A Prospective Phase I/II Clinical Trial of High-Dose Proton Therapy for Chordomas and Chondrosarcomas

Purpose

The purpose of this study was to evaluate the feasibility and safety of dose-escalated proton beam therapy for treating chordomas and chondrosarcomas of the skull base and spine. Methods: A prospective cohort of 54 patients (42 with chordomas and 12 with chondrosarcomas) was enrolled between 2010 and 2018. The primary endpoints were feasibility and <20% rate of acute grade ≥3 toxicity, and secondary endpoints included cancer-specific outcomes and toxicities. Patients were followed with magnetic resonance imaging or computed tomography at 3-month intervals. Proton beam therapy was delivered with doses up to 79.2 Gy using protons only, combination protons/intensity modulated radiation therapy (IMRT), or IMRT only.

Results

Feasibility endpoints were met, with only 2 out of 54 patient radiation therapy plans failing to meet dosimetric constraints with protons, and 4 out of 54 experiencing a delay or treatment break >5 days, none for toxicities related to treatment. There were no grade 4 acute toxicities and 1 grade 3 acute toxicity (sensory neuropathy). The only 2 grade 3 late toxicities recorded, osteoradionecrosis and intranasal carotid blowout (mild and not emergently treated), occurred in a single patient. We report overall survival as 83% at 5 years, with local failure-free survival and progression-free survival rates of 72% and 68%, respectively. Five patients developed distant disease, and among the 9/54 patients who died, 4 deaths were not attributed to treatment or recurrence.

Conclusions

Our findings suggest that high-dose proton therapy alone or in combination with IMRT is a safe and effective treatment option for chordomas and chondrosarcomas of the skull base and spine.

Transient Elevation of Plasma Glucocorticoids Supports Psilocybin-Induced Anxiolysis in Mice

While correlations between drug-induced cortisol elevation, self-reported anxiety, and treatment outcomes have been reported for human studies during psilocybin-assisted psychotherapy, the mechanistic relationship between psychedelic-associated alterations in plasma glucocorticoid responses and the time course of anxious responsiveness remains unclear. Using rodents, both time-bound manipulation of glucocorticoid concentrations and assessment of anxiety-like behaviors can be achieved. Here, 3 mg/kg IP psilocybin was found to have anxiolytic-like effects in C57BL/6 male mice at 4 h after treatment. These effects were not altered by pretreatment with a 5-HT2A antagonist but were blunted by pretreatment with a glucocorticoid receptor antagonist or suppression of psilocybin-induced corticosterone elevations. Anxiolytic-like effects were also observed at 4 h following treatment with the nonpsychedelic 5-HT2A agonist lisuride at a dose causing a similar increase in plasma glucocorticoids as that seen with psilocybin, as well as following stress-induced (via repeated injection) glucocorticoid release alone. Psilocybin's anxiolytic-like effects persisted at 7 days following administration. The long-term anxiolytic effects of psilocybin were lost when psilocybin was administered to animals with ongoing chronic elevations in plasma corticosterone concentrations. Overall, these experiments indicate that acute, resolvable psilocybin-induced glucocorticoid release drives the postacute anxiolytic-like effects of psilocybin in mice and that its long-term anxiolytic-like effects can be abolished in the presence of chronically elevated plasma glucocorticoid elevations.

Electrophysiological signatures of acute systemic lipopolysaccharide-induced inflammation: potential implications for delirium science

BACKGROUND

Novel preventive therapies are needed for postoperative delirium, which especially affects older patients. A mouse model is presented that captures inflammation-associated cortical slow wave activity (SWA) observed in patients, allowing exploration of the mechanistic role of prostaglandin-adenosine signalling.

METHODS

EEG and cortical cytokine measurements (interleukin 6, monocyte chemoattractant protein-1) were obtained from adult and aged mice. Behaviour, SWA, and functional connectivity were assayed before and after systemic administration of lipopolysaccharide (LPS)+piroxicam (cyclooxygenase inhibitor) or LPS+caffeine (adenosine receptor antagonist). To avoid the confounder of inflammation-driven changes in movement which alter SWA and connectivity, electrophysiological recordings were classified as occurring during quiescence or movement, and propensity score matching was used to match distributions of movement magnitude between baseline and post-LPS administration.

RESULTS

LPS produces increases in cortical cytokines and behavioural quiescence. In movement-matched data, LPS produces increases in SWA (likelihood-ratio test: χ2(4)=21.51, P<0.001), but not connectivity (χ2(4)=6.39, P=0.17). Increases in SWA associate with interleukin 6 (P<0.001) and monocyte chemoattractant protein-1 (P=0.001) and are suppressed by piroxicam (P<0.001) and caffeine (P=0.046). Aged animals compared with adult animals show similar LPS-induced SWA during movement, but exaggerated cytokine response and increased SWA during quiescence.

CONCLUSIONS

Cytokine-SWA correlations during wakefulness are consistent with observations in patients with delirium. Absence of connectivity effects after accounting for movement changes suggests decreased connectivity in patients is a biomarker of hypoactivity. Exaggerated effects in quiescent aged animals are consistent with increased hypoactive delirium in older patients. Prostaglandin-adenosine signalling may link inflammation to neural changes and hence delirium.

Optogenetic Activation of Afferent Pathways in Brain Slices and Modulation of Responses by Volatile Anesthetics

Anesthetics influence consciousness in part via their actions on thalamocortical circuits. However, the extent to which volatile anesthetics affect distinct cellular and network components of these circuits remains unclear. Ex vivo brain slices provide a means by which investigators may probe discrete components of complex networks and disentangle potential mechanisms underlying the effects of volatile anesthetics on evoked responses. To isolate potential cell type- and pathway-specific drug effects in brain slices, investigators must be able to independently activate afferent fiber pathways, identify non-overlapping populations of cells, and apply volatile anesthetics to the tissue in aqueous solution. In this protocol, methods to measure optogenetically-evoked responses to two independent afferent pathways to neocortex in ex vivo brain slices are described. Extracellular responses are recorded to assay network activity and targeted whole-cell patch clamp recordings are conducted in somatostatin- and parvalbumin-positive interneurons. Delivery of physiologically relevant concentrations of isoflurane via artificial cerebral spinal fluid to modulate cellular and network responses is described.

Pigmented Villonodular Synovitis Presenting as Unilateral Hearing Loss: Review of the Literature and Case Report

BACKGROUND/AIMS

To review the existing literature on pigmented villonodular synovitis (PVNS) of the temporomandibular joint (TMJ) and report a rare case of PVNS of the TMJ presenting with unilateral hearing loss.

METHODS

Review of the existing literature and a description of personal experience with PVNS of the TMJ presenting with unilateral hearing loss.

RESULTS

Review of the existing literature revealed 76 reported cases of PVNS of the TMJ. The most common presenting symptom was of a slowly enlarging mass or swelling of the preauricular area, with dysfunctional TMJ also frequently reported. All patients underwent surgical excision with some pursuing radiation as adjuvant therapy. Presented Patient: A 46-year-old man presented with several months of unilateral subjective hearing loss and aural fullness. Imaging revealed a mass centered along the superior TMJ with expansion through the squamous temporal bone and extra-axial intracranial extension into the middle cranial fossa. Imaging characteristics and fine-needle aspiration biopsy were consistent with PVNS.

INTERVENTION

The patient underwent near-total excision of the mass via frontotemporal craniectomy and lateral temporal bone resection.

FOLLOW-UP

At the 16-month follow-up there was no evidence of disease recurrence.

CONCLUSION

PVNS of the TMJ represents a rare entity that can present with a variety of symptoms including unilateral hearing loss.

A prospective clinical trial of proton therapy for chordoma and chondrosarcoma: Feasibility assessment

BACKGROUND/OBJECTIVES

Proton therapy (PRT) has emerged as a treatment option for chordomas/chondrosarcomas to escalate radiation dose more safely. We report results of a phase I/II trial of PRT in patients with chordoma/chondrosarcoma.

METHODS

Twenty adult patients with pathologically confirmed, nonmetastatic chordoma or chondrosarcoma were enrolled in a single-institution prospective trial of PRT from 2010 to 2014. Seventeen patients received adjuvant PRT and three received definitive PRT. Median dose was 73.8 Gy(RBE; range 68.4-79.2 Gy) using PRT-only (n = 6) or combination PRT/intensity-modulated radiotherapy (IMRT) (n = 14). Quality-of-life (QOL) and fatigue were assessed weekly and every 3 months posttreatment with the Functional Assessment of Cancer Therapy - Brain (FACTBr) and Brief Fatigue Inventory. Primary endpoint was feasibility (90% completing treatment with < 10 day treatment delay and ≤ 20% unexpected acute grade ≥ 3 toxicity).

RESULTS

Tumors included chordomas of the skull base (n = 10), sacrum (n = 5), and cervical spine (n = 3), and skull base chondrosarcomas (n = 2). Median age was 57. The 80% had positive margins/gross disease. Median follow-up was 37 months. Feasibility endpoints were met. The 3-year local control and progression-free survival was 86% and 81%. There were no deaths. Two patients had acute grade 3 toxicity (both fatigue). One had late grade 3 toxicity (epistaxis and osteoradionecrosis). There were no significant differences in patient reported fatigue or QOL from baseline to the end-of-treatment.

CONCLUSIONS

We report favorable local control, survival, and toxicity following PRT.

Altered stimulus representation in rat auditory cortex is not causal for loss of consciousness under general anaesthesia

BACKGROUND

Current concepts suggest that impaired representation of information in cortical networks contributes to loss of consciousness under anaesthesia. We tested this idea in rat auditory cortex using information theory analysis of multiunit responses recorded under three anaesthetic agents with different molecular targets: isoflurane, propofol, and dexmedetomidine. We reasoned that if changes in the representation of sensory stimuli are causal for loss of consciousness, they should occur regardless of the specific anaesthetic agent.

METHODS

Spiking responses were recorded with chronically implanted microwire arrays in response to acoustic stimuli incorporating varied temporal and spectral dynamics. Experiments consisted of four drug conditions: awake (pre-drug), sedation (i.e. intact righting reflex), loss of consciousness (a dose just sufficient to cause loss of righting reflex), and recovery. Measures of firing rate, spike timing, and mutual information were analysed as a function of drug condition.

RESULTS

All three drugs decreased spontaneous and evoked spiking activity and modulated spike timing. However, changes in mutual information were inconsistent with altered stimulus representation being causal for loss of consciousness. First, direction of change in mutual information was agent-specific, increasing under dexmedetomidine and decreasing under isoflurane and propofol. Second, mutual information did not decrease at the transition between sedation and LOC for any agent. Changes in mutual information under anaesthesia correlated strongly with changes in precision and reliability of spike timing, consistent with the importance of temporal stimulus features in driving auditory cortical activity.

CONCLUSIONS

The primary sensory cortex is not the locus for changes in representation of information causal for loss of consciousness under anaesthesia.

Preferential effect of isoflurane on top-down vs. bottom-up pathways in sensory cortex

The mechanism of loss of consciousness (LOC) under anesthesia is unknown. Because consciousness depends on activity in the cortico-thalamic network, anesthetic actions on this network are likely critical for LOC. Competing theories stress the importance of anesthetic actions on bottom-up “core” thalamo-cortical (TC) vs. top-down cortico-cortical (CC) and matrix TC connections. We tested these models using laminar recordings in rat auditory cortex in vivo and murine brain slices. We selectively activated bottom-up vs. top-down afferent pathways using sensory stimuli in vivo and electrical stimulation in brain slices, and compared effects of isoflurane on responses evoked via the two pathways. Auditory stimuli in vivo and core TC afferent stimulation in brain slices evoked short latency current sinks in middle layers, consistent with activation of core TC afferents. By contrast, visual stimuli in vivo and stimulation of CC and matrix TC afferents in brain slices evoked responses mainly in superficial and deep layers, consistent with projection patterns of top-down afferents that carry visual information to auditory cortex. Responses to auditory stimuli in vivo and core TC afferents in brain slices were significantly less affected by isoflurane compared to responses triggered by visual stimuli in vivo and CC/matrix TC afferents in slices. At a just-hypnotic dose in vivo, auditory responses were enhanced by isoflurane, whereas visual responses were dramatically reduced. At a comparable concentration in slices, isoflurane suppressed both core TC and CC/matrix TC responses, but the effect on the latter responses was far greater than on core TC responses, indicating that at least part of the differential effects observed in vivo were due to local actions of isoflurane in auditory cortex. These data support a model in which disruption of top-down connectivity contributes to anesthesia-induced LOC, and have implications for understanding the neural basis of consciousness.

Implementation of a departmental picture archiving and communication system: a productivity and cost analysis

BACKGROUND

Digital radiology enhances productivity and results in long-term cost savings. However, the viewing, storage, and sharing of outside imaging studies on compact discs at ambulatory offices and hospitals pose a number of unique challenges to a surgeon's efficiency and clinical workflow.

OBJECTIVE

To improve the efficiency and clinical workflow of an academic neurosurgical practice when evaluating patients with outside radiological studies.

METHODS

Open-source software and commercial hardware were used to design and implement a departmental picture archiving and communications system (PACS).

RESULTS

The implementation of a departmental PACS system significantly improved productivity and enhanced collaboration in a variety of clinical settings. Using published data on the rate of information technology problems associated with outside studies on compact discs, this system produced a cost savings ranging from $6250 to $33600 and from $43200 to $72000 for 2 cohorts, urgent transfer and spine clinic patients, respectively, therefore justifying the costs of the system in less than a year.

CONCLUSION

The implementation of a departmental PACS system using open-source software is straightforward and cost-effective and results in significant gains in surgeon productivity when evaluating patients with outside imaging studies.

GABA and glutamate are not colocalized in mossy fiber terminals of developing rodent hippocampus

It has been hypothesized that, in the developing rodent hippocampus, mossy fiber terminals release GABA together with glutamate. Here, we used transgenic glutamic acid decarboxylase-67 (GAD67)-GFP expressing mice and multi-label immunohistochemistry to address whether glutamatergic and GABAergic markers are colocalized. We demonstrate that in the dentate gyrus, interneurons positive for GABA/GAD are sparsely distributed along the edge of the hilus, in a different pattern from that of the densely packed granule cells. Co-staining for synaptophysin and vesicular glutamate transporter1 (VGLUT1) in postnatal day 14 brain sections from both mice and rats showed mossy fiber terminals as a group of large (2-5 μm in diameter) VGLUT1-positive excitatory presynaptic terminals in the stratum lucidum of area CA3a/b. Furthermore, co-staining for synaptophysin and vesicular GABA transporter (VGAT) revealed a group of small-sized (∼0.5 μm in diameter) inhibitory presynaptic terminals in the same area where identified mossy fiber terminals were present. The two types of terminals appeared to be mutually exclusive, and showed no colocalization. Thus, our results do not support the hypothesis that GABA is released as a neurotransmitter from mossy fiber terminals during development.

Clinical trials in head injury

Traumatic brain injury (TBI) remains a major public health problem globally. In the United States the incidence of closed head injuries admitted to hospitals is conservatively estimated to be 200 per 100,000 population, and the incidence of penetrating head injury is estimated to be 12 per 100,000, the highest of any developed country in the world. This yields an approximate number of 500,000 new cases each year, a sizeable proportion of which demonstrate significant long-term disabilities. Unfortunately, there is a paucity of proven therapies for this disease. For a variety of reasons, clinical trials for this condition have been difficult to design and perform. Despite promising pre-clinical data, most of the trials that have been performed in recent years have failed to demonstrate any significant improvement in outcomes. The reasons for these failures have not always been apparent and any insights gained were not always shared. It was therefore feared that we were running the risk of repeating our mistakes. Recognizing the importance of TBI, the National Institute of Neurological Disorders and Stroke (NINDS) sponsored a workshop that brought together experts from clinical, research, and pharmaceutical backgrounds. This workshop proved to be very informative and yielded many insights into previous and future TBI trials. This paper is an attempt to summarize the key points made at the workshop. It is hoped that these lessons will enhance the planning and design of future efforts in this important field of research.

Alterations in noradrenergic physiological characteristics with DOCA-hypertension: interaction between norepinephrine and GABA in rat lateral hypothalamus

The lateral hypothalamus (LH) is involved in the central integration of fluid and electrolyte balance. Several studies have suggested a role for norepinephrine (NE) in these functions. In previous studies we presented evidence in support of a modulatory role for NE within the LH circuitry. Specifically, NE facilitated responses of LH cells to synaptic inputs and putative transmitters. In the present studies, we examined the influence of NE on the response of LH neurons to the inhibitory amino acid transmitter GABA. Neuronal responses were studied in normal, DOCA hypertensive, and 1% NaCl diet (HSD)-treated rats. Male rats were uninephrectomized and received a DOCA implant (200 mg/kg). They were given 1% NaCl and 0.1% KCl in their drinking water (4-6 weeks). HSD rats received the same treatment, except that no DOCA was given. Extracellularly recorded responses from single LH neurons to iontophoretic pulses (5-50 nA; 10 s duration) of GABA were examined before, during and after NE microiontophoresis (5-50 nA) in anesthetized rats. The results indicated a shift of NE modulatory action from potentiating to antagonizing GABA-induced inhibition. In control rats, NE routinely potentiated GABA depressant responses (19 of 26, 73%), whereas in HSD rats the ability of NE to enhance GABA responses was reduced to 33% of the cases tested (10 of 30). Likewise, NE did not augment, but rather antagonized GABA inhibition in the majority of cells recorded (21 of 35, 60%) from DOCA hypertensive rats. The beta agonist isoproterenol was still capable of potentiating GABA inhibition of LH cells in HSD and DOCA treated animals, suggesting that the change in the capacity of NE to enhance GABA action is not a result of alterations in beta receptor function, but could arise from a modification of the ratio between alpha- and beta-adrenoceptors. NE modulating capability was also altered-in LH neurons responsive to experimentally induced changes in blood pressure. In summary, these findings suggest that chronic HSD and DOCA treatments can alter the modulatory capacities of NE within the LH. These alterations in noradrenergic action within hypothalamic cardiovascular centers might affect the way neurons respond to afferent baroreceptor information, as well as the way they control sympathetic and parasympathetic effector mechanisms. A decrease in the inhibitory capacities of GABA transmission in these areas, due to alterations of NE, may play a role in the genesis of hypertension.

Electrophysiological actions of VIP in rat somatosensory cortex

Electrophysiological and biochemical studies suggest that VIP may exert a facilitating action in the neocortical local circuitry. In the present study, we examined the actions of VIP and VIP + norepinephrine (NE) on somatosensory cortical neuron responses to direct application of the putative transmitters acetylcholine (ACh) and gamma-aminobutyric acid (GABA). Spontaneous and transmitter-induced discharges of cortical neurons from halothane-anesthetized rats were monitored before, during and after VIP, NE and VIP + NE iontophoresis. In 57 VIP-sensitive cells tested, VIP application (5-70 nA) increased (n = 18), decreased (n = 36) or had biphasic actions (n = 3) on background firing rate. In a group of 20 neurons tested for NE + VIP, the combined effect of both peptide and bioamine was predominantly (70%) inhibitory. On the other hand, inhibitory and excitatory responses of cortical neurons to GABA (11 of 15 cases) and ACh (10 of 18 cases), respectively, were enhanced during VIP iontophoresis. Concomitant application of VIP and NE produced additive (n = 2) or more than additive (n = 3) enhancing effects on GABA inhibition. NE administration reversed or enhanced further VIP modulatory actions on ACh-induced excitation. These findings provide electrophysiological evidence that NE and VIP afferents may exert convergent influences on cortical neuronal responses to afferent synaptic inputs such that modulatory actions are anatomically focused within the cortex.

Distribution of Angiographic Vasospasm after Subarachnoid Hemorrhage: Implications for Diagnosis by Transcranial Doppler Ultrasonography

A study was undertaken to determine how frequently angiographic vasospasm occurs outside the normal access range of transcranial Doppler ultrasound in patients who have suffered a subarachnoid hemorrhage. Vasospasm located in the basal vessels is readily identifiable using transcranial Doppler ultrasound whereas spasm affecting the more distal, vertically oriented arteries is outside the standard detection range. It is therefore speculated that the sensitivity of the technique would be adversely affected by a high incidence of distal vasospasm. A total of 136 angiograms performed on 68 patients after a subarachnoid hemorrhage from anterior circulation aneurysms were reviewed to determine the typical distribution of vasospasm. Of the 40 cases that showed &gt;25% vessel narrowing, 50.0% had spasm restricted to the basal vessels, 42.5% had spasm involving both basal and distal segments, and 7.5% had spasm of the distal segments only. None of the patients with distal vasospasm alone developed delayed ischemic deficits. It is concluded that most patients with anterior circulation aneurysms who develop vasospasm will have involvement of the basal vessels, but a small number of patients may develop vasospasm only in distal vessels.