Percutaneous approach to the foramen ovale: an anatomical study of the extracranial trajectory with the incorrect trajectories to be avoided

OBJECTIVE

Meckel's Cave may be accessed percutaneously through the foramen ovale (FO). Detailed knowledge of the region's anatomical surroundings is invaluable in improving target accuracy and preventing complications with this approach. The approach has been used in the treatment of trigeminal neuralgia as well as in performing biopsies of lesions located in the parasellar region, described formerly by the senior author (M.S.). A comprehensive cadaveric study of the region traversed by needle is thus presented.

MATERIALS AND METHODS

Three cadaveric heads (six sides) were fixed in formaldehyde and injected with latex. A detailed description of the regional anatomical needle trajectories was performed.

RESULTS

An "inverted pyramid" subdivided into three segments is described. The inferior third begins at cutaneous penetration and ends at the parotid duct (PD). The middle third extends from the PD to the lateral pterygoid muscle (LPM). The superior third starts from the LPM and ends at the FO. The main vascular anatomical variation was with regard to the maxillary artery (MA). In half of the cases, the MA traveled though the middle of the pyramid and in the other half through the upper third.

CONCLUSIONS

Although widely used, the FO approach carries risks. Special attention is warranted when the needle traverses the upper third of the pyramid to avoid the variant course of the MA. Image-guided techniques and detailed anatomical knowledge are necessary to expand the use of this route not just for approach to lesions within the parasellar and upper third of the petroclival region but also to lesions invading the infratemporal fossa.

Non-motor dopamine withdrawal syndrome after surgery for Parkinson's disease: predictors and underlying mesolimbic denervation

Apathy has been reported to occur after subthalamic nucleus stimulation, a treatment of motor complications in advanced Parkinson's disease. We carried out a prospective study of the occurrence of apathy and associated symptoms, predictors and mechanisms in the year following subthalamic stimulation. Dopamine agonist drugs were discontinued immediately after surgery and levodopa was markedly reduced within 2 weeks. Apathy and depression were assessed monthly, using the Starkstein apathy scale and the Beck Depression Inventory. Dopamine agonists were re-introduced if patients developed apathy or depression. Preoperative non-motor fluctuations were evaluated using the Ardouin Scale. Depression, apathy and anxiety were evaluated both on and off levodopa. Analysis of predictors of apathy was performed using a Cox proportional hazard model. Twelve patients who developed apathy and a control group of 13 patients who did not underwent [11C]-raclopride positron emission tomography scanning before and after oral intake of methylphenidate. In 63 patients with Parkinson's disease treated with subthalamic stimulation, dopaminergic treatment was decreased by 82% after surgery. Apathy occurred after a mean of 4.7 (3.3-8.2) months in 34 patients and was reversible in half of these by the 12-month follow-up. Seventeen patients developed transient depression after 5.7 (4.7-9.3) months and these fell into the apathy group with one single exception. At baseline, fluctuations in depression, apathy and anxiety scores were greater in the group with apathy. Fluctuations in apathy, depression and anxiety ratings during a baseline levodopa challenge were also significant predictors of postoperative apathy in univariate analysis, but not motor and cognitive states or the level of reduction of dopaminergic medication. The multivariate model identified non-motor fluctuations in everyday life and anxiety score during the baseline levodopa challenge as two independent significant predictors of postoperative apathy. Without methylphenidate, [11C]-raclopride binding potential values were greater in apathetic patients bilaterally in the orbitofrontal, dorsolateral prefrontal, posterior cingulate and temporal cortices, left striatum and right amygdala, reflecting greater dopamine D2/D3 receptor density and/or reduced synaptic dopamine level in these areas. The variations of [11C]-raclopride binding potential values induced by methylphenidate were greater in non-apathetic patients in the left orbitofrontal cortex, dorsolateral prefrontal cortex, thalamus and internal globus pallidus and bilaterally in the anterior and posterior cingulate cortices, consistent with a more important capacity to release dopamine. Non-motor fluctuations are related to mesolimbic dopaminergic denervation. Apathy, depression and anxiety can occur after surgery as a delayed dopamine withdrawal syndrome. A varying extent of mesolimbic dopaminergic denervation and differences in dopaminergic treatment largely determine mood, anxiety and motivation in patients with Parkinson's disease, contributing to different non-motor phenotypes.

Emergence of bluetongue serotypes in Europe, part 2: the occurrence of a BTV-11 strain in Belgium

An EDTA-blood sample from a cow without clinical signs, which gave early birth to a newborn calf that died soon after delivery, was shown to be positive for bluetongue virus (BTV)-RNA using a group-specific real-time RT-PCR (RT-qPCR). In-house serotype-specific RT-qPCR assays for bluetongue virus serotype 1 (BTV-1), -6 and -8 all gave negative results. Subsequent assays were carried out using conventional (gel-based) RT-PCR primers for all 25 BTV serotypes and only two primer sets, both specific for BTV-11, gave bands of the expected size. The cDNAs generated were sequenced and comparisons of the genome segment 2 sequence with that of the modified 'live' vaccine strain of BTV-11 from South Africa showed 100% identity. A survey of all ruminants in a 1-km area around the first positive farm using a BTV-11 serotype-specific RT-qPCR revealed five other holdings with in total nine BTV-11 positive animals. A cross-sectional monitoring of dairy cattle in Belgium showed an overall prevalence of 3.8% on herd level and 0.2% on animal level. A BTV-11 has been introduced into the Belgian cattle herd during the 2008 vector season. The source of the infection and the way by which the virus was introduced are unknown.

Safety and efficacy of deep brain stimulation in refractory cluster headache: a randomized placebo-controlled double-blind trial followed by a 1-year open extension

Chronic cluster headache (CCH) is a disabling primary headache, considering the severity and frequency of pain attacks. Deep brain stimulation (DBS) has been used to treat severe refractory CCH, but assessment of its efficacy has been limited to open studies. We performed a prospective crossover, double-blind, multicenter study assessing the efficacy and safety of unilateral hypothalamic DBS in 11 patients with severe refractory CCH. The randomized phase compared active and sham stimulation during 1-month periods, and was followed by a 1-year open phase. The severity of CCH was assessed by the weekly attacks frequency (primary outcome), pain intensity,sumatriptan injections, emotional impact (HAD) and quality of life (SF12). Tolerance was assessed by active surveillance of behavior, homeostatic and hormonal functions.During the randomized phase, no significant change in primary and secondary outcome measures was observed between active and sham stimulation. At the end of the open phase, 6/11 responded to the chronic stimulation(weekly frequency of attacks decrease [50%), including three pain-free patients. There were three serious adverse events, including subcutaneous infection, transient loss of consciousness and micturition syncopes. No significant change in hormonal functions or electrolytic balance was observed. Randomized phase findings of this study did not support the efficacy of DBS in refractory CCH, but open phase findings suggested long-term efficacy in more than 50% patients, confirming previous data, without high morbidity. Discrepancy between these findings justifies additional controlled studies (clinicaltrials.gov number NCT00662935).

Is exposure of the superior sagittal sinus necessary in the interhemispheric approach?

OBJECTIVE

Techniques for anterior interhemisperic craniotomy vary in respect to the degree of exposure of the superior sagittal sinus (SSS). The aim of this anatomic study is to quantify the increase in the angle of view gained by wide exposure and retraction of the SSS.

METHODS

The anterior interhemispheric approach was performed in 10 cadaveric specimens with and without complete exposure and retraction of the SSS. Prespecified anatomic targets within the depth of the surgical field were used to calculate the angle of view.

RESULTS

Complete exposure of the SSS in the anterior interhemispheric approach, increased the angle of view from 20.6 +/- 3 to 26.8 degrees, using the A4-A5 junction as a deep anatomic target (P = 0.008). When the free edge of the falx was considered as a deep anatomic target, complete exposure of the SSS increased the working angle from 34 +/- 3.14 to 42.1 +/- 4 (P = 0.0004).

CONCLUSION

In this study, we demonstrate a significant increase in the angle of view after complete exposure of the SSS, targeting either deep (anterior cerebral artery) or more shallow structures (free falx edge).

Description of sulcal organization of the insular cortex

PURPOSE

To study the morphology of the gyri and sulci of the insular region.

MATERIALS AND METHODS

This study examined 20 formalin-fixed cerebral hemispheres (10 right and 10 left). Observations described: the peri-insular sulci, anatomical variations in the insular sulci and gyri, and the relationships between the central insular sulcus and the central cerebral sulcus and the anatomy of the insular arteries.

RESULTS

Each insula had a trapezoid shape, surrounded by four peri-insular sulci (anterior, superior, posterior, and inferior). We differentiated the posterior peri-insular sulcus from the inferior peri-insular sulcus. These two sulci have two different axes separated by a clear angle. The central insular sulcus divides the insula into two parts. The anterior insula includes three short gyri and the anterior insular pole. The posterior insula includes two long gyri and the posterior insular pole. This structure defines two intra-insular opercula. In 60% of cases, the superior extremity of the central insular sulcus is in direct continuity with the inferior extremity of the cerebral central sulcus. The superior branch of the middle cerebral artery supplies the majority of the anterior insular gyri, and the inferior branch supplies the majority of the posterior insular gyri.

CONCLUSIONS

This study details the morphology of each insular structure (gyri, sulci and poles), data which could facilitate surgical access to this deep cortical area and assist in future work correlating anatomy with function.

Bilateral pallidal deep brain stimulation for the treatment of patients with dystonia-choreoathetosis cerebral palsy: a prospective pilot study

BACKGROUND

Cerebral palsy (CP) with dystonia-choreoathetosis is a common cause of disability in children and in adults, and responds poorly to medical treatment. Bilateral pallidal deep brain stimulation (BP-DBS) of the globus pallidus internus (GPi) is an effective treatment for primary dystonia, but the effect of this reversible surgical procedure on dystonia-choreoathetosis CP, which is a subtype of secondary dystonia, is unknown. Our aim was to test the effectiveness of BP-DBS in adults with dystonia-choreoathetosis CP.

METHODS

We did a multicentre prospective pilot study of BP-DBS in 13 adults with dystonia-choreoathetosis CP who had no cognitive impairment, little spasticity, and only slight abnormalities of the basal ganglia on MRI. The primary endpoint was change in the severity of dystonia-choreoathetosis after 1 year of neurostimulation, as assessed with the Burke-Fahn-Marsden dystonia rating scale. The accuracy of surgical targeting to the GPi was assessed masked to the results of neurostimulation. Analysis was by intention to treat.

FINDINGS

The mean Burke-Fahn-Marsden dystonia rating scale movement score improved from 44.2 (SD 21.1) before surgery to 34.7 (21.9) at 1 year post-operatively (p=0.009; mean improvement 24.4 [21.1]%, 95% CI 11.6-37.1). Functional disability, pain, and mental health-related quality of life were significantly improved. There was no worsening of cognition or mood. Adverse events were related to stimulation (arrest of the stimulator in one patient, and an adjustment to the current intensity in four patients). The optimum therapeutic target was the posterolateroventral region of the GPi. Little improvement was seen when the neurostimulation diffused to adjacent structures (mainly to the globus pallidus externus [GPe]).

INTERPRETATION

Bilateral pallidal neurostimulation could be an effective treatment option for patients with dystonia-choreoathetosis CP. However, given the heterogeneity of motor outcomes and the small sample size, results should be interpreted with caution. The optimum placement of the leads seemed to be a crucial, but not exclusive, factor that could affect a good outcome.

FUNDING

National PHRC; Cerebral Palsy Foundation: Fondation Motrice/APETREIMC; French INSERM Dystonia National Network; Medtronic.

[Structural anatomy of cranial nerves (V, VII, VIII, IX, X)]

This study reports a review of the literature on the structural anatomy of the Vth, VIIth, VIIIth, IXth, and Xth cranial nerves, known to harbor dysfunction syndromes in humans. Because these dysfunctions are hypothesized to be caused by neurovascular conflicts at the root entry/exit zone and the transitional zone between central and peripheral myelinization, this investigation focused on the study and description of this junction. All the cranial nerves, except the optic and olfactory nerves, which are considered to be more a direct expansion of the central nervous system, have a transitional zone between central myelin (coming from oligodendrocytes) and peripheral myelin (produced by Schwann cells). The human studies reported in the literature argue in favor of a dome-shaped transitional zone directed to the periphery. It seems that this junctional region is situated more peripherally in sensory nerves than in motor nerves. The transitional zone is situated very peripherally for the cochlear and vestibular nerves, and on the contrary very close to its exit from the brain stem for the facial nerve.

[Functional anatomy of the cochlear nerve and the central auditory system]

The auditory pathways are a system of afferent fibers (through the cochlear nerve) and efferent fibers (through the vestibular nerve), which are not limited to a simple information transmitting system but create a veritable integration of the sound stimulus at the different levels, by analyzing its three fundamental elements: frequency (pitch), intensity, and spatial localization of the sound source. From the cochlea to the primary auditory cortex, the auditory fibers are organized anatomically in relation to the characteristic frequency of the sound signal that they transmit (tonotopy). Coding the intensity of the sound signal is based on temporal recruitment (the number of action potentials) and spatial recruitment (the number of inner hair cells recruited near the cell of the frequency that is characteristic of the stimulus). Because of binaural hearing, commissural pathways at each level of the auditory system and integration of the phase shift and the difference in intensity between signals coming from both ears, spatial localization of the sound source is possible. Finally, through the efferent fibers in the vestibular nerve, higher centers exercise control over the activity of the cochlea and adjust the peripheral hearing organ to external sound conditions, thus protecting the auditory system or increasing sensitivity by the attention given to the signal.

Bilateral subthalamic nucleus stimulation in advanced Parkinson's disease: five year follow-up

OBJECTIVE

To assess the long-term efficacy and safety of bilateral subthalamic nucleus (STN) stimulation in patients with advanced Parkinson's disease (PD).

METHODS

42 consecutive patients with idiopathic PD treated with bilateral STN stimulation were enrolled. Parkinsonian status, medication intake and neuropsychological evaluation were assessed preoperatively and at 1 and 5 years postoperatively in on and off medication/on and off stimulation conditions.

RESULTS

23 patients could be followed-up 5 years after surgery. In the remaining cases, 5 died, 1 could not be assessed because of device removal for infection, 1 decided not to be stimulated, and 11 were lost of follow-up (one because of a liver carcinoma and the others because they refused the formal four conditions of assessment). STN stimulation reduced the UPDRS motor score by 55 % compared to baseline in the off-medication conditions. Tremor, rigidity, bradykinesia, postural stability, and gait improved by 74 %, 66 %, 59 %, 17 % and 37 %, respectively. UPDRS part II scores were reduced by 38 %. The dopaminergic treatment daily dose was reduced by 54.4 % after surgery. Axial dopa-unresponsive signs worsened in some patients. Among the 42 initial patients we observed the following: 2 brain hemorrhages, 3 infections of the device, 2 phlebitis and 1 pulmonary embolism. In addition, 2 patients needed a repositioning of the electrode. Among the 23 patients followed at 5 years, long lasting side effects consisted in dysarthria (56 %), depression (39 %), eyelid opening apraxia (30.4 %) and apathy (4.3 %).

CONCLUSIONS

Our data confirm that bilateral STN stimulation is beneficial in the long-term for PD patients but does not prevent disease progression and the occurence of axial levodopa unresponsive signs in some patients.

Pain relief by rTMS: differential effect of current flow but no specific action on pain subtypes

OBJECTIVES

To assess, against placebo, the pain-relieving effects of high-rate repetitive transcranial magnetic stimulation (rTMS) on neuropathic pain.

METHODS

Double-blind, randomized, cross-over study of high-rate rTMS against placebo in 28 patients. The effect of a change in coil orientation (posteroanterior vs lateromedial) on different subtypes of neuropathic pain was further tested in a subset of 16 patients. Pain relief was evaluated daily during 1 week.

RESULTS

High-frequency, posteroanterior rTMS decreased pain scores significantly more than placebo. Posteroanterior rTMS also outmatched placebo in a score combining subjective (pain relief, quality of life) and objective (rescue drug intake) criteria of treatment benefit. Changing the orientation of the coil from posteroanterior to lateromedial did not yield any significant pain relief. The analgesic effects of posteroanterior rTMS lasted for approximately 1 week. The pain-relieving effects were observed exclusively on global scores reflecting the most distressing type of pain in each patient. Conversely, rTMS did not modify specifically any of the pain subscores that were separately tested (ongoing, paroxysmal, stimulus-evoked, or disesthesic pain).

CONCLUSIONS

Posteroanterior repetitive transcranial magnetic stimulation (rTMS) was more effective than both placebo and lateromedial rTMS. When obtained, pain relief was not specific of any particular submodality, but rather reduced the global pain sensation whatever its type. This is in accord with recent models of motor cortex neurostimulation, postulating that its analgesic effects may derive in part from modulation of the affective appraisal of pain, rather than a decrease of its sensory components.