Franz Riederer

NETWORK ATROPHY IN TEMPORAL LOBE EPILEPSY: A VOXEL-BASED MORPHOMETRY STUDY

NETWORK ATROPHY IN TEMPORAL LOBE EPILEPSY: A VOXEL-BASED MORPHOMETRY STUDY To the Editor: We read the article by Riederer at al.1 with interest. The authors confirmed previous findings on mesial temporal lobe epilepsy (mTLE) showing that hippocampal atrophy is associated with a well-defined network of extrahippocampal gray matter loss. They also demonstrated that cryptogenic temporal lobe epilepsy (cTLE) is associated with a pattern of gray matter atrophy.2-4 Their results indicate that there are subtle differences in the anatomic distribution of damage in patients with mTLE compared to those with cTLE. The cTLE and mTLE groups had varying levels of epilepsy severity yet both groups exhibited extrahippocampal atrophy and the pattern in each group was unique. Since VBM traditionally relies on the comparison of means of gray matter volume across different groups, reproducible findings on mTLE may indicate that patients with mTLE comprise a homogenous group. In comparison, patients with cTLE are likely more heterogeneous with outliers having pronounced brain damage. This may explain why the distribution of atrophy in cTLE is scattered across different brain areas and why previous studies have been unable to consistently observe differences between cTLE and controls. What is the primary cause of extrahippocampal atrophy in TLE? Two common hypotheses are that brain atrophy in patients with TLE may be due to excitotoxic effect from seizures as they spread. Alternatively, it may be due to remote deafferentation from loss of hippocampal connections. Riederer et al. suggest that hippocampal atrophy alone is not responsible for causing brain atrophy yet plays a partial role in shaping the location and extent of atrophy. Further studies are needed to replicate these findings while considering the severity of epilepsy. It is possible that both recurrent seizures and hippocampal atrophy are necessary to generate a diffuse and homogeneous pattern of extrahippocampal atrophy.

Grey matter changes associated with medication-overuse headache: correlations with disease related disability and anxiety.

Abstract Objectives. Medication-overuse headache (MOH) is associated with psychiatric comorbidities. Neurobiological similarities to substance dependence have been suggested. This study investigated grey matter changes, focussing on pain and reward systems. Methods. Using voxel-based morphometry, structural MRIs were compared between 29 patients with both, MOH and migraine, according to International Headache Society criteria, and healthy controls. The Migraine Disability Assessment (MIDAS) score was used. Anxiety and depression were screened for with the Hospital Anxiety and Depression Scale (HADS) and confirmed by a psychiatrist, using the Mini International Neuropsychiatric Interview. Results. Nineteen patients (66%) had a present or past psychiatric disorder, mainly affective (N = 11) and anxiety disorders (N = 8). In all patients a significant increase of grey matter volume (GMV) was found in the periaqueductal grey matter of the midbrain, which correlated positively with the MIDAS and the HADS-anxiety subscale. A GMV increase was found bilaterally in the thalamus, and the ventral striatum. A significant GMV decrease was detected in frontal regions including orbitofrontal cortex, anterior cingulate cortex, the left and right insula, and the precuneus. Conclusion. These findings are consistent with dysfunction of antinociceptive systems in MOH, which is influenced by anxiety. Dysfunction of the reward system may be a neurobiological basis for dependence in a subgroup of MOH patients.

Decrease of Gray Matter Volume in the Midbrain is Associated with Treatment Response in Medication-Overuse Headache: Possible Influence of Orbitofrontal Cortex

Patients with chronic daily headache and overuse of analgesics, triptans, or other acute headache compounds, are considered to suffer from medication-overuse headache (MOH). This implies that medication overuse is the cause of headache chronification. It remains a key question why only two-thirds of patients with chronic migraine-like headache and overuse of pain medication improve after detoxification, whereas the remainder continue to have chronic headache. In the present longitudinal MRI study, we used voxel-based morphometry to investigate gray matter changes related to medication withdrawal in a group of humans with MOH. As a main result, we found that only patients with significant clinical improvement showed a significant decrease of previously increased gray matter in the midbrain including periaqueductal gray matter and nucleus cuneiformis, whereas patients without improvement did not. Patients without treatment response had less gray matter in the orbitofrontal cortex. Another striking result is the correlation of treatment response with the amount of orbitofrontal gray matter. Thus, we demonstrate adaptive gray matter changes within the pain modulatory system in patients with MOH who responded to detoxification, probably reflecting neuronal plasticity. Decreased gray matter in the orbitofrontal cortex at baseline may be predictive of poor response to treatment.

Acute confusional migraine: our knowledge to date

Acute confusional migraine (ACM) is a rare migraine variant, affecting children and adolescents, as well as adults. Between 0.45 and 7.8% of children with migraine present with ACM, but the disorder may well be underdiagnosed. ACM is an exclusion diagnosis and some dangerous causes of confusion (e.g., epilepsy, ischemia, hemorrhagia, neoplasm, intoxication and encephalitis) should be ruled out. The confusional state often manifests with a wide diversity of cortical dysfunctions, such as speech difficulties, increased alertness, agitation and amnesia. Exact history taking, clinical examination, and laboratory, radiological and electroencephalographical findings lead the practitioner towards the diagnosis. Approximately half of the cases may be triggered by mild head trauma. Transient global amnesia is an important differential diagnosis, possibly caused by similar pathophysiological mechanisms. The exact pathomechanism remains unclear, with the common hypothesis comprising of the confusional state as a complex aura phenomenon, in which the cortical spreading depression wave reaches not only the occipital, but also the temporal, parietal and frontal cortex, as well as the brainstem and the hippocampi, leading to transient hypoperfusion and dysfunction of these brain areas.

Efficacy and safety of 121 injections of the greater occipital nerve in episodic and chronic cluster headache

Introduction: Infiltration of the greater occipital nerve (GON) with local anaesthetics and corticosteroids is a treatment option for cluster headache. Methods: We retrospectively analysed the efficacy and safety of 121 GON injections in 60 patients with episodic or chronic cluster headache over a period of 4 years. Results: Almost 80% of the infiltrations were at least partially effective (reduction of attack frequency, duration or severity) and 45% resulted in a complete response (no further attacks). The effect was maintained for 3.5 weeks on average in chronic cluster headache. In episodic cluster headache, the effect lasted for most of the bout. In 18 infiltrations, transient side effects were reported, such as local pain, steroid effects (facial oedema, sleeping disorders, acne), bradycardia or syncope. Conclusion: Our data show that GON infiltration is a valuable and safe option in the clinical setting to treat patients suffering from cluster headache, especially for the episodic form of the disorder.

Familial occipital and nervus intermedius neuralgia in a Swiss family

Familial trigeminal neuralgia has been reported in 1–2% of cases consistent with an autosomal dominant inheritance. We present a Swiss family with several members suffering from occipital and nervus intermedius neuralgia alone or in combination. We suggest that peripheral sensory anastomoses or central convergence of afferent pathways could explain neuralgia affecting two cranial nerves. The pedigree has two main characteristics: (1) affected individuals in two generations and (2) in the first generation the father is affected, in the second generation all women are affected, and none of the men. This is suggestive of an X-linked dominant or an autosomal dominant mode of inheritance.

Confusional migraine is an adult as well as a childhood disease

Background: Acute confusional migraine (ACM) is considered a rare migraine variant primarily seen in children and adolescents. Patients and Methods: We present a series of eight adults and two adolescents suffering from migraine attacks associated with transient confusional states. Results: Eight patients reported two or more such attacks. One of them reported mild head trauma in the past. One patient reported mild head trauma as a possible trigger. Further investigations were unremarkable in all patients and did not suggest underlying structural abnormalities, epilepsy or cerebrovascular disease. In none of these patients did we find another cause to explain the observed phenomenon. Conclusions: Based on this series of patients, we suggest expanding the concept of confusional migraine from the paediatric population to adults. The temporal course of the confusion as well as the association with visual and other aura symptoms suggest cortical spreading depression as the underlying pathophysiology.

Pain modulation is affected differently in medication-overuse headache and chronic myofascial pain – A multimodal MRI study

Background Neuroimaging studies revealed structural and functional changes in medication-overuse headache (MOH), but it remains unclear whether similar changes could be observed in other chronic pain disorders. Methods In this cross-sectional study, we investigated functional connectivity (FC) with resting-state functional magnetic resonance imaging (fMRI) and white matter integrity using diffusion tensor imaging (DTI) to measure fractional anisotropy (FA) and mean diffusivity (MD) in patients with MOH (N = 12) relative to two control groups: patients with chronic myofascial pain (MYO; N = 11) and healthy controls (CN; N = 16). Results In a data-driven approach we found hypoconnectivity in the fronto-parietal attention network in both pain groups relative to CN (i.e. MOH < CN and MYO < CN). In contrast, hyperconnectivity in the saliency network (SN) was detected only in MOH, which correlated with FA in the insula. In a seed-based analysis we investigated FC between the periaqueductal grey (PAG) and all other brain regions. In addition to overlapping hyperconnectivity seen in patient groups (relative to CN), MOH had a distinct connectivity pattern with lower FC to parieto-occipital regions and higher FC to orbitofrontal regions compared to controls. FA and MD abnormalities were mostly observed in MOH, involving the insula. Conclusions Hyperconnectivity within the SN along with associated white matter changes therein suggest a particular role of this network in MOH. In addition, abnormal connectivity between the PAG and other pain modulatory (frontal) regions in MOH are consistent with dysfunctional central pain control.

Familial neuralgia of occipital and intermedius nerves in a Chinese family

Cranial nerve neuralgia usually occurs sporadically. Nonetheless, familial cases of trigeminal neuralgia are not uncommon with a reported incidence of 1–2%, suggestive of an autosomal dominant inheritance. In contrast, familial occipital neuralgia is rarely reported with only one report in the literature. We present a Chinese family with five cases of occipital and nervus intermedius neuralgia alone or in combination in three generations. All persons afflicted with occipital neuralgia have suffered from paroxysmal ‘electric wave’-like pain for years. In the first generation, the father (index patient) was affected, in the second generation all his three daughters (with two sons spared) and in the third generation a daughter’s male offspring is affected. This familial pattern suggests an X-linked dominant or an autosomal dominant inheritance mode.

Postoperative hemicrania continua-like headache - a case series

BackgroundHemicrania continua (HC) is a rare chronic headache disorder, typically accompanied by cranial autonomic features and responding to therapeutic doses of indomethacin. The pathophysiology of hemicrania continua is not fully understood.FindingsWe report a series of three patients who developed a continuous hemicranial headache after cranial surgery. Each case presented a similar phenotype of continuous half-sided headache, cranial autonomic symptoms with exacerbations (2/3), and a response to indomethacin.ConclusionThe biology of hemicrania continua may be activated post-craniotomy just as can be seen with other primary headache disorders.