The non-decussating and decussating trigeminothalamic tracts in humans: A combination of connectome-based tractography and histological validation

BACKGROUND

Functional anatomical research proposed the existence of a bilateral trigeminal ascending system although the anatomy trajectories of the trigeminothalamic connections cranial to the pons remain largely elusive. This study therefore aimed to clarify the anatomical distributions of the trigeminothalamic connections in humans.

METHODS

Advanced deterministic tractography to an averaged template of diffusion tensor imaging data from 1065 subjects from the Human Connectome Project was used. Seedings masks were placed in Montreal Neurological Institute standard space by use of the BigBrain histological dataset. Waypoint masks of the sensory thalamus was obtained from the Brainnetome Atlas.

RESULTS

Tractography results were validated by use of the BigBrain histological dataset and Polarized Light Imaging microscopy. The trigeminothalamic tract bifurcated into a decussating ventral and a non-decussating dorsal tract. The ventral and dorsal tracts ascended to the contralateral thalamus and ipsilateral thalamus and reflected the ventral trigeminothalamic tract and the dorsal trigeminothalamic tract, respectively. The projection of the ventral trigeminothalamic tract and the dorsal trigeminothalamic tract to both thalami confirm the existence of a bilateral trigeminothalamic system in humans.

CONCLUSIONS

Because our study is strictly anatomical, no further conclusions can be drawn with regard to physiological functionality. Future research should explore if the dorsal trigeminothalamic tract and the ventral trigeminothalamic tract actually transmit signals from noxious stimuli, this offers potential in understanding and possibly treating neuropathology in the orofacial region.

The Untold Story of Occipital Nerve Stimulation in Patients With Cluster Headache: Surgical Technique in Relation to Clinical Efficacy

OBJECTIVES

Approximately one in every 1000 adults experiences cluster headache (CH). Although occipital nerve stimulation (ONS) appears encouraging in treatment for most patients with refractory CH, some patients do not reach adequate pain relief with ONS. A reason for failure of ONS might be anatomical variations and different surgical approaches. Therefore, an extensive literature analysis was performed, and cadaveric experimentation was combined with our clinical experience to provide a standardized proposal for ONS and obtain optimal management of patients with refractory CH.

MATERIALS AND METHODS

Data from 36 articles published between 1998 and 2023 were analyzed to retrieve information on the anatomical landmarks and surgical technique of ONS. For the cadaveric experimentation (N = 1), two electrodes were inserted from the region over the foramen magnum and projected toward the lower third of the mastoid process.

RESULTS

The existence of multiple approaches of ONS has been confirmed by the present analysis. Discrepancies have been found in the anatomical locations and corresponding landmarks of the greater and lesser occipital nerve. The surgical approaches differed in patient positioning, electrode placement, and imaging techniques, with an overall efficacy range of 35.7% to 90%.

CONCLUSIONS

Reports on the surgical approach of ONS remain contradictory, hence emphasizing the need for standardization. Only if all implanting physicians perform the ONS surgery using a standardized protocol, can future data be combined and outcomes compared and analyzed.

Intra- and interindividual attack frequency variability of chronic cluster headache

BACKGROUND

The lack of knowledge about the intra- and interindividual attack frequency variability in chronic cluster headache complicates power and sample size calculations for baseline periods of trials, and consensus on their most optimal duration.

METHODS

We analyzed the 12-week baseline of the ICON trial (occipital nerve stimulation in medically intractable chronic cluster headache) for: (i) weekly vs. instantaneous recording of attack frequency; (ii) intra-individual and seasonal variability of attack frequency; and (iii) the smallest number of weeks to obtain a reliable estimate of baseline attack frequency.

RESULTS

Weekly median (14.4 [8.2-24.0]) and instantaneous (14.2 [8.0-24.5]) attack frequency recordings were similar (p = 0.20; Bland-Altman plot). Median weekly attack frequency was 15.3 (range 4.2-140) and highest during spring (p = 0.001) compared to the other seasons. Relative attack frequency variability decreased with increasing attack frequency (p = 0.010). We tabulated the weekly attack frequency estimation accuracies compared to, and the associated deviations from, the 12-week gold standard for different lengths of the observation period.

CONCLUSION

Weekly retrospective attack frequency recording is as good as instantaneous recording and more convenient. Attack frequency is highest in spring. Participants with ≥3 daily attacks show less attack frequency variability than those with <3 daily attacks. An optimal balance between 90% accuracy and feasibility is achieved at a baseline period of seven weeks.The ICON trial is registered in ClinicalTrials.gov under number NCT01151631.

200 A randomized, placebo-controlled study of galcanezumab in patients with treatment-resistant migraine: double-blind results from CONQUER

Objective

CONQUER assessed galcanezumab efficacy and safety in patients with episodic or chronic migraine who had multiple migraine preventive treatment failures.

Methods

In this phase 3, double-blind study, patients (aged 18–75 years) met criteria for migraine, had 4–29 monthly migraine headache days, and 2–4 migraine preventive medication category failures in the past 10 years. Patients were randomized to receive galcanezumab 120mg/month (with 240-mg loading dose; N=232) or placebo (N=230). Primary endpoint: overall mean change from baseline in number of monthly migraine headache days across Months 1–3. Key secondary endpoints: ≥50%, ≥75%, or 100% reduction in monthly migraine headache days and change on Migraine-Specific Quality of Life-Role Function Restrictive domain.

Results

Galcanezumab-treated patients averaged 4.1 fewer monthly migraine headache days from a baseline of 13.4 versus placebo patients’ average of 1.0 fewer from a baseline of 13.0 (between-group difference 3.1; p<0.0001; 95%CI: -3.9, -2.3; effect size=0.72). Galcanezumab was superior to placebo on all key secondary endpoints and did not differ from placebo in terms of safety.

Conclusion

Galcanezumab was superior to placebo in preventive treatment of migraine and was safe and well tolerated in patients with previous failures to standard-of-care preventive treatments.

pain_andrew@lilly.com

Integrated multidisciplinary care in Parkinson's disease: a non-randomised, controlled trial (IMPACT)

BACKGROUND

A multidisciplinary approach is thought to be the best way to manage the motor and non-motor symptoms of Parkinson's disease, but how such care should be delivered is unknown. To address this gap in knowledge, we assessed the effectiveness of an integrated multidisciplinary approach compared with usual care.

METHODS

We recruited patients for our non-randomised controlled trial from six community hospitals in the Netherlands (two in regions where the integrated care intervention was available and four in control regions that administered usual care). Eligible patients were those with Parkinson's disease, aged 20-80 years, and without severe cognitive impairment or comorbidity. Patients in the intervention group were offered an individually tailored comprehensive assessment in an expert tertiary referral centre and subsequent referrals to a regional network of allied health professionals specialised in Parkinson's disease. Primary outcomes were activities of daily living (Academic Medical Center linear disability score [ALDS]) and quality of life (Parkinson's disease quality of life questionnaire [PDQL]) measured at 4, 6, and 8 months. Secondary outcomes included motor functioning (unified Parkinson's disease rating scale, part III [UPDRS III], at 4 months), caregiver burden (belastungsfragebogen Parkinson angehörigen-kurzversion [BELA-A-k] at 4 and 8 months), and costs (during whole study period). Primary analysis was by intention to treat and included scores over 4, 6, and 8 months, with correction for baseline score. The trial is registered at Clinicaltrials.gov, number NCT00518791.

FINDINGS

We recruited 301 patients (150 patients in the intervention group and 151 in the control group) between August, 2007, and December, 2009, of whom 285 completed follow-up (last follow-up was July, 2010). 101 (67%) patients in the intervention group visited the expert centre; 49 (33%) opted not to visit the expert centre. The average ALDS score from months 4, 6, and 8, with correction for baseline score, was greater in the intervention group than in the control group (difference 1·3 points, 95% CI -2·1 to 2·8; corresponding raw logit score difference 0·1, 95% CI 0·003 to 0·2) as was the average PDQL score (difference 3·0 points, 0·4 to 5·6). Secondary analysis with correction for baseline disease severity showed no differences between groups for ALDS (difference 0·9 points, 95% CI -0·6 to 2·4; corresponding raw logit score difference 0·1, -0·02 to 0·3) or PDQL (difference 1·7 points, -1·2 to 4·6). Secondary outcomes did not differ between groups (UPDRS III score difference 0·6 points, 95% CI -1·4 to 2·6; BELA-A-k score difference 0·8 points, -0·2 to 1·8; cost difference €742, -€489 to €1950).

INTERPRETATION

This integrated care approach offered only small benefits to patients with Parkinson's disease, and these disappeared after correction for baseline disease severity. These results suggest that different approaches are needed to achieve more substantial health benefits.

FUNDING

NutsOhra Foundation, Stichting Parkinson Nederland, National Parkinson Foundation.

Occipital nerve stimulation in medically intractable, chronic cluster headache. The ICON study: Rationale and protocol of a randomised trial

Background

About 10% of cluster headache patients have the chronic form. At least 10% of this chronic group is intractable to or cannot tolerate medical treatment. Open pilot studies suggest that occipital nerve stimulation (ONS) might offer effective prevention in these patients. Controlled neuromodulation studies in treatments inducing paraesthesias have a general problem in blinding. We have introduced a new design in pain neuromodulation by which we think we can overcome this problem.

Methods/design

We propose a prospective, randomised, double-blind, parallel-group international clinical study in medically intractable, chronic cluster headache patients of high- versus low-amplitude ONS. Primary outcome measure is the mean number of attacks over the last four weeks. After a study period of six months there is an open extension phase of six months. Alongside the randomised trial an economic evaluation study is performed.

Discussion

The ICON study will show if ONS is an effective preventive therapy for patients suffering medically intractable chronic cluster headache and if there is a difference between high- and low-amplitude stimulation. The innovative design of the study will, for the first time, assess efficacy of ONS in a blinded way.

EEG leading to the diagnosis of limbic encephalitis

Limbic encephalitis is characterized by subacute onset of short-term memory loss, seizures, sleep disturbances, as well as psychiatric and behavioral symptoms. A subgroup is associated with voltage-gated potassium channel antibodies (VGKC-Abs). In many cases, brain magnetic resonance imaging (MRI) demonstrates hyperintense areas in the medial part of the temporal lobe. Also, pleiocytosis is frequently found. In this study, we describe a 69-year-old man with VGKC-Abs limbic encephalitis with generalized tonic-clonic seizures, increasing memory deficits, visual hallucinations, depression, and severe insomnia. Brain MRI and cerebrospinal fluid (CSF) were normal, while the electroencephalogram (EEG) showed bilateral frontal and temporal intermittent rhythmic delta activity with disorganization and slowing of background activity, ultimately leading to the diagnosis of limbic encephalitis. The patient improved markedly after starting immunosuppressive therapy, both clinically and electrophysiologically. In addition to temporal lobe involvement on the brain MRI and CSF inflammation, we propose EEG abnormalities as an additional diagnostic criterion for limbic encephalitis.

The ParkinsonNet concept: development, implementation and initial experience

The quality and efficiency of allied health care in Parkinson's disease (PD) must be improved. We have developed the ParkinsonNet concept: a professional regional network within the catchment area of hospitals. ParkinsonNet aims to: (1) improve PD-specific expertise among allied health personnel, by training a selected number of therapists according to evidence-based guidelines; (2) enhance the accuracy of referrals by neurologists; (3) boost patient volumes per therapist, by stimulating preferred referral to ParkinsonNet therapists; and (4) stimulate collaboration between therapists, neurologists, and patients. We describe the procedures for developing a ParkinsonNet network. Our initial experience with this new concept is promising, showing an increase in PD-specific and a steady rise in the patient volume of individual therapists.

Evaluation of a Patient-Specific Index as an outcome measure for physiotherapy in Parkinson's disease

AIM

The aim of this paper was to develop and evaluate a patient-specific index for physiotherapy in Parkinson's disease (PSI-PD).

METHODS

In the PSI-PD, patients 1) select problematic activities out of a predefined list, with one self-report item; 2) rank selected items in order of importance; and 3) rate severity for each ranked item. To examine test-retest reliability, a cohort of patients was asked to complete the PSI-PD twice. Afterwards, validity was evaluated using a telephone interview.

RESULTS

The PSI-PD was completed twice by 81 patients. Test-retest agreement for the selection of activity limitations was 73% to 94%. Items ranked by patients were categorized into domains, of which gait, transfers and dexterity were rated most frequently (41%-70%). Test-retest agreement for ranked domains ranged from 74% to 82%. Interviews confirmed that the PSI-PD reliably identified problem areas.

CONCLUSIONS

The PSI-PD is a relevant, reliable and valid instrument to identify limitations in everyday activities that are important for both PD patients and physiotherapists.

Anticonvulsant drugs for migraine prophylaxis

BACKGROUND

Anticonvulsant drugs seem to be useful in clinical practice for the prophylaxis of migraine. This might be explained by a variety of actions of these drugs in the central nervous system that are probably relevant to the pathophysiology of migraine.

OBJECTIVES

To describe and assess the evidence from controlled trials on the efficacy and tolerability of anticonvulsants for preventing migraine attacks in adult patients with migraine.

SEARCH STRATEGY

We searched MEDLINE (from 1966 on) and the Cochrane Central Register of Controlled Trials (CENTRAL). Date of most recent search: April 2003. Additional information was gained from hand-searching specialist headache journals; correspondence with pharmaceutical companies, authors of reports, and experts in the field; and a wide variety of review articles and book chapters.

SELECTION CRITERIA

Studies were required to be prospective, controlled trials of self-administered drug treatments taken regularly to prevent the occurrence of migraine attacks and/or to reduce the intensity of those attacks.

DATA COLLECTION AND ANALYSIS

Studies were selected and data extracted by two independent reviewers. For migraine frequency data, standardized mean differences (SMDs) were calculated for individual studies and pooled across studies. For dichotomous data on significant reduction in migraine frequency, odds ratios (ORs) and numbers-needed-to-treat (NNTs) were similarly calculated. Adverse events were analyzed by calculating numbers-needed-to-harm (NNHs) for studies using similar agents.

MAIN RESULTS

Fifteen papers were included in the review. Of these, 14 reported trials comparing anticonvulsants with placebo, as follows: four trials of divalproex sodium, three trials of topiramate, two trials of sodium valproate, two trials of gabapentin, and one trial each of carbamazepine, clonazepam, and lamotrigine. One paper reported a trial of sodium valproate versus an active comparator, flunarizine, and one trial of divalproex sodium versus placebo included a comparison against propranolol, also an active comparator. Data from 2024 patients were considered. Analysis of data from eight trials (n = 841) demonstrates that anticonvulsants, considered as a class, reduce migraine frequency by about 1.4 attacks per 28 days as compared to placebo (SMD -0.60; 95% confidence interval [CI] -0.93 to -0.26). Data from 10 trials (n = 1341) show that anticonvulsants, considered as a class, also more than double the number of patients for whom migraine frequency is reduced by 50% or more, relative to placebo (OR 3.90; 95% CI 2.61 to 5.82; NNT 3.8; 95% CI 3.2 to 4.6). For seven trials of sodium valproate and divalproex sodium, NNHs for five clinically important adverse events ranged from 6.6 to 16.3. For the three trials of topiramate, NNHs for eight adverse events (100-mg dose) ranged from 2.4 to 32.9.

REVIEWERS' CONCLUSIONS

Anticonvulsants appear to be both effective in reducing migraine frequency and reasonably well tolerated. There is noticeable variation among individual agents, but there are insufficient data to know whether this is due to chance or variation in true efficacy. Neither clonazepam nor lamotrigine was superior to placebo (one trial each). Relatively few robust trials are available for agents other than sodium valproate/divalproex sodium. Two recently published and large trials of topiramate demonstrated reasonable efficacy, and one further trial of this agent is anticipated in the near future.

Might migraine damage the brain?

Recent debate concerning the interpretation of studies of regional cerebral blood flow in migraine has re-emphasized that cerebral ischaemia may occur during attacks of migraine with aura. In this article we suggest that the presence of ischaemia during attacks makes it possible that migraine with aura causes neuronal damage in the long term. We argue that damage is likely to occur in the primary visual cortex, given that a recent high-resolution rCBF study has found flow reductions confined to this area. Furthermore, we hypothesize that the extent to which rCBF is reduced in migraine with aura is sufficient to cause damage only to GABA-ergic inhibitory interneurons in layer IV of this cortex. In animal models, similar cells are known to be selectively vulnerable to damage as a result of hypoxic conditions. Evidence consistent with our hypothesis is provided by recent studies of visual function in migraine. Some clinical and pathophysiological implications of this hypothesis are discussed.