Localizing the point: evolving principles of surgical navigation.
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Electrophysiology↗
Biomedical subjects
M L Apuzzo
Publications and source records attributed to M L Apuzzo.
Dosimetric comparison of three photon radiosurgery techniques for an elongated ellipsoid target.
PURPOSE: To examine the dosimetric differences among three radiosurgery techniques: gamma knife, linac multiple arcs, and conformally-shaped static fields. METHODS AND MATERIALS: A simulated target was taken to be a prolate ellipsoid, 25 mm in diameter, 35 mm in length, centrally located in a three-dimensional (3D) model of a patient head taken from MR images. Single isocenter linac treatment plans were developed, 9 portals for the static shaped field technique, and a 7-arc plan for the multiple arc method. A total of 13 isocenters with 3 different collimators were used in the gamma knife plan. RESULTS: At dose levels from 25% to 50% of the reference dose, multiple arc and shaped-field plans treated a greater volume than the gamma knife plan. The linac plans, however, delivered the dose more homogeneously across the target volume as compared to the gamma knife plan. For the dose levels between 50-100%, the shaped fields and gamma knife plan have a similar dose distribution, and treated slightly less volume than the multiple arc plan. CONCLUSION: For a target of limited volume and essentially any shape, one can obtain closely conformal dosimetry with the gamma knife. For a regular-shaped target, the single isocenter multiple arc technique gives a more homogenous dose distribution within the target. Static shaped fields offer an alternative radiosurgery technique, with dosimetry similar to the multiple arc method, applicable to targets of any shape.
Head↗
Gamma knife radiosurgery for metastatic melanoma: an analysis of survival, outcome, and complications.
OBJECTIVE: Although the mainstays for treatment of metastatic brain disease have been surgery and/or external beam radiation therapy, an increasing number of patients are being referred for stereotactic radiosurgery as the primary intervention for their intracranial pathological abnormalities. The lack of efficacy and cognitive and behavioral consequences of whole brain irradiation have prompted clinicians to select patients for alternative therapies. This study analyzes the effectiveness of Leksell gamma unit therapy for metastatic melanoma to the brain. METHODS: We present our experience with 59 Leksell gamma unit treatment sessions in 45 consecutive patients who presented with metastatic melanoma to the brain. Five of these procedures were performed as salvage therapy for patients who needed second radiosurgical treatment for new lesions that were remote from the previous targets and were not included in the overall analyses. RESULTS: The population included 78% male patients. The mean patient age was 53 years (age range, 24-80 yr). The mean time from diagnosis of primary melanoma to discovery of brain metastasis was 43 months (median, 27.5 mo; range, 1-180 mo). At the time of diagnosis of brain disease, 35.5% of the patients (16 of 45 patients) had neurological symptoms, 77.7% (35 of 45 patients) had known visceral metastases, and 11.1% (5 of 45 patients) had seizure disorders. Eighty-six percent of the lesions (80 of 93 lesions) were cortical, 12% (11 of 93 lesions) were cerebellar, 1% (1 of 93 lesions) were pontine, and 1% (1 of 93 lesions) were thalamic. Fifty-seven percent of the sessions (31 of 54 sessions) were performed for a single lesion, 24.1% (13 of 54 sessions) for two lesions, 9.2% (5 of 54 sessions) for three lesions, 7.4% (4 of 54 sessions) for four lesions, and 1.8% (1 of 54 sessions) for five lesions. The mean treatment volume was 5.6 cc, with a mean prescription of 21.6 Gy to the 56.0% mean isodose line. The median survival time of the patients in our population, using Kaplan-Meier curves, was 43 months from the time of diagnosis of primary melanoma (range, 3-180 mo) and 8 months (range, 1-20 mo) from the time of gamma knife treatment. Complications included seizures within 24 hours of the procedure in four patients, with transient nausea and vomiting in three patients, transient worsening of preprocedure paresis responsive to steroids in three patients, and increased confusion in one patient. All 45 patients were located for follow-up (mean follow-up duration, 1 yr). After gamma knife treatment, 78% of the patients (35 of 45 patients) experienced either improved or stable neurological symptomatology before death or at the time of the latest follow-up examination. There were 26 deaths (58%). The cause of death was determined to be neurological in only 2 of 45 patients (7.7%). Follow-up magnetic resonance images revealed a 97% local tumor control rate of gamma knife-treated lesions, with 28% radiographic disappearance (9 of 32 cases). Six patients developed new lesions remote from radiosurgical targets and underwent second procedures. CONCLUSION: Although metastatic melanoma to the brain continues to have a foreboding prognosis for long-term survival, gamma knife radiosurgery seems to be a relatively safe, noninvasive, palliative therapy, halting or reversing neurological progression in 77.8% of treated patients (35 of 45 patients). The survival rate matches or exceeds those previously reported for surgery and other forms of radiotherapy. Only 7.7% of the patients in our study population who died as a result of metastatic melanoma (2 of 26 patients) died as a result of neurological disease. The routine use of therapeutic level antiseizure medication is emphasized, considering the findings of our review.
Adult↗
Intracerebral Whipple's disease diagnosed by stereotactic biopsy: a case report and review of the literature.
OBJECTIVE AND IMPORTANCE: This case demonstrates the rare occurrence of intracerebral Whipple's disease in a patient lacking classic systemic manifestations of the disease. Because of the nonspecific presentation and the typically deep-seated location of cerebral lesions in these patients, definitive diagnosis is frequently problematic. We present the first reported use of stereotaxy-guided brain biopsy to confirm the diagnosis of isolated intracranial Whipple's disease. CLINICAL PRESENTATION: The patient was a 36-year-old man who presented with a 4-month history of progressive lethargy, hypersomnia, behavioral changes, and weight gain. The results of the physical examination were remarkable only for findings of hypogonadism. Subsequent laboratory evaluation confirmed the diagnosis of hypogonadotrophic hypogonadism, with low levels of testosterone, luteinizing hormone, cortisol, and prolactin. INTERVENTION: A magnetic resonance image of the brain demonstrated hyperintense lesions on T2-weighted images in the regions of the right fornix, hypothalamus, and putamen that subsequently enhanced with intravenously administered contrast medium. A biopsy was then obtained from the right putaminal lesion under stereotactic guidance. Histopathological analysis of the tissue revealed findings consistent with intracerebral Whipple's disease that were subsequently confirmed using electron microscopy. CONCLUSION: Intracerebral Whipple's disease should be included in the differential diagnosis of patients presenting with progressive dementia and cognitive decline. In these patients, lesions have typically been observed in the hypothalamus, cingulate gyrus, basal ganglia, insular cortex, and cerebellum. As evidenced by our case, stereotaxy affords clinicians the attractive option of a minimally invasive technique by which to obtain tissue from such deep-seated areas. A review of this rare neurosurgical entity is presented.
Adult↗
The Bayeux Tapestry: a charter of a people and a unique testimony of creative imagery in communication.
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Art↗
The development of anatomic art and sciences: the ceroplastica anatomic models of La Specola.
Anatomic models are important heuristic aids for surgeons in training. They are uniquely able to convey the three-dimensional relationships of anatomic structures with a physical immediacy not allowed by any other media. We examine the conceptual development of the anatomic model in light of the history of neuroanatomic understanding and coexistent artistic movements. The teaching anatomic model traces its ancestry to the work of Gaetano Zumbo in the late 17th century, on the heels of important anatomic discoveries made in the preceding 100 years of investigation. The anatomic model reached its peak expression in the late 18th century with the founding of the ceroplastica laboratory in Florence. We discuss the technological, artistic, and scientific origins of the anatomic wax model and the conditions that allowed it to flourish in the late 18th century.
Anatomy, Artistic↗
Retroviral vector-mediated transfer and expression of human tissue plasminogen activator cDNA in bovine brain endothelial cells.
OBJECTIVES: Gene transfer of thrombolytic enzymes to vascular endothelial cells may influence the kinetics of intravascular thrombosis. This study defines the potential for gene transfer of tissue plasminogen activator (tPA) into bovine brain endothelial cells (BBEC). METHODS: The retroviral vectors derived from murine leukemia virus (MuLV) were used to transfer human tPA cDNA to BBEC. The tPA activity, tPA antigen and tPA inhibitor 1 (PAI-1) antigen were determined in the supernatant of transduced (BBEC/tPA) cell cultures by an immunoassay. RESULTS: The tPA antigen and enzymatic activity in cell culture supernatants of BBEC/tPA transduced cells were 75 ng/ml and 14 IU/ml after 4 days, that was 25 and 28-fold higher compared to the respective values in control cells. The PAI-1 antigen was not affected by tPA cDNA transfer. The Western blot assay of cell lysates confirmed that the majority of tPA in BBEC/tPA transduced cells was in the form of free tPA. While the maximal transduction efficiency of BBEC with an amphotropic MuLV vector was about 15%, a MuLV pseudotyped with vesicular stomatitis virus G glycoprotein envelope achieved high > 90% maximal transduction efficiency. CONCLUSIONS: The fibrinolytic activity of brain endothelial cells can be enhanced by transferring human tPA cDNA. These findings provide an initial step in implementation of future studies that investigate the use of this technology as an adjunctive treatment for cerebrovascular disease.
Animals↗
Summa cum laude.
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History, 19th Century↗
Stereotaxy, navigation and the temporal concatenation.
Nautical and cerebral navigation share similar elements of functional need and similar developmental pathways. The need for orientation necessitates the development of appropriate concepts, and such concepts are dependent on technology for practical realization. Occasionally, a concept precedes technology in time and requires periods of delay for appropriate development. A temporal concatenation exists where time allows the additive as need, concept and technology ultimately provide an endpoint of elegant solution. Nautical navigation has proceeded through periods of dead reckoning and celestial navigation to satellite orientation with associated refinements of instrumentation and charts for guidance. Cerebral navigation has progressed from craniometric orientation and burr hole mounted guidance systems to simple rectolinear and arc-centered devices based on radiographs to guidance by complex anatomical and functional maps provided as an amalgam of modern imaging modes. These maps are now augmented by complex frame and frameless systems which allow not only precise orientation, but also point and volumetric action. These complex technical modalities required and developed in part from elements of maritime navigation that have been translated to cerebral navigation in a temporal concatenation.
Animals↗
Stereotactic radiosurgery in the treatment of metastatic disease to the brain.
We review 190 consecutive patients with 434 metastatic tumors treated by gamma knife stereotactic radiosurgery, from August 1994 to February 1999. Median actuarial survival for all patients was 34 weeks. Factors correlated with significantly improved survival included controlled systemic disease and nonmelanoma histology. We found that no significant survival benefit could be discerned from adjuvant whole brain radiotherapy in this patient group. Survival was not statistically different for patients initially presenting with 1-4 metastases at initial treatment.
Brain Neoplasms↗
Long-term multicenter experience with vagus nerve stimulation for intractable partial seizures: results of the XE5 trial.
OBJECTIVE: Intermittent stimulation of the left cervical vagus nerve trunk (VNS) with the NeuroCybernetic Prosthesis (NCP) is emerging as a novel adjunct in the management of medically refractory epilepsy. We review the safety and efficacy of VNS 1 year after completion of the E05 study, the largest controlled clinical trial of VNS to date. METHODS: One hundred and ninety-nine patients with intractable epilepsy and at least 6 complex partial or secondarily generalized seizures per month enrolled in a randomized, double-blinded, partial crossover trial of high versus low parameters of stimulation (E05). After 3 months, all patients received high stimulation during an open-label, nonblinded extension trial (XE5). Seizure frequency, adverse events and multiple physiologic variables were monitored at regular intervals. RESULTS: At 3 months, the mean reduction in seizure frequency among patients receiving high stimulation during E05 was 28%. Of the 199 subjects participating in this acute-phase trial, 195 continued in the long-term protocol. Among the latter patients, 21 subsequently exited the study due to lack of efficacy, and 2 others died from causes unrelated to VNS. Complete data were obtained for 164 of the remaining subjects. Using a declining N analysis, the mean and median reduction in seizure frequency at 15 months was 37 and 45%, respectively. A last visit carried forward analysis, which controls for dropouts and incomplete follow-up, yielded comparable results (34 and 45%, respectively), indicating little potential for selection bias. At 15 months, 39% of the subjects had a greater than 50% reduction in seizures, including 21% who had a greater than 75% reduction, and 2% have remained seizure free. Few serious adverse events, physiological perturbation or device failures were reported. CONCLUSIONS: The long-term multicenter safety, efficacy, feasibility and tolerability of VNS, as well as the durability of the NCP device have been confirmed. Unlike chronic therapy with antiepileptic medication, the efficacy of VNS is maintained during prolonged stimulation, and overall seizure control continues to improve with time.
Adult↗
TLD measurements of the relative output factors for the Leksell Gamma Knife.
The accuracy of the output factor directly affects the accuracy of dose delivery during patient treatment. At our Gamma Knife center, annual output factor measurements have been carried out by using a high accuracy TLD technique, characterized by the group annealing and sorting (GAS) procedure. For each collimator exposure, one to five LiF Thermoluminescent Dosimeter (TLD) 1 x 1 x 1 mm3 cubes were used, depending upon the collimator size, and the process was repeated until approximately 10 TLDs had been exposed for each collimator. Transit radiation dose accumulated during the motion of the treatment couch was measured for each collimator helmet, and the result was subtracted from the uncorrected TLD dose measurements. The mean values of the output factors for the 14, 8 and 4 mm collimators from last 5 years were 0.985 ¿ 0.001, 0.948 ¿ 0.005 and 0.833 ¿ 0.007, respectively, relative to the 18 mm collimator. These measured relative output factors are virtually identical to the values recommended by the manufacturer for the 14 mm and 8 mm collimators. On the other hand, the output factor for the 4 mm collimator was approximately 4.1% larger than that recommended by the manufacturer. The significance of these findings is discussed.
Radiosurgery↗
Experience with vagus nerve stimulation for intractable epilepsy: some questions and answers.
Vagus nerve stimulation (VNS) is gaining increasing popularity and credibility as a treatment option for patients with intractable epilepsy. VNS is a relatively recent innovation, however, and like many other incipient developments, it has engendered a number of unresolved controversies and perplexities. Limitations in our current understanding of how VNS works lie at the crux of these uncertainties. In this article, we present our clinical experience with VNS and review the fundamental issue which remain unsettled, such as the mechanism of VNS action, the factors underlying variability in patient outcome, and the selection of ideal candidates for VNS therapy. Although many enigmas persist, VNS has proven to be a safe, feasible, and potentially effective method of reducing seizures in select patient populations. It offers several advantages over extant treatments and, as a result, holds much promise for future therapy of medically refractory epilepsy.
Adult↗
Strategies to circumvent vascular barriers of the central nervous system.
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Antineoplastic Agents↗
An institutional experience with cervical vagus nerve trunk stimulation for medically refractory epilepsy: rationale, technique, and outcome.
OBJECTIVE: Intermittent stimulation of the left cervical vagus nerve trunk is emerging as a novel adjunct in the treatment of medically refractory seizures. We sought to evaluate theoretical and practical issues attendant to this concept. We review the anatomic and physiological background arguing for clinical application of vagus nerve stimulation, discuss salient aspects of patient selection and the nuances of surgical technique, and present our observations of and results from application of the method. METHODS: Each of 18 patients with medically refractory epilepsy and at least six complex partial or secondarily generalized seizures per month underwent placement of a NeuroCybernetic Prosthesis pulse generator (Cyberonics, Webster, TX) in the chest, connected to helical platinum leads applied to the left cervical vagus nerve trunk. The patients were then randomized in a double-blinded fashion to receive either high (presumably therapeutic) or low (presumably less therapeutic) levels of vagus nerve stimulation. Reduction in seizure frequency, global assessments of quality of life, physiological measurements, and adverse events were recorded during a 3-month period. Patients in the low group were then crossed over to high-stimulation paradigms during a 15-month extension trial. RESULTS: All operations were successful, uneventful, and without adverse postoperative sequelae. One patient was excluded from analysis because of inadequate seizure calendars. Of the seven patients initially assigned to high stimulation, the mean reduction in seizure frequency was 71% at 3 months and 81% at 18 months. Five (72%) of these patients had a greater than 75% reduction in seizure frequency, and one (14%) remained seizure-free after more than 1.5 years of follow-up. The mean reduction in seizure frequency among the low-stimulation group was only 6% at 3 months. No serious complications, device failures, or physiological perturbations occurred. CONCLUSION: In our experience, vagus nerve stimulation has proven to be a safe, feasible, and potentially effective method of reducing seizures in select patient populations. However, the elements of strict definition for the application of the method require further study.
Adult↗
The development of deaf and hard of hearing children identified early through the high-risk registry.
The high-risk registry was used as a screening device for identifying hearing loss for many decades in Colorado. It reportedly missed approximately 50% of all infants with congenital sensorineural hearing loss (Mehl & Thomson, 1998; Parving, 1993; Watkins, Baldwin, & McEnery, 1991). Little is known about the developmental characteristics of this population. This article describes children identified through the high-risk registry. These children have been divided into two groups according to their age of identification: (a) deaf and hard of hearing children identified before age 6 months, and (b) deaf and hard of hearing children identified between ages 7 and 18 months. The children identified before age 6 months and receiving intervention at an average of 2 to 3 months after identification of hearing loss had significantly higher levels of receptive and expressive language, personal-social development, expressive and receptive vocabulary, general development, situation comprehension, and vowel production. The high-risk registry used for newborn hearing screening has been replaced by universal newborn physiological hearing screening in the state of Colorado.
Age Factors↗
Identification of hearing loss after age 18 months is not early enough.
The general development of 40 deaf and hard of hearing infants was analyzed. The infants were placed into one of two groups according to age at which hearing loss was identified: (a) before age 6 months and (b) after age 18 months. The mean age at testing was 40 months. Developmental quotients (DQs) were used to compare results regardless of the infants' age at time of testing. Infants were evaluated on the basis of their DQ scores on the Minnesota Child Development Inventory (MCDI; Ireton & Thwing, 1972). MCDI subtests include general development, gross motor, fine-motor, expressive language, comprehension-conceptual, situation-comprehension, self-help, and personal-social. Infants whose hearing loss was identified before age 6 months scored significantly higher than those whose hearing loss was identified after age 18 months in the expressive language and comprehension-conceptual subtests. The performance of the earlier-identified group supports the earliest identification of hearing loss and encourages implementation of universal hearing screening.
Adolescent↗
In the realm of ideas: the advent of advanced surgery of the human cerebrum and neurosurgical education.
High technology has recently exerted remarkable positive forces within the field of neurological surgery. Striking developments in brain imaging, stereotaxy, molecular biology, radiation physics and complex data management promise to revolutionize surgery of the human cerebrum. These changes are not without profound impact on national health care economics and present enormous philosophical and educational challenges which will create considerable turmoil over the next decades.
Brain↗