Psychophysiological aspects of voluntary skilled movement after stroke: a follow-up study

OBJECTIVES

The aim of the study was to follow the psychophysiological evolution of a self-paced voluntary skilled movement in hemiparetic subjects after ischemic stroke by means of a skilled performance task (SPT). The task consisted in starting a sweep of an oscilloscope trace by pushing one button with the left index finger (trigger point), and in stopping it within a central area on the oscilloscope screen, between 40 and 60 ms (correct performance) after the start of the sweep, by pushing the other button with the right index finger. A SPT yields a considerable amount of information on the electrophysiological components, which reflect pre-programming activity (Bereitschaftspotential--BP), control strategies (Skilled Performance Positivity--SPP) and behavioural response (Correct Performances). The study was also aimed at detecting any longitudinal changes in the psychophysiological pattern, as evaluated by the clinical examination and specific motility scales, that parallel motor recovery.

METHODS

Movement related potentials (MRPs) were recorded in 12 control subjects and 9 patients in the acute phase, before the start of neurorehabilitation (time 0), when the patients were able to execute an index finger press with the affected hand. The patients (mean age = 62.33 years, SD = 8.17) presented a mild to moderate central arm paresis caused by a first-ever unilateral supratentorial and subcortical ischemic lesion. The subsequent recordings were carried out respectively 3, 9 and 12 months later.

RESULTS

At the first recording, hemiparetic patients achieved a significantly lower percentage of correct performances and had a lower BP amplitude than controls (p < 0.001); SPP was absent. The number of correct performances did not improve significantly during the subsequent recordings. BP amplitude showed a mild increase in the second, third and fourth recordings (p < 0.05), while SPP amplitude revealed a slight improvement at the second and a marked improvement at the third and fourth recordings, when there was no longer a statistically significant difference from controls.

CONCLUSIONS

Our findings point to an early recovery of pre-programming activity and a delayed improvement in control activity. The delayed development of control activity in the absence of procedural learning, i.e. skill learning through practice, forces patients to exploit attentional strategies to compensate for their procedural learning impairment. SPT shows that the efficacy of physical therapy aimed at motor ability recovery in hemiparetic patients does not keep up with the slow recovery process of an automatic motor level.

Reduced habituation of trigeminal reflexes in patients with episodic cluster headache during cluster period

A growing body of evidence supports the pivotal role of the hypothalamus in the pathophysiology of cluster headache (CH). On the basis of animal studies, it has been suggested that a hypothalamic dysfunction can lead to a habituation deficit of brainstem reflex responses, as result of a stress-like condition. Taking into account these findings, we tested the hypothesis that habituation of brainstem reflexes may be impaired in CH patients. The habituation phenomenon of the late components (R2 and R3) of the blink reflex was studied in 27 CH patients during the cluster period, in 22 migraine patients interictally and in 20 control subjects. A significant habituation deficit in the R2 and R3 components was found in CH compared with both controls and migraineurs. The lack of habituation in CH, more pronounced than in migraine, points to abnormal processing of sensory stimuli at the trigeminal level that could be driven by hypothalamic dysfunction during the cluster period.

Is the cerebral cortex hyperexcitable or hyperresponsive in migraine?

Although migraineurs appear in general to be hypersensitive to external stimuli, they maybe also have increased daytime sleepiness and complain of fatigue. Neurophysiological studies between attacks have shown that for a number of different sensory modalities the migrainous brain is characterised by a lack of habituation of evoked responses. Whether this is due to increased cortical hyperexcitability, possibly due to decreased inhibition, or to an abnormal responsivity of the cortex due a decreased preactivation level remains disputed. Studies using transcranial magnetic stimulation in particular have yielded contradictory results. We will review here the available data on cortical excitability obtained with different methodological approaches in patients over the migraine cycle. We will show that these data congruently indicate that the sensory cortices of migraineurs react excessively to repetitive, but not to single, stimuli and that the controversy above hyper- versus hypo-excitability is merely a semantic misunderstanding. Describing the migrainous brain as 'hyperresponsive' would fit most of the available data. Deciphering the precise cellular and molecular underpinnings of this hyperresponsivity remains a challenge for future research. We propose, as a working hypothesis, that a thalamo-cortical dysrhythmia might be the culprit.

Asymmetric distribution of visual evoked potentials in patients with migraine with aura during the interictal phase

PURPOSE

One of the most commonly described electrocortical phenomena in patients with migraine is an increased interhemispheric asymmetry, in response to different sensory stimuli. This study aims to evaluate the bioelectrical activity of both occipital cortices in patients with migraine with visual aura (MA) during the interictal period, and its possible relationship with visual symptoms.

METHODS

The authors recorded visual evoked potentials (VEPs) simultaneously from the left (O1) and right (O2) occipital cortices (80% contrast 60', 30', 15', and 7.5' checkerboard stimuli reversed at 2 Hz) in 22 patients with MA and 20 control subjects. The main outcome measure was interhemispheric asymmetry (IA) for both implicit time and amplitude, defined as the difference between the left and right scalp derivation (in absolute values).

RESULTS

IA was significantly different in patients with MA with respect to controls when employing 60' (p<0.001) and 15' (p<0.05) checkerboard stimuli for implicit times, and 60' (p<0.05) checkerboard stimuli for amplitudes. On the other hand, IA was not statistically different (p>0.05) in patients with MA with respect to controls when employing 30' and 7.5' checkerboards for both implicit times and amplitudes, and 15' checkerboards for amplitudes. No correlations were found between IA and age, onset of disease, attack frequency, or side of headache/aura.

CONCLUSIONS

Patients with MA presented asymmetries in VEP responses not related to visual aura or to headache side during the pain-free phase. These abnormalities may be ascribed to abnormal visual information processing, resulting in a different cortical activation when both foveal and parafoveal stimuli are used.

The wolframin His611Arg polymorphism influences medication overuse headache

Homozygosis for wolframin (WFS1) mutations determines Wolfram syndrome (WS), and common polymorphisms of WFS1 are associated with psychiatric illnesses and dependence behaviour. To test the influence of WFS1 polymorphisms on medication overuse headache (MOH), a chronic headache condition related to symptomatic drugs overuse, we analyzed 82 MOH patients for the WFS1 His611Arg polymorphism, and performed a comparison between clinical features of Arg/Arg (R/R) and non-R/R individuals. Individuals harbouring the R/R genotype showed significantly higher monthly drug consumption (t=-3.504; p=0.00075) and more severe depressive symptoms on the BDI questionnaire (t=-3.048; p=0.003) than non-R/R. WFS1 polymorphism emerged as the only significant predictor of drug consumption, at the multivariate regression analysis (F=12.277; d.f.=1,80; p=0.00075, adjusted R2=0.122). These results implicate WFS1 in the clinical picture of MOH, may be through an influence on need for drugs as in other conditions of abuse behaviour.

Reduction of optic nerve fiber layer thickness in CADASIL

Our study aims to assess nerve fiber layer (NFL) thickness in patients affected by cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL). Six CADASIL patients (mean age 42 +/- 16 years, best corrected visual acuity >20/20 with refractive error between +/-3 diopters, intraocular pressure <18 mmHg) were enrolled. They were compared with 16 age-matched controls. In all subjects enrolled, NFL thickness was measured by optical coherence tomography (OCT). Three different measurements were taken in each quadrant (superior, inferior, nasal, and temporal) and averaged. The data from all quadrants (12 values averaged) were identified as NFL overall. In CADASIL eyes there was a reduction of NFL thickness in each quadrant and in the NFL overall evaluation compared with the values observed in control eyes. Our results suggest that in CADASIL patients there is a reduction of NFL thickness evaluated by OCT. This morphological abnormality could be ascribed to an impairment of the retinal vascular supply leading to a global neuroretinal involvement. These anatomical changes may precede the onset of the neurological clinical manifestations.

Early-onset progressive ataxia associated with the first CACNA1A mutation identified within the I–II loop

Familial hemiplegic migraine type 1, spinocerebellar ataxia type 6 (SCA6) and episodic ataxia type 2 (EA2) are allelic disorders associated with mutations in the CACNA1A gene, which encodes the alpha1 subunit of the P/Q-type calcium channel (Ca(V)2.1). SCA6 and EA2 share a number of clinical features, such as prominent cerebellar involvement and good response to acetazolamide therapy. However, while SCA6 develops as a late-onset, progressive ataxia, EA2 has an earlier, and episodic, onset. We report on two sisters with a heterogeneous clinical phenotype. The first developed progressive cerebellar ataxia after age 30, without noticeable episodes of vertigo or headache. A 1 year trial with acetazolamide did not produce significant results. The other reported episodes of vertigo, headache and gait imbalance since late childhood, with good response to acetazolamide, before developing moderate chronic cerebellar ataxia. Brain MRI showed cerebellar atrophy, especially in the vermis, in both patients. Direct sequencing of CACNA1A identified a heterozygous 1360G>A mutation in exon 11 resulting in the substitution of alanine for threonine at residue 454 (p.Ala454Thr). This is the first description of a change residing in the cytoplasmic I-II loop associated with a clinical phenotype.

A new POLG1 mutation with peo and severe axonal and demyelinating sensory-motor neuropathy

BACKGROUND

Progressive external ophthalmoplegia (PEO) is a mitochondrial disorder associated with defective enzymatic activities of oxidative phosphorylation (OXPHOS), depletion of mitochondrial DNA (mtDNA) and/or accumulation of mtDNA mutations and deletions. Recent positional cloning studies have linked the disease to four different chromosomal loci. Mutations in POLG1 are a frequent cause of this disorder.

METHODS

We describe two first-cousins: the propositus presented with PEO,mitochondrial myopathy and neuropathy, whereas his cousin showed a Charcot- Marie-Tooth phenotype. Neurophysiological studies, peroneal muscle and sural nerve biopsies, and molecular studies of mtDNA maintenance genes (ANT1, Twinkle, POLG1, TP) and non dominant CMT-related genes (GDAP1, LMNA, GJB1) were performed.

RESULTS

A severe axonal degeneration was found in both patients whereas hypomyelination was observed only in the patient with PEO whose muscle biopsy specimen also showed defective OXPHOS and multiple mtDNA deletions. While no pathogenetic mutations in GDAP1, LMNA, and GJB1 were found, we identified a novel homozygous POLG1 mutation (G763R) in the PEO patient. The mutation was heterozygous in his healthy relatives and in his affected cousin.

CONCLUSIONS

A homozygous POLG1 mutation might explain PEO with mitochondrial abnormalities in skeletal muscle in our propositus, and it might have aggravated his axonal and hypomyelinating sensory-motor neuropathy. Most likely, his cousin had an axonal polyneuropathy with CMT phenotype of still unknown etiology.

A novel ATP1A2 mutation in a family with FHM type II

Familial hemiplegic migraine (FHM) is a rare subtype of migraine with aura with an autosomal dominant pattern of inheritance. Six FHM families underwent extensive clinical and genetic investigation. The authors identified a novel ATP1A2 mutation (E700K) in three patients from one family. In the patients, attacks were triggered by several factors including minor head trauma. In one subject a 3-day coma developed after a cerebral angiography. Overall, the phenotype of the patients closely resembles that of previously reported cases of FHM type II. The E700K variant might be regarded as the cause of the disease in this family, but this was not tested functionally.

Ataxia with oculomotor apraxia type 2: A clinical, pathologic, and genetic study

BACKGROUND

Ataxia with oculomotor apraxia type 2 (AOA2) is characterized by onset between age 10 and 22 years, cerebellar atrophy, peripheral neuropathy, oculomotor apraxia (OMA), and elevated serum alpha-fetoprotein (AFP) levels. Recessive mutations in SETX have been described in AOA2 patients.

OBJECTIVE

To describe the clinical features of AOA2 and to identify the SETX mutations in 10 patients from four Italian families.

METHODS

The patients underwent clinical examination, routine laboratory tests, nerve conduction studies, sural nerve biopsy, and brain MRI. All were screened for SETX mutations.

RESULTS

All the patients had cerebellar features, including limb and truncal ataxia, and slurred speech. OMA was observed in two patients, extrapyramidal symptoms in two, and mental impairment in three. High serum AFP levels, motor and sensory axonal neuropathy, and marked cerebellar atrophy on MRI were detected in all the patients who underwent these examinations. Sural nerve biopsy revealed a severe depletion of large myelinated fibers in one patient, and both large and small myelinated fibers in another. Postmortem findings are also reported in one of the patients. Four different homozygous SETX mutations were found (a large-scale deletion, a missense change, a single-base deletion, and a splice-site mutation).

CONCLUSIONS

The clinical phenotype of oculomotor apraxia type 2 is fairly homogeneous, showing only subtle intrafamilial variability. OMA is an inconstant finding. The identification of new mutations expands the array of SETX variants, and the finding of a missense change outside the helicase domain suggests the existence of at least one more functional region in the N-terminus of senataxin.

Familial basilar migraine associated with a new mutation in the ATP1A2 gene

Basilar migraine (BM), familial hemiplegic migraine (FHM), and sporadic hemiplegic migraine (SHM) are phenotypically similar subtypes of migraine with aura, differentiated only by motor symptoms, which are absent in BM. Mutations in CACNA1A and ATP1A2 have been found in FHM. The authors detected a novel mutation in the ATP1A2 gene (R548H) in members of a family with BM, suggesting that BM and FHM may be allelic disorders.

Chronic axonal-demyelinating polyradicular neuropathy associated with mycosis fungoides: a case report

Case of a 58-year-old patient diagnosed as having mycosis fungoides (MF) who presented with sensory ataxia, limbs weakness and neurophysiological and laboratory signs indicative of autoimmune chronic mixed axonal-demyelinating sensory-motor polyradicular neuropathy. The possibility that MF may be associated with an immunomediated peripheral neuropathy, even in the absence of a direct invasion of the nerves and widespread visceral involvement, should be considered.

Quality of life in patients with Charcot-Marie-Tooth disease

The authors evaluated quality of life in Charcot-Marie-Tooth disease by administering the Medical Outcome Study Short Form-36 (SF-36) questionnaire to 121 Italian patients. Patients scored lower on all of the SF-36 scales compared with Italian normative data. Scores were lower in nonworking vs working patients, women vs men, and older vs younger patients, but not between patients with demyelinating vs axonal forms or between patients who had undergone orthopedic foot surgery vs those who had not.

Entrapment neuropathy in patients with spastic cerebral palsy

OBJECTIVES

We performed nerve conduction and needle electromyographic tests in 29 patients with spastic cerebral palsy (SCP) and severe limb deformities. Nerve conduction abnormalities were detected in 32 of 400 sensory or motor nerves, while 11 of 29 patients (37.9%) showed abnormal nerve conduction, indicating one or more entrapment neuropathies. Patients with SCP develop severe joint contractures and deformities due to spastic muscle tone and limited muscle and joint use/flexibility; these contractures and deformities can, in turn, cause nerve damage, possibly as a result of the stretching, angulation or compression mechanisms in the anatomic fibro-osseous passages, where nerves are particularly susceptible.

Abnormal head nociceptive withdrawal reaction to facial nociceptive stimuli in Parkinson's disease

INTRODUCTION

Trigemino-cervical-spinal reflexes (TCSRs) are complex brainstem stereotyped nociceptive responses involved in a defensive withdrawal reaction of the head from facial nociceptive stimuli.

OBJECTIVE

The present study was undertaken to collect data on possible TCSR abnormalities in idiopathic Parkinson's disease (PD) and investigate any correlation with motor signs and L-DOPA administration.

METHODS

TCSRs were registered from the semispinalis capitis and biceps brachii muscles after electrical stimulation of the supraorbital nerve in 18 patients with PD and 24 controls. The latency (L) and area (A), as well as the sensory (ST), painful (PT) and reflex (RT) thresholds were measured during the 'off' and 'on' state, and possible correlations with the UPDRS III total score, selected subscores (tremor, neck rigidity, upper limb rigidity, akinesia, rising from a chair, posture and posture instability) and duration of illness were investigated.

RESULTS

Significant changes between controls and PD patients were found in the L, A, PT and RT of TCSRs. These results were not significantly influenced by L-DOPA treatment. A significant correlation was found between neck rigidity, postural instability scores and duration of illness and the TCSR L and A values in PD patients in the 'off' state.

CONCLUSIONS

TCSRs abnormalities, combined with dopamine resistance, are consistent with a primary loss of brainstem neurons mediating a complex sensory-motor integration including neck muscle tone and postural control as well as the head withdrawal reaction to the nociceptive stimuli.

SIGNIFICANCE

TCSRs may represent a useful tool for the assessment of brainstem sensory-motor function in PD as well as other movement and degenerative disorders.

Novel SACS mutations in autosomal recessive spastic ataxia of Charlevoix-Saguenay type

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is an early-onset familial disease with prominent myelinated fibers in the optic fundus. ARSACS is frequent in the Charlevoix-Saguenay region of Quebec but rare elsewhere. Mutations in SACS, encoding sacsin, a protein of unknown function, are associated with ARSACS. The authors identified three new SACS mutations in two Italian patients whose phenotype closely matches that of Quebec cases, but without retinal striation.

Italian Huntington disease patients--data and tissue bank

We have collected clinical and genetic data on Huntington disease (HD) patients and their families over the last 5 years at the Unit of Neurogenetics, IRCCS Neuromed of Pozzilli (IS), Italy. Data on 854 mutation carriers are included in the data bank, together with a large number of DNA samples, blood, and other tissues. In particular, lymphoblastoid cell lines from 100 patients, including subjects carrying very rare genetic conditions (CAG mutation homozygosity, juvenile and infantile onset, pre-mutations) have been established. For all these initiatives ethical approval from the bioethics committee was obtained. We wish to extend this initiative to all families, investigators, and institutions within and, possibly outside, the Italian border in an attempt to enlarge the bank and to institute a HD Research Roster.

Cerebellar metabolite alterations detected in vivo by proton MR spectroscopy

The aim of our work was to evaluate the feasibility of in vivo single-voxel quantitative proton MR spectroscopy in order to identify possible alterations in the main metabolite concentrations due to some metabolic dysfunctions in the cerebellum of patients suffering from a particular form of migraine called "with aura." Measurements of metabolite levels in the cerebellum disclosed reduced choline values (normalized both to N-acetyl-aspartate and creatine) in the patient group with respect to the age-matched control group. Our interest in this pathology is motivated by the fact that there are no available specific biochemical markers for migraine characterization, and the current diagnostic only takes advantage of the medical history and the clinical examination.

Lack of habituation causes high intensity dependence of auditory evoked cortical potentials in migraine

Migraineurs are characterized interictally by lack of habituation, or even potentiation, of cortical evoked potentials during repetitive stimulation and by a strong intensity dependence of auditory evoked potentials (IDAP). To determine whether these two features of sensory processing are interrelated, we have studied them simultaneously on the same recordings of auditory evoked potentials (AEPs). AEPs were obtained at four different stimulation intensities in 14 patients suffering from migraine without aura (MO) and 14 healthy volunteers (HV). For each intensity, 120 trials were averaged off-line globally and over four sequential blocks of 30 trials. IDAP was expressed by the amplitude/stimulus intensity function (ASF slope) for global and block averages. Habituation was calculated as the percentage amplitude variation between the first and fourth blocks for each stimulus intensity. The IDAP slope for global averages was higher in MO (1.05 +/- 0.27 microV/10 dB) than in HV (0.64 +/- 0.45 microV/10 dB) (P = 0.008), but IDAP slopes for block averages were greater in MO only at the fourth block (P = 0.048). First block amplitudes tended to be lower in MO, except at 80 dB. There was a potentiation of AEP amplitudes at every stimulus intensity in MO, contrasting with habituation in HV. IDAP slopes were negatively correlated with mean habituation percentages in pooled data from patients and controls (r = -0.610; P = 0.0006). This study confirms that IDAP is higher in migraineurs than in healthy controls. It also shows that the AEP habituation is replaced by potentiation at all stimulus intensities. The negative correlation found between IDAP and habituation suggests that the latter is able to have a strong influence on the former and perhaps even lead to it. In migraine, the habituation deficit amplifies the IDAP and may thus be the causal functional abnormality. We propose that it is due to a decreased pre-activation level of sensory cortices, a hypothesis also supported in this study by the lower amplitude of first AEP blocks in patients.