Reciprocal inhibition in forearm muscles in patients with essential tremor

Reciprocal inhibition of the H-reflex in the forearm flexor muscles was studied in 11 patients with essential tremor and in 10 normal controls. Whereas patients and controls had a similar first, disynaptic phase of reciprocal inhibition, patients had a significantly reduced second phase. Patients with more severe functional impairment had more pronounced abnormalities of reciprocal inhibition. Abnormalities of reciprocal inhibition may play a role in the pathophysiology of essential tremor and probably arise from defective suprasegmental control. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:796–799, 1998.     

Reciprocal inhibition between the forearm muscles in patients with paroxysmal kinesigenic dyskinesia.

We measured the changes of forearm flexor H reflexes produced by conditioning radial nerve stimulation at delays of -2, 0, 2, 4, 7.5, 10, 25 and 75 ms in 10 patients with PKD and six with generalized seizure disorder. We compared the results with 12 normal volunteers. In the patients with PKD, we compared the amounts of reciprocal inhibition between the severely and the asymptomatic or mildly affected sides of arms. Follow-up studies were done in eight PKD patients after they responded to the anticonvulsant treatment. At each delay, patients with seizure disorders showed comparable amounts of changes with controls. Patients with PKD showed paradoxical facilitation at a delay of 0 ms, enhanced facilitation between 2 to 7.5 ms delays and attenuated inhibition at a delay of 75 ms. There were no significant differences in the amount of reciprocal inhibition according to the severity of clinical symptoms. Follow-up studies showed no significant changes of reciprocal inhibition compared to the baseline data. In PKD, paradoxical facilitation and enhanced first relative facilitation period may be caused by defective spinal interneurons. In addition to the defective reciprocal inhibition, abnormalities of supraspinal inputs seem to be involved in the genesis of PKD.     

Remission in spasmodic torticollis.

In 26 patients with spasmodic torticollis followed up for a median period of 12 years, the frequency of sustained remission was 23%, the median duration of remission was 8 years and duration of torticollis before remission 3 years. These results are more favourable than stated in the literature and should be taken into consideration before recommending surgical treatment.     

Botulinum toxin in spasmodic torticollis.

Ten patients with spasmodic torticollis were treated by injection of a total dose of 30 ng of botulinum toxin type A into the affected sternomastoid and posterior cervical muscles. Nine patients reported improvement in head position and control, which was confirmed in seven cases by clinical assessment and "blind" videotape ratings before and 6 weeks after injection. Five patients who had pain reported relief. Seven patients had mild transient dysphagia after injection; two who were given a more concentrated solution of the toxin developed more severe dysphagia, but this also recovered. Other minor transient side effects included weakness of the voice and local pain. The beneficial effects of botulinum toxin injections lasted some 2 to 3 months. A slight reduction in the total dose of toxin injected avoided the main side effects, and this method of treatment appears to offer successful control of head position and pain in the majority of patients with torticollis.     

Vestibular involvement in spasmodic torticollis.

Vestibular findings in a group of 35 patients with spasmodic torticollis without other otological or neurological symptoms were reviewed. The most consistent abnormality, present in more than 70% of cases, was a directional preponderance of vestibular nystagmus in the dark in a direction opposite to the head (chin) deviation. Rigidly clamping the head to a rotating chair did not abolish the directional preponderance. In the presence of optic fixation the directional preponderance was less frequent and its severity tended to diminish as a function of the duration of the disease. Smooth pursuit and optokinetic nystagmus were only occasionally affected. The results are indicative of primary involvement of the vestibular system in spasmodic torticollis and are discussed in terms of a break-down of the central mechanisms conveying sensory information responsible for head and eye orientation.     

Saccadic function in spasmodic torticollis.

Twelve patients with idiopathic spasmodic torticollis were compared with 19 normal controls on tests of saccadic eye movements thought to depend upon normal basal ganglia function. The patients were able to make random, predictive, remembered, and self-paced saccades equally as well as control subjects. This suggests that those parts of the basal ganglia which may be damaged in spasmodic torticollis, are separate from pathways responsible for the normal initiation and execution of saccades.     

Short latency trigemino-sternocleidomastoid response in muscles in patients with spasmodic torticollis and blepharospasm.

OBJECTIVES: To further elucidate the pathogenesis of focal dystonias. METHODS: Short latency responses can be recorded in tonically active sternocleidomastoid muscles after stimulation of the infraorbital branch of the trigeminal nerve. Such trigemino-sternocleidomastoid response consists of a bilateral positive/negative wave in the average of unrectified surface EMG, corresponding to a short period of inhibition of motor unit firing. This brain stem reflex was investigated in 10 normal subjects, in 16 patients affected by spasmodic torticollis (ST) and in 10 patients with blepharospasm (BSP). RESULTS: All ST patients presented abnormalities of SCM responses after infraorbital nerve stimulation. The abnormalities were bilateral in all but one of the patients and were independent from previous treatment with botulinum toxin. No BSP patients showed alterations of this reflex. CONCLUSIONS: Abnormalities of brain stem interneurons which are responsible for oligosynaptic exteroceptive suppression reflexes occur specifically in ST. These findings further support the relevance of sensory inputs in the determinism of focal dystonias.     

Selective denervation of neck muscles in the treatment of spasmodic torticollis. Preliminary results]

The authors present a review of the methods of surgical treatment of spasmodic torticollis, particularly the selective denervation of cervical muscles. Based on the literature and own experience cases treated by means of this method are described. Using selective ramisectomy it is possible to attain permanent improvement in most patients suffering from spasmodic torticollis, with very low complication rate. Our preliminary cases indicates that this method of treatment allows to acquire improvement of quality of life in patients with this particular type of dystonia.     

Botulinum toxin treatment in spasmodic torticollis.

Botulinum toxin A was administered to 19 patients in a double-blind placebo controlled trial. Toxin was more effective than placebo for improving both head position and pain which was measured by an objective rating scale and videofilm assessments. Following the controlled trial, treatment with botulinum toxin was continued in an open fashion. A total of 60 patients with torticollis received toxin in a total of 117 treatment periods. The mean follow up period was 8.4 months. In 39 patients with pain there was benefit in 77% of treatment periods. Some improvement in neck posture occurred in 83% of the treatment periods with a mean duration of 12 weeks. Side effects were frequent with dysphagia being the most common (28% of treatment periods). Botulinum toxin is an effective treatment for toticollis but treatment should be initiated with doses at the lower end of the range used in this study (400-600 mouse units).     

Social phobia in spasmodic torticollis

OBJECTIVES: To study the prevalence of psychiatric comorbidity assessed by the use of a structured clinical interview in a large, representative sample of patients with spasmodic torticollis (ST) and to test the hypothesis that social phobia would be highly prevalent. METHODS: In a consecutive cohort of 116 patients with ST treated with botulinum toxin overall psychiatric comorbidity was studied prospectively with the structured clinical interview (SCID) for DSM-IV axis I disorders. Physical disability and psychosocial variables were also assessed with standardised self rating questionnaires. RESULTS: 41.3% of the subjects met DSM-IV clinical criteria A-G for current social phobia as the primary psychiatric diagnosis. This figure rose to 56% including secondary and tertiary psychiatric diagnosis. There was no correlation between severity of disease (Tsui score, severity of pain, body image dissatisfaction score) and psychiatric comorbidity. The only significant predictor of psychiatric comorbidity was depressive coping behaviour (logistic regression analysis, p < 0.01; OR=10.8). Compared with a representative sample of the general adult population, in the patients with ST the prevalence of clinically relevant social phobia is 10-fold, of mood disorders 2.4-fold, and of lifetime psychiatric comorbidity 2.6-fold increased. CONCLUSIONS: A particularly high prevalence of social phobia was found in the cohort of patients with ST. The finding of a high prevalence of social phobia and depressive coping behaviour as the main predictor of psychiatric comorbidity may make a subgroup of patients with ST particularly amenable to specific psychotherapeutic interventions.     

Brain involvement in spasmodic torticollis

Cortical atrophy of unknown cause was revealed by pneumoencephalography in 10 of the 13 patients with spasmodic torticollis (77 %). There was no predominantly hysteric structure of personality. The results support an organic aetiology of spasmodic torticollis and suggest that the lesion is localized in the frontoparietal cortical areas of the brain.     

Cervico-ocular function in patients with spasmodic torticollis.

The cervico-ocular (COR) and active and passive vestibulo-ocular reflexes (VOR) were measured in seven patients with spasmodic torticollis (ST) and six normal controls. The COR was found to be weak or absent in both groups. The VOR gain was similar in the two groups but five patients had a significant asymmetry of the response. There was no evidence of abnormal cervico-vestibular interaction during active head rotation. The study suggests that the VOR asymmetry frequently found in ST cannot be explained on the basis of an abnormal cervical input.     

Cerebrospinal fluid protein patterns in spasmodic torticollis.

In order to investigate the value of CSF-protein analyses in spasmodic torticollis CSF from six patients with probable organic and two patients with probable psychogenic torticollis was examined by isoelectric focusing and electrophoresis. In all the patients with organic torticollis two pathological CSF-protein fractions were found in the alkaline region on electrofocusing and in four cases aberrant fractions occurred also in the acidic pH range. An increasing number of abnormal fractions were noted during at least the first year after onset of symptoms. Lithium treatment of three patients resulted in a striking decrease of torticollis as well as of the number of abnormal CSF-protein fractions. During placebo treatment of two cases, torticollis and the pathological CSF-proteins recurred. Some observations, including a few previous autopsy findings, might indicate that an encephalitogenic agent is involved in the pathogenesis of organic torticollis. In the patients with psychogenic torticollis the CSF-protein pattern was normal. This investigation supports a recent suggestion that organic and psychogenic torticollis might be distinguished by electrofocusing of the CSF-protein.     

Spontaneous remissions in spasmodic torticollis

We reviewed the frequency of spontaneous remissions in spasmodic torticollis (ST). One hundred sixteen patients with idiopathic ST (72 F, 44 M) were examined. The age at onset ranged from 9 to 69 (mean, 38.1 +/- 1.3). Twenty-one patients (18%) were Jewish. Eleven patients (9%) had a history of familial dystonia. Remissions longer than 1 year unrelated to treatment were observed in 14 patients (12%) (9 F, 5 M). They occurred in the first year of ST in 13 patients (93%) and in the eighth year in 1. Duration of remissions ranged from 1 to 20 years (mean, 6.5 +/- 1.6). Two patients had three remissions, and another had two. The mean age at the onset of ST in patients with remission was 26.4 +/- 3.3 (SEM) and ranged from 9 to 49. The age at the onset in the patients without remissions was 39.7 +/- 1.4, ranging from 10 to 69 (p less than 0.01). In the remission group, 3 patients were Jewish (21%); in the non-remission group, 18 (18%) were Jewish. There was a familial history in 1 case with remission (7%) and in 10 cases (10%) without remission. Spontaneous remissions in the course of ST seem to be more frequent in patients with early onset, and they occur usually during the first year.     

Comparative radiological study between spasmodic torticollis and Parkinson's disease. Notes on the etiology of spasmodic torticollis]

The comparative clinic-radiological study between 45 patients with spasmodic torticollis and the same amount of patients with either essential Parkinsonism or tremor is reported. The study was based mainly on the alterations verified by plain roentgenograms and pneumoencephalography. The comparison between the findings obtained on both groups led the authors to conclude that neuroradiological aspects have statiscally no value in clarifying the etiology of the spasmodic torticollis.     

Ocular counterrolling abnormalities in spasmodic torticollis

Spasmodic torticollis is a focal dystonic movement disorder of unknown origin, long hypothesized to have some vestibular involvement. An examination of otolith function, ocular counterrolling, was performed on eight patients with this disorder. The test consisted of photographing both eyes while the subject underwent rotation in both naso-occipital and earth-horizontal long axes. Measurements of eye torsion were made with a superimposition technique accurate to 0.1 degrees. Results showed all eight patients had abnormal ocular counterrolling. The most notable defect was the lack of sustained eye torsion at the extreme positions, resulting in rolling of the eyes in the direction of head tilt rather than counterrolling, a phenomenon previously observed only in persons with known brain-stem problems. That finding, as well as the majority of the patients showing spontaneous vestibular nystagmus in the dark and directional preponderance with caloric stimulation, implies that one difficulty in spasmodic torticollis lies in central vestibular connections, manifested by disruption of brain-stem pathways.     

Brain-stem auditory-evoked potentials in spasmodic torticollis

The pathophysiology of idiopathic spasmodic torticollis is uncertain. Cerebral, basal ganglia, brain-stem, and cervicomedullary lesions have been implicated. Some investigators have found evoked-potential abnormalities, while others have not. We recorded brain-stem auditory-evoked potentials in six patients with otherwise normal result of examinations and laboratory studies. Brain-stem auditory-evoked potentials were recorded from Cz-A1 and Cz-A2 with rarefaction clicks delivered at 11.1/s and 70 dB above sensory threshold with 40-dB contralateral masking. Analysis time was 10 ms, filter bandpass was 150 to 3000 Hz, and 4000 averages were replicated. Patients and age-matched controls were compared by Student's t test. One patient had I-III and I-V interpeak latencies (IPLs) beyond clinical norms (99% tolerance limit). Mean IPLs ipsilateral to torticollis were 2.32 +/- 0.2 (I-III), 1.96 +/- 0.4 (III-V), and 4.16 +/- 0.3 (I-V). Contralateral IPLs were 2.0 +/- 0.2 (I-III), 2.0 +/- 0.2 (III-V), and 3.9 +/- 0.5 (I-V). Control values were 2.04 +/- 0.2 (I-III), 1.86 +/- 0.2 (III-V), and 3.86 +/- 0.4 (I-V). Absolute latencies, V/I amplitude ratios, and III-V IPLs did not differ significantly between patients and controls, nor did IPLs contralateral to torticollis. Ipsilateral I-III and I-V IPLs were greater in patients than in controls. These findings are consistent with those of some clinical reports and with experimental evidence that brain-stem lesions produce torticollis. They imply brain-stem dysfunction ipsilateral to head deviation in at least some patients with torticollis.     

Vestibular hyperreactivity in patients with idiopathic spasmodic torticollis.

Ocular motor tests performed on 14 patients with idiopathic spasmodic torticollis were normal. The vestibulo-ocular reflex tested in eight patients showed a significant high level in seven. It is suggested that this phenomenon is secondary rather than the cause of spasmodic torticollis.