The gelastic seizures-hypothalamic hamartoma syndrome: facts, hypotheses, and perspectives

Hypothalamic hamartoma (HH) can be associated with a wide spectrum of epileptic conditions, ranging from a mild form with seizures characterized by urge to laugh and no cognitive involvement up to a catastrophic encephalopathy with early onset gelastic seizures (GS), precocious puberty, and mental retardation. Moreover, a refractory, either focal or generalized, epilepsy develops during the clinical course in nearly all the cases. Neurophysiologic and neuroimaging studies have demonstrated that HH itself generates GS and starts a process of secondary epileptogenesis responsible for refractory focal or generalized epilepsy. The intrinsic epileptogenicity of HH may be explained by the neurophysiological properties of small GABAergic, spontaneously firing HH neurons. Surgical ablation of HH can reverse epilepsy and encephalopathy. Gamma-knife radiosurgery and image-guided robotic radiosurgery seem to be useful and safe approaches for treatment, in particular of small HH. Here, we review this topic, based on literature reports and our personal observations. In addition, we discuss pathogenetic hypotheses and suggest new approaches to this intriguing issue.

Efficacy and toxicity of CyberKnife re-irradiation and "dose dense" temozolomide for recurrent gliomas

BACKGROUND

Stereotactic radiosurgery (SRS) can be a useful adjunct to the treatment of recurrent glioblastoma multiforme (GBM). Its combination with chemotherapy is attractive for the possible radiosensitization effect and cytotoxicity on tumor cells in distant areas. The aim of this study was to evaluate the efficacy and toxicity of CyberKnife SRS alone and combined with a "dose-dense" administration of temozolomide (TMZ) for recurrent GBM.

METHODS

Between July 2007 and July 2010, 23 patients underwent CyberKnife SRS. In 12 patients irradiation was combined with TMZ at 75 mg/m(2)/day for 21 days every 28 days. The median prescription dose in this group was 20 Gy (mean 20.7 ± 4 Gy) with a median number of fractions of 2. The median dose for the 11 patients who underwent SRS alone was 20 Gy (mean 19.9 ± 4.4 Gy; p = NS).

RESULTS

The median survival was 12 months for patients who underwent SRS/TMZ and 7 months for those who received SRS alone (p < 0.01). The 6-month progression-free survival (PFS) of the SRS/TMZ group was 66.7% vs. 18% for those who underwent SRS alone (p = 0.03). The median time to progression (TTP) was 7 months for patients who underwent SRS/TMZ and 4 months for those who underwent SRS alone (p = 0.01). Corticosteroid dependency was developed by most patients; radionecrosis was evident in one patient (4.3%) receiving TMZ. Grade 3 hematological toxicity was recorded in >40% of patients receiving chemotherapy.

CONCLUSIONS

The results suggest that Cyberknife re-treatments are relatively safe using selected dose/fraction schemes. The combination with TMZ improved patients' outcomes with OS and 6-month PFS that favorably compares with alternative treatments, but the incidence of major adverse effects was >40%. Further studies are warranted.

Non-resective surgery and radiosurgery for treatment of drug-resistant epilepsy

Epilepsy surgery is an effective treatment for properly selected patients with intractable seizures. However, many patients with medically intractable epilepsy are not excellent candidates for surgical resection of the epileptogenic zone. Due to recent advances in computer technology and bioengineering, several novel techniques are receiving increasing interest for their role in the care of people with epilepsy. Neuromodulation is an emerging surgical option to be used when conventional resective surgery is not indicated. We review the indications and expected outcomes of neuromodulatory treatments currently available for the treatment of refractory epilepsy, i.e., vagus nerve stimulation, deep brain stimulation, stereotactic radiosurgery, and multiple subpial transections.

Deep brain stimulation of subthalamic nuclei affects arm response inhibition in Parkinson's patients

The precise localizations of the neural substrates of voluntary inhibition are still debated. It has been hypothesized that, in humans, this executive function relies upon a right-lateralized pathway comprising the inferior frontal gyrus and the presupplementary motor area, which would control the neural processes for movement inhibition acting through the right subthalamic nucleus (STN). We assessed the role of the right STN, via a countermanding reaching task, in 10 Parkinson's patients receiving high-frequency electrical stimulation of the STN of both hemispheres (deep brain stimulation, DBS) and in 13 healthy subjects. We compared the performance of Parkinson's patients in 4 experimental conditions: DBS-ON, DBS-OFF, DBS-OFF right, and DBS-OFF left. We found that 1) inhibitory control is improved only when both DBS are active, that is, the reaction time to the stop signal is significantly shorter in the DBS-ON condition than in all the others, 2) bilateral stimulation of STN restores the inhibitory control to a near-normal level, and 3) DBS does not cause a general improvement in task-related motor function as it does not affect the length of the reaction times of arm movements, that is, in our experimental context, STN seems to play a selective role in response inhibition.

Radiosurgery for movement disorders

Stereotactic radiosurgery (SRS) has been proposed as an alternative treatment modality to pharmaceutical administration and deep brain stimulation (DBS) for patients suffering from movement disorders. Advanced neuroimaging is required for the identification of the functional structures and the accurate placement of the SRS lesion within the brain. Atlas-based techniques have also been used to aid delineation of the target during treatment planning. Maximum doses greater than 120 Gy have been suggested for controlling movement disorders. These high delivered doses and the irreversible character of SRS require accurate placement of the created lesions. In this article, achievements in the field of stereotactic radiosurgery, neuroimaging, and radiosurgical dose planning are reviewed, and an overview is provided of the clinical experience obtained to date in the radiosurgical treatment of movement disorders.

Stereotactic radiosurgery using CT cisternography and non-isocentric planning for the treatment of trigeminal neuralgia

OBJECTIVE

Frame-based radiosurgical rhizotomy has been shown in clinical studies to be effective for managing trigeminal neuralgia (TN). To date, however, only a small pilot study has been published for the frameless, image-guided CyberKnife system. We present our preliminary experience with 29 trigeminal neuralgia patients treated with the frameless CyberKnife using X-ray image-guided targeting, a novel CT method for target definition, and non-isocentric planning.

MATERIALS AND METHODS

All 29 patients failed previous medical therapy and 14 had undergone prior surgical procedures. CT iohexal cisternography was used to identify the 6- to 8-mm segment of nerve to be lesioned. The marginal dose ranged from 60 to 70 Gy (median 66.4 Gy) as defined at an average 79th percentile. The corresponding Dmax varied from 71.4 to 86.4 Gy (median 77.91 Gy).

RESULTS

After a median 10-month follow-up, 26 of 29 (90%) patients rated their pain control as excellent and 3 (10%) reported no improvement. Median time to improvement was 6 days. No or only minor progression in numbness was reported by 22 of 29 (76%) patients, 4 of 29 (14%) patients reported worsening, and 3 of 29 (10%) reported the onset of severe ipsilateral facial numbness. Two patients whose target volume inadvertently included the semi-lunar ganglion developed painful dysethesias in the distribution of their numbness.

CONCLUSION

Although the optimal dose and length of nerve to be lesioned are still being refined, this preliminary experience suggests that image-guided robotic radiosurgery can effectively lesion the trigeminal nerve. Further follow-up is needed to determine whether our method has advantages over the more commonly used procedure for radiosurgical trigeminal rhizotomy.

Computer aided robotic radiosurgery

Radiosurgery involves the precise delivery of sharply collimated high-energy beams of radiation to a distinct target volume along selected trajectories. Historically, accurate targeting required the application of a stereotactic frame, thus limiting the use of this procedure to single treatments of selected intracranial lesions. However, the scope of radiosurgery has undergone a remarkable broadening since the introduction of image-guided robotic radiosurgery. Recent developments in real-time image guidance provide an effective frameless alternative to conventional radiosurgery and allow both the treatment of lesions outside the skull and the possibility of performing hypofractionation. As a consequence, targets in the spine, chest and abdomen can now also be radiosurgically ablated with submillimetric precision. Meanwhile, the combination of image guidance, robotic beam delivery, and non-isocentric inverse planning can greatly enhance the conformality and homogeneity of radiosurgery. The aim of this article is to describe the technological basis of image-guided radiosurgery and provide a perspective on future developments. The current clinical usage of robotic radiosurgery will be reviewed with an emphasis on those applications that may represent a major shift in the therapeutic paradigm.

Role of stereotactic radiosurgery and fractionated stereotactic radiotherapy for the treatment of recurrent glioblastoma multiforme

Glioblastoma multiforme (GBM) is a devastating malignant brain tumor characterized by resistance to available therapeutic approaches and relentless malignant progression that includes widespread intracranial invasion, destruction of normal brain tissue, progressive disability, and death. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) are increasingly used in patients with recurrent GBM to complement traditional treatments such as resection, conventional external beam radiotherapy, and chemotherapy. Both SRS and fSRT are powerful noninvasive therapeutic modalities well suited to treat focal neoplastic lesions through the delivery of precise, highdose radiation. Although no randomized clinical trials have been performed, a variety of retrospective studies have been focused on the use of SRS and fSRT for recurrent GBMs. In addition, state-of-the-art neuroimaging techniques, such as MR spectroscopic imaging, diffusion tensor tractography, and nuclear medicine imaging, have enhanced treatment planning methods leading to potentially improved clinical outcomes. In this paper the authors reviewed the current applications and efficacy of SRS and fSRT in the treatment of GBM, highlighting the value of these therapies for recurrent focal disease.

Protecting venous structures during radiosurgery for parasagittal meningiomas

Symptomatic edema is a potential complication of meningioma radiosurgery. Parasagittal meningiomas are at a particular risk for symptomatic edema, suggesting a role for a venous occlusive complication. The authors sought to develop a strategy to optimize CyberKnife stereotactic radiosurgical treatment parameters to reduce the irradiation of the peritumoral venous system. Multislice CT venography with 3D reconstructions was performed and coregistered with thin-section, contrast-enhanced, volumetric MR images. The tumor and critical volumes were contoured on the MR images. Venous anatomical details obtained from the CT venographic study were then exported onto the MR imaging and fused MR imaging-CT study. Target and critical structure volumes and dosimetric parameters obtained with this method were analyzed. The authors found that reducing the irradiation of veins that course along the surface of the meningioma, which may be at risk for radiation-induced occlusion, is feasible in parasagittal meningioma radiosurgery without compromising other treatment parameters including conformality, homogeneity, and target coverage. Long-term follow-up is needed to assess the clinical validity of this treatment strategy.

[Locally recurrent rectal cancer. Our experience]

The aim of this study was to describe the personal experience in the treatment of 31 patients (19 males, 12 females) with local recurrence following surgery for rectal adenocarcinoma. The exeresis of recurrence was possible in 17 patients (6 Miles, 9 Hartmann, 1 re-resection, 1 transanal resection); of these, only 6 patients reported an improvement of the quality of life. Patients surgically treated and patients with recurrence inoperable and submitted to palliative treatment (colostomy, pain control, radio- and/or chemotherapy) showed similar survival rates.

Riluzole protects Huntington disease patients from brain glucose hypometabolism and grey matter volume loss and increases production of neurotrophins

PURPOSE

Huntington disease (HD) mutation increases gain-of-toxic functions contributing to glutamate-mediated excitotoxicity. Riluzole interferes with glutamatergic neurotransmission, thereby reducing excitotoxicity, enhancing neurite formation in damaged motoneurons and increasing serum concentrations of BDNF, a brain cortex neurotrophin protecting striatal neurons from degeneration.

METHODS

We investigated metabolic and volumetric differences in distinct brain areas between 11 riluzole-treated and 12 placebo-treated patients by MRI and (18)F-fluoro-2-deoxy-D-glucose (FDG) PET scanning, according to fully automated protocols. We also investigated the influence of riluzole on peripheral growth factor blood levels.

RESULTS

Placebo-treated patients showed significantly greater proportional volume loss of grey matter and decrease in metabolic FDG uptake than patients treated with riluzole in all cortical areas (p<0.05). The decreased rate of metabolic FDG uptake correlated with worsening clinical scores in placebo-treated patients, compared to those who were treated with riluzole. The progressive decrease in metabolic FDG uptake observed in the frontal, parietal and occipital cortex correlated linearly with the severity of motor scores calculated by Unified Huntington Disease Rating Scale (UHDRS-I) in placebo-treated patients. Similarly, the rate of metabolic changes in the frontal and temporal areas of the brain cortex correlated linearly with worsening behavioural scores calculated by UHDRS-III in the placebo-treated patients. Finally, BDNF and transforming growth factor beta-1 serum levels were significantly higher in patients treated with riluzole.

CONCLUSION

The linear correlation between decreased metabolic FDG uptake and worsening clinical scores in the placebo-treated patients suggests that FDG-PET may be a valuable procedure to assess brain markers of HD.