CSF samples (via a subarachnoid or lumbar catheter). Post-surgical MRI verification of MD probe placement was obtained in 2 of 4 animals. Verification of probe placement was obtained via gross pathology and histology in all 4 animals. Results: MRI-determined coordinates and surgical approach for MD probe placement and sample collection in the pons and cerebral cortex was successful in 3 of 4 animals. Surgical monitoring for heart and respiration rates, ETCO2 and SPO2 remained normal in all animals during probe placement and sample collection. Conclusions: MRI-determined coordinates and surgical methodologies resulted in accurate placement of a MD probe in the pons and cerebral cortex of a rhesus macaque allowing for MD sampling from these sites, in conjunction with CSF and plasma sampling, following systemic drug administration. This new animal model allows for the determination of differences in penetration of chemotherapeutic agents in pons, cerebrum, and CSF following systemic drug administration. Additionally, this model provides the foundation for a subcutaneous, semi-permanent, closed system for CNS MD probe placement and continuous sampling in rhesus macaques. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3789. doi:1538-7445.AM2012-3789