Primary cervical dystonia and scoliosis: a multicenter case-control study

OBJECTIVE

To study the distribution of prior scoliosis among patients with primary adult-onset cervical dystonia (CD) and matched control subjects.

METHODS

Case and control subjects were selected among consecutive outpatients attending four Italian centers. Control outpatients were matched for age (+/-5 years), sex, and referral center. Information on prior scoliosis, other spine diseases, and family history of dystonia was obtained by a standardized questionnaire and supported by medical records. Conditional logistic regression models were used to adjust simultaneously for age, disease duration, and education level and to determine the independent association of exposure variables with the outcome.

RESULTS

Prior scoliosis developing in middle or late childhood or at around the puberty occurred more frequently among 72 case patients than among 144 neurologic control subjects. No subject reported conditions considered to be responsible for secondary scoliosis. The association of scoliosis and CD was not confounded by age, duration of disease, education level, other spine diseases, or family history of dystonia (adjusted odds ratio [OR] 6.8; 95% CI 1.5 to 29.5; p = 0.011). The OR of family history of dystonia (18.7; 95% CI 2.4 to 147.5; p = 0.005) fell to 11.7 (95% CI 1.3 to 103; p = 0.03) after controlling for scoliosis.

CONCLUSIONS

Prior scoliosis may increase the risk of developing CD. The observed decrease in the magnitude of the association between family history of dystonia and CD after controlling for scoliosis suggests a link between the two conditions.

Does sex influence age at onset in cranial-cervical and upper limb dystonia?

The relation between age at dystonia onset and sex was investigated in 264 patients with cranial-cervical dystonia and 56 patients with upper limb dystonia. In cranial-cervical dystonia, women had a significantly greater age at the onset of dystonia than men. The association was independent of duration of disease and distance of referral, but it was no longer detectable after adjustment for educational level. In upper limb dystonia, men and women did not differ for age at dystonia onset, duration of disease, education level, or distance of referral. A significant inverse association between age at the onset of dystonia and education was observed in both cranial-cervical dystonia and upper limb dystonia series.

Relaxation in distal and proximal arm muscles: a reaction time study

OBJECTIVE

To investigate whether the same mechanisms underlie muscle relaxation in proximal and distal arm muscles of normal subjects.

METHODS

Fourteen healthy subjects were studied using a simple visual reaction time paradigm. Relaxation reaction time (R-RT) and contraction reaction time (C-RT) were compared across different tasks involving distal (first dorsal interosseus, FDI, flexor carpi radialis, FCR) and proximal (biceps brachii, BB, triceps brachii, TR) arm muscles. Changes of FCR H-reflex before and during voluntary relaxation were investigated in two subjects.

RESULTS

No significant difference was observed between R-RT and C-RT in the distal muscles. The R-RT was significantly shorter than C-RT in both the BB and TR muscles. The relaxation latency (R-RT) was significantly correlated to the subjects' age in all the muscles except the FDI. No inhibition of the FCR H-reflex could be observed in the 20 ms preceding muscle relaxation.

CONCLUSIONS

Our findings suggest that neural mechanisms contribute differently to the relaxation of muscles with a different functional role. Voluntary relaxation in distal arm muscles is mainly related to the reduction of motor cortical output, while in proximal muscles a spinal disfacilitation is also present and possibly sustained by the modulation of presynaptic inhibition.

The medical management of spasticity

When spasticity produces a clinical disability by interfering with posture, motor capacity, nursing or daily living activities, medical treatment is recommended. It is mainly indicated when the muscle overactivity is diffusely distributed and should be implemented early, to prevent permanent musculoskeletal deformities or contractures. A pharmacological approach relies on the use of drugs which modulate neurotransmitters acting at the cortico-spinal level (GABA, glycine, glutamate, noradrenaline, serotonin). The aim of this treatment is to decrease spinal reflex excitability by reducing the release of excitatory neurotransmitters, or by potentiating the activity of inhibitory inputs. Evaluation of the efficacy of these drugs is determined by the therapeutic objectives which may be biomechanical, or functional. Diazepam increases presynaptic inhibition by stimulating GABA(A) receptors in the brainstem and spinal cord. In double-blind studies of patients with spinal cord lesions, antispastic efficacy has been shown, but side-effects are common. Baclofen stimulates GABA(B) receptors inducing a suppression of excitatory neurotransmitter release. Antispastic efficacy is sufficiently documented, but no definite effects on ambulation or activities of daily living have been proved. Tizanidine has an alpha2-agonist activity (at spinal and supraspinal level) and decreases the presynaptic activity of excitatory interneurones. The main clinical effects are a reduction in tonic stretch, polysynaptic reflexes, and co-contraction, with fewer side-effects but no definite functional change. The efficacy of several other antispastic drugs is documented in a few controlled studies, but the majority of information arises from open trials or anecdotal observations.

Differential modulation of motor evoked potential and silent period by activation of intracortical inhibitory circuits

OBJECTIVES

To investigate the effect of activation of intracortical inhibitory circuits, as tested by short interval (3 ms) paired-pulse transcranial magnetic stimulation (TMS) with a conditioning-test paradigm, on the electromyographic (EMG) pause (silent period, SP) following the motor evoked potential (MEP) in normal subjects.

METHODS

SPs and MEPs were recorded from the right first dorsal interosseous (FDI) muscle during a tonic voluntary contraction (from 70 to 90% of the maximum). Using a focal coil, we compared the SP duration after single-pulse TMS, paired-pulse TMS and single-pulse TMS of reduced intensity such as to evoke MEPs matched in size to the conditioned ones after paired-pulse TMS. In addition, we compared in a control experiment the duration of the SP following matched size MEPs evoked, respectively, by focal TMS with preferential activation of indirect I1- or I3-waves.

RESULTS

SP duration after paired-pulse TMS was significantly longer than after single-pulse TMS evoking MEPs of a similar size. In no case the SP duration was longer when focal TMS preferentially activated I1-waves.

CONCLUSIONS

The conditioning sub-threshold stimulus is more powerful in reducing the MEP size than in cutting down the subsequent EMG silence, suggesting that the neural circuits underlying MEP and SP are, at least in part, different.

No evidence of association between CAG expansions and essential tremor in a large cohort of Italian patients

Essential tremor (ET) is one of the most common movement disorders. However the pathogenesis is as yet unknown, although a genetic cause has long been recognised. Clinical and molecular evidences suggested that the ET gene might contain a CAG expanded region. In a cohort of Italian ET patients Repeat Expansion Detection (RED) approach did not demonstrate large CAG expansions. We extended the study towards specific targets: the channel proteins hSKCa3 and CACNL1A4. Direct assessment of CAG stretches within these two genes did not demonstrate any CAG expansion in affected subjects. Also a case-control analysis failed to reveal any evidence of association, thus excluding these genes as a cause of ET.

Tremor associated with benign IgM paraproteinaemic neuropathy successfully treated with gabapentin

We describe a 76-year-old patient with a severe tremor due to chronic demyelinating neuropathy associated with a benign IgM paraproteinaemia that was successfully treated with gabapentin. The patient reached the full dose of 1,200 mg/day of gabapentin without side effects and showed a significant therapy-related improvement of tremor and disability, as judged by the Fahn Tolosa Marin Rating Scale.

Abnormalities of sensorimotor integration in focal dystonia: a transcranial magnetic stimulation study

It has been postulated that sensorimotor integration is abnormal in dystonia. We investigated changes in motor cortical excitability induced by peripheral stimulation in patients with focal hand dystonia (12 patients with hand cramps) and with cervical dystonia (nine with spasmodic torticollis) compared with 16 age-matched normal controls. Motor evoked potentials (MEP) to focal (figure-of-eight coil) transcranial magnetic stimulation of the hand area were recorded from the right abductor pollicis brevis (APB), first dorsal interosseus (FDI), flexor carpi radialis and extensor carpi radialis muscles. Changes of test MEP size following conditioning stimulation of the right median nerve (or of the index finger) at conditioning-test (C-T) intervals of 50, 200, 600 and 1000 ms were analysed. Peripheral stimulation significantly reduced test MEP size in the APB and FDI muscles of normal control and spasmodic torticollis patients. The inhibitory effect was larger upon median nerve stimulation and reached a maximum at the C-T interval of 200 ms. On the contrary, hand cramp patients showed a significant facilitation of test MEP size. This study suggests that MEP suppression following peripheral stimulation is defective in patients with focal hand dystonia. Central processing of sensory input is abnormal in dystonia and may contribute to increased motor cortical excitability.

Clinical and genetic study of essential tremor in the Italian population

Essential tremor (ET) is one of the most common movement disorders. The pathogenesis is as yet unknown, although a genetic cause has long been recognised. Clinical and molecular evidence suggested that the ET gene contains a CAG expanded region. We examined a cohort of 240 Italian ET patients, classified as familial (193 cases) and sporadic (47 cases). The clinical manifestations of ET patients confirmed that the disorder is characterised by a large phenotypic variability. Repeat expansion detection (RED) approach did not demonstrate large CAG expansions. Six families were genotyped with 12 microsatellites markers of 2p and 3q regions and analysed according to parametrical methods. Lod scores values obtained in these families excluded the association of ET with 2p and 3q loci. Our findings confirm the presence of genetic heterogeneity and suggest that at least a third locus is involved in the pathogenesis of familial essential tremor.

Intracortical inhibitory circuits and sensory input: a study with transcranial magnetic stimulation in humans

We compared intracortical inhibition (ICI) following paired transcranial magnetic stimulation (TMS) (interstimulus interval, ISI: 3 ms) and the inhibition of motor evoked potentials (MEPs) to TMS induced by stimulation of the median nerve (ISI: 200 ms) in six normal subjects. MEPs evoked by focal TMS were recorded in the relaxed opponens pollicis muscle and the size of the conditioned responses was expressed as a percentage of the size of the non-conditioned responses. Maximal ICI, ranging from 4 to 40%, and inhibition after median nerve stimulation, ranging from 11 to 68%, were significantly correlated. The results suggest that both phenomena are possibly mediated by the same gamma aminobutyric acid-ergic (GABAergic) inhibitory circuits and that afferent inputs to the cortex may contribute to their physiological activation.

Abnormalities of motor cortical excitability are not correlated with clinical features in atypical parkinsonism

OBJECTIVE

To evaluate the specificity of motor cortical excitability changes in parkinsonian syndromes and their relevance to the pathophysiology of cardinal parkinsonian features.

METHODS

Paired transcranial magnetic stimulation (TMS) was used to assess cortico-cortical inhibition (CCI) and facilitation (CCF) in the opponens pollicis muscle of patients with atypical, non-L-dopa- (LD) responsive parkinsonism.

RESULTS

Compared with age-matched normal control subjects, CCI (interstimulus interval [ISI], 3 ms) was significantly reduced in 10 patients with predominantly parkinsonian multiple system atrophy (MSA-P) and in seven with vascular parkinsonism (VP), but not in four with predominantly cerebellar MSA. No significant change of CCF (ISI, 12 ms) was observed. No correlation was found between the amount of CCI and clinical status as evaluated with the Unified Parkinson's Disease Rating Scale (UPDRS). In 10 patients (5 MSA-P, 5 VP), CCI was significantly increased by LD acute administration without concurrent clinical changes.

CONCLUSIONS

Abnormalities of CCI are not peculiar to idiopathic Parkinson's disease and seem unlikely to underlie any specific parkinsonian feature, but rather possibly reflect a nonspecific imbalance of inhibitory and facilitatory motor cortical circuits.

Motor recovery following stroke: a transcranial magnetic stimulation study

OBJECTIVES

To verify the usefulness of early recording of motor evoked potentials (MEPs) in predicting motor outcome after stroke and to investigate the neural mechanisms underlying functional recovery following stroke.

METHODS

We performed a comparative analysis of the behaviour of motor responses evoked by transcranial magnetic stimulation (TMS) of the ipsilateral and contralateral motor cortex in the affected and unaffected thenar muscles of 21 consecutive patients with acute stroke.

RESULTS

According to the behaviour of MEPs in the affected muscles, patients could be divided into 3 groups: (a) 10 subjects with absent responses to TMS of both the damaged and undamaged hemisphere, whose motor recovery was poor and related to the size of MEPs on the normal side; (b) 5 subjects with larger MEPs upon TMS of the ipsilateral (undamaged) than of the contralateral (damaged) cortex, whose good recovery possibly resulted from the emergence of ipsilateral pathways; (c) 6 subjects with larger MEPs in the affected than in the unaffected muscles, whose good recovery was possibly subserved by alternative circuits taking over cortical deafferentation.

CONCLUSIONS

Early MEP recording in acute stroke provides useful information on the clinical prognosis and the different mechanisms of motor recovery.

The role of sensory cues in the rehabilitation of parkinsonian patients: a comparison of two physical therapy protocols

We devised a single-blind study to assess the role of providing external sensory cues in the rehabilitation of patients with idiopathic Parkinson's disease (PD). Twenty stable, nondemented patients with PD entered a 6-week rehabilitation program and were randomly assigned to two balanced protocols which were differentiated by the use of external sensory cues ("non-cued" vs "cued"). Patients were evaluated by a neurologist, who was blind to group membership, with the Unified Parkinson's Disease Rating Scale (UPDRS) at baseline, end of treatment, and after 6 weeks. Patient groups were comparable for age, disease duration, and severity. A significant reduction of UPDRS scores (activities of daily living and motor sections) was present after the rehabilitation phase in both groups. However, at follow up, while this clinical improvement had largely faded in the "non-cued" group, mean UPDRS scores of the "cued" group were still significantly lower than baseline values. The incorporation of external sensory cues in the rehabilitation protocol can extend the short-term benefit of physical therapy in moderately disabled patients with PD, possibly as a result of the learning of new motor strategies. "Cued" physical therapy for PD should be targeted to compensate for the defective physiological mechanisms.

Full length alpha-synuclein is present in cerebrospinal fluid from Parkinson's disease and normal subjects

Several clues suggest that alpha-synuclein, a presynaptic protein, plays a central role in the pathogenesis of idiopathic Parkinson's disease (PD). To search a peripheral marker of PD, we analyzed presence and amount of alpha-synuclein in CSF from 12 PD patients and 10 neurologically normal subjects. The protein was extracted from CSF samples through immunoprecipitation and immunoblotting with different specific anti-alpha-synuclein antibodies. We identified a 19 kDa band that corresponds to monomeric alpha-synuclein, given its comigration with homologue human recombinant peptide as well as with the protein extracted from cerebral cortex of normal subjects. The amount of CSF 19 kDa alpha-synuclein did not significantly vary in PD and normal cases. These findings have two implications: (a) full length alpha-synuclein is released by neurons in the extracellular space; (b) alpha-synuclein does not appear a peripheral marker of PD pathology.

Primary hemifacial spasm and arterial hypertension: a multicenter case-control study

In a case-control study, the authors found that arterial hypertension occurred more frequently among 115 patients with primary hemifacial spasm than among 115 neurologic controls matched for age (+/-5 years), sex, and referral center. The association was not confounded by education level, smoking history, diabetes, or other diseases (adjusted OR 2.64; 95% CI 1.3 to 5.33, p = 0.007). Hypertension was significantly associated with the outcome in the left-sided group (OR 4.0; 95% CI 1.4 to 11.5), but data concerning patients with right-sided spasm were inconclusive (OR 1.05; 95% CI 0.36 to 3.1). In our sample, hypertension either preceded or followed the onset of hemifacial spasm.

Corticobasal degeneration shares a common genetic background with progressive supranuclear palsy

Corticobasal degeneration is a sporadic form of tauopathy, involving the cerebral cortex and extrapyramidal motor system. A series of affected subjects was genotyped for a set of genetic markers along the tau protein gene. A specific haplotype is significantly overrepresented in patients versus controls. This haplotype is the same already reported in association with progressive supranuclear palsy. These data show that corticobasal degeneration and progressive supranuclear palsy, in addition to several clinical, pathological, and molecular features, may have the same genetic background.

Risk factors for spread of primary adult onset blepharospasm: a multicentre investigation of the Italian movement disorders study group

OBJECTIVES

Little is known about factors influencing the spread of blepharospasm to other body parts. An investigation was carried out to deterrmine whether demographic features (sex, age at blepharospasm onset), putative risk, or protective factors for blepharospasm (family history of dystonia or tremor, previous head or face trauma with loss of consciousness, ocular diseases, and cigarette smoking), age related diseases (diabetes, hypertension), edentulousness, and neck or trunk trauma preceding the onset of blepharospasm could distinguish patients with blepharospasm who had spread of dystonia from those who did not.

METHODS

159 outpatients presenting initially with blepharospasm were selected in 16 Italian Institutions. There were 104 patients with focal blepharospasm (mean duration of disease 5.3 (SD 1.9) years) and 55 patients in whom segmental or multifocal dystonia developed (mainly in the cranial cervical area) 1.5 (1.2) years after the onset of blepharospasm. Information was obtained from a standardised questionnaire administered by medical interviewers. A Cox regression model was used to examine the relation between the investigated variables and spread.

RESULTS

Previous head or face trauma with loss of consciousness, age at the onset of blepharospasm, and female sex were independently associated with an increased risk of spread. A significant association was not found between spread of dystonia and previous ocular diseases, hypertension, diabetes, neck or trunk trauma, edentulousness, cigarette smoking, and family history of dystonia or tremor. An unsatisfactory study power negatively influenced the validity and accuracy of the negative findings relative to diabetes, neck or trunk trauma, and cigarette smoking.

CONCLUSIONS

The results of this exploratory study confirm that patients presenting initially with blepharospasm are most likely to experience some spread of dystonia within a few years of the onset of blepharospasm and suggest that head or face trauma with loss of consciousness preceding the onset, age at onset, and female sex may be relevant to spread. The suggested association between edentulousness and cranial cervical dystonia may be apparent because of the confounding effect of both age at onset and head or face trauma with loss of consciousness. The lack of influence of family history of dystonia on spread is consistent with previous findings indicating that the inheritance pattern is the same for focal and segmental blepharospasm.

Intracortical inhibition after paired transcranial magnetic stimulation depends on the current flow direction

OBJECTIVES

To assess whether cortico-cortical inhibition (CCI) induced by paired-pulse transcranial magnetic stimulation (TMS) is influenced by 'preferential' or 'non-preferential' activation of the motor cortex.

METHODS

Paired-pulse TMS (conditioning-test paradigm with interstimulus intervals of 2-5 ms) with a round coil centered over the vertex was performed in 10 normal subjects using opposite current flow directions. The amount of CCI in the opponens pollicis and first dorsal interosseus muscles was determined.

RESULTS

When a clockwise current was induced in the brain (side A of the coil uppermost) a 'preferential' activation of the left hemisphere (right hand muscles) was observed, but the suppression of the test response by the conditioning stimulus (i.e. the CCI) was significantly greater in the left hand muscles. The situation was reversed when an anticlockwise current (side B of the coil uppermost) was induced in the brain. These effects occurred independently of the interstimulus interval, or of the absolute conditioning stimulus strength.

CONCLUSIONS

CCI is more effective in the 'non-preferentially' stimulated hemisphere, and the neural elements generating the indirect I3 wave are more sensitive to intracortical inhibition than those generating the I1 wave.

Changes of intracortical inhibition during motor imagery in human subjects

Paired-pulse transcranial magnetic stimulation with a conditioning-test paradigm was used to assess changes of corticocortical inhibition and facilitation during mental simulation of sequential finger movements in normal subjects. The cortico-cortical inhibition (at interstimulus interval, ISI, of 3 ms) was significantly reduced in the relaxed opponens pollicis (OP) muscle during motor imagery, regardless of the absolute size of the test motor evoked potential. The amount of cortico-cortical inhibition was similar to that observed during a mild voluntary contraction of the OP. No change of cortico-cortical facilitation was observed at the ISI of 12 ms. The data support the hypothesis that similar neural structures, including the primary motor cortex, are activated during both mental simulation and actual execution of motor activities.

Comparison of intracortical inhibition and facilitation in distal and proximal arm muscles in humans

1. Cortico-cortical inhibition and facilitation induced by paired transcranial magnetic stimulation (TMS) of the human motor cortex were investigated in the distal muscle opponens pollicis (OP) and the proximal muscle biceps brachii (BB) of normal subjects. 2. The test response evoked by TMS (125 % of motor threshold, MTh) in the relaxed OP and BB muscles was inhibited by a conditioning TMS (80 % of MTh) at short interstimulus intervals (ISIs; 2-5 ms) and facilitated at longer ISIs (10-25 ms). The test response was significantly less inhibited at short ISIs and more facilitated at long ISIs in the BB than OP. 3. The MTh at rest was significantly lower for the OP than for the BB, indicating a greater excitability of OP cortical area. However, the above pattern of inhibition and facilitation was preserved both when the stimulus intensity was adjusted to evoke test responses of matched size in the two muscles and within an ample range of conditioning stimulus intensities. 4. The use of a circular coil or a focal figure-of-eight coil produced no qualitative differences in the pattern of inhibition and facilitation in either muscle. 5. The significant difference in MTh between muscles was lost during voluntary activation. In both muscles, pre-innervation abolished the cortico-cortical facilitation and reduced the cortico-cortical inhibition. However, the latter remained larger in the OP than BB muscle. 6. We suggest that the different potency of intracortical inhibitory and facilitatory circuits directed towards distal and proximal arm muscles is related to their diverse prevalent functions.

Responses of masseter muscles to transcranial magnetic stimulation in patients with amyotrophic lateral sclerosis

We recorded motor responses evoked by transcranial magnetic stimulation (TMS) in the masseter muscles of 30 patients with amyotrophic lateral sclerosis (ALS), 10 patients with cervical spondylotic myelopathy (CSM) and 22 age-matched normal controls. Responses to direct activation of the trigeminal motor root (R-MEPs) were normal both in ALS and CSM patients. Responses to activation of cortico-bulbar descending fibers (C-MEPs) were absent or delayed in 19 ALS patients (63.3%). Abnormalities of masseter C-MEPs were more frequent than abnormalities of limb MEPs and could be observed both in patients with (77.8%) and without (41.7%) clinical bulbar signs. Masseter C-MEPs were normal in all CSM patients. Recording masseter responses to TMS can reveal the frequent impairment of cortico-bulbar projections in ALS and can be useful in the differential diagnosis of spinal cord compression disorders mimicking ALS because of combination of upper and lower motor neuron signs.

Predictive testing for Huntington's disease: ten years' experience in two Italian centres

Pre-symptomatic testing for Huntington's disease (HD) has been available as a clinical service in the medical centres of Rome and Genoa since December 1987, initially by DNA-linkage and since mid-1993 by direct mutation analysis. A multidisciplinary approach and a protocol which follows the Ethical Issue Policy Statement on Huntington's Disease Molecular Genetics Predictive Test has been used. In the period under study, 332 subjects requested the test, 288 were enrolled in the protocol and nearly half of these completed it. One hundred and forty-eight people withdrew from the testing procedure for various reasons but most frequently due to a more realistic evaluation of all possible consequences of test results, induced by psychological counselling. Therefore, 140 people completed the test. The overall gene-carrier/non-carrier ratio was 0.46:1. None of the identified gene carriers had catastrophic reactions such as suicide, suicide attempts or major psychiatric disorders. All appear to have had a similar pattern of reactions to an adverse result and none expressed regret for undergoing the test. In conclusion, presymptomatic testing for HD can be considered a safe procedure without adverse consequences when framed in an integrated protocol at qualified genetic centres.