Myoclonus and other jerky movement disorders

Myoclonus and other jerky movements form a large heterogeneous group of disorders. Clinical neurophysiology studies can have an important contribution to support diagnosis but also to gain insight in the pathophysiology of different kind of jerks. This review focuses on myoclonus, tics, startle disorders, restless legs syndrome, and periodic leg movements during sleep. Myoclonus is defined as brief, shock-like movements, and subtypes can be classified based the anatomical origin. Both the clinical phenotype and the neurophysiological tests support this classification: cortical, cortical-subcortical, subcortical/non-segmental, segmental, peripheral, and functional jerks. The most important techniques used are polymyography and the combination of electromyography-electroencephalography focused on jerk-locked back-averaging, cortico-muscular coherence, and the Bereitschaftspotential. Clinically, the differential diagnosis of myoclonus includes tics, and this diagnosis is mainly based on the history with premonitory urges and the ability to suppress the tic. Electrophysiological tests are mainly applied in a research setting and include the Bereitschaftspotential, local field potentials, transcranial magnetic stimulation, and pre-pulse inhibition. Jerks due to a startling stimulus form the group of startle syndromes. This group includes disorders with an exaggerated startle reflex, such as hyperekplexia and stiff person syndrome, but also neuropsychiatric and stimulus-induced disorders. For these disorders polymyography combined with a startling stimulus can be useful to determine the pattern of muscle activation and thus the diagnosis. Assessment of symptoms in restless legs syndrome and periodic leg movements during sleep can be performed with different validated scoring criteria with the help of electromyography.

Increased whole-body auditory startle reflex and autonomic reactivity in children with anxiety disorders

BACKGROUND

Young patients with anxiety disorders are thought to have a hypersensitive fear system, including alterations of the early sensorimotor processing of threatening information. However, there is equivocal support in auditory blink response studies for an enlarged auditory startle reflex (ASR) in such patients. We sought to investigate the ASR measured over multiple muscles (whole-body) in children and adolescents with anxiety disorders.

METHODS

Between August and December 2006, we assessed ASRs (elicited by 8 consecutive tones of 104 dB, interstimulus interval of about 2 min) in 25 patients and 25 matched controls using a case-control design and in 9 nonaffected siblings. We recorded the electromyographic activity of 6 muscles and the sympathetic skin response. We investigated response occurrence (probability %) and response magnitude (area under the curve in microV x ms) of the combined response of 6 muscles and of the single blink response.

RESULTS

In patients (17 girls, mean age 12 years; 13 social phobia, 9 generalized anxiety, 3 other), the combined response probability (p = 0.027) of all muscles, the combined area under the curve of all muscles (p = 0.011) and the sympathetic skin response (p = 0.006) were enlarged compared with matched controls. The response probability (p = 0.48) and area under the curve (p = 0.07) of the blink response were normal in patients compared with controls. The ASR pattern was normal with normal latencies in patients compared with controls. In nonaffected siblings, the sympathetic skin response (p = 0.038), but not the combined response probability of all muscles (p = 0.15), was enlarged compared with controls.

LIMITATIONS

Limitations are the sample size and restricted comparison to the psychophysiological ASR paradigm.

CONCLUSION

The results point toward a hypersensitive central nervous system (fear system), including early sensorimotor processing alterations and autonomic hyperreactivity. The multiple muscle (whole-body) ASR is suggested to be a better tool to detect ASR abnormalities in patients with anxiety disorders than the blink response alone. Abnormalities in ASR serve as a candidate endophenotype of anxiety disorders.

Prediction of poor outcome in anoxic-ischemic coma

Most patients who are comatose a few hours after a period of global cerebral ischemia have a poor prognosis. In a series of studies selected with strict criteria for study design, the median prevalence of death or survival in a vegetative state was 78% (range, 56-90%) (Zandbergen et al., 1998). Most nonsurvivors die within the first weeks, not from brain damage, but from cardiac or pulmonary complications. Uncertainty about treatment and nontreatment decisions is therefore most critical during this period. To reduce this uncertainty among caregivers, and the related anxiety among family members, early identification of patients with such a poor prognosis is desirable.

Neuropsychological and clinical correlates of antisaccade task performance in schizophrenia

OBJECTIVES

To elucidate pathophysiologic mechanisms involved in abnormal antisaccade task performance in schizophrenia by investigating a possible relationship among antisaccade task performance, neuropsychological test results, and symptomatology in a group of young patients with recent-onset schizophrenia; to compare the effects of olanzapine and risperidone on antisaccades and reflexive saccades.

BACKGROUND

Patients with schizophrenia consistently perform worse than controls on the antisaccade task in which the subject is required to inhibit a reflexive saccade to a suddenly appearing visual target and look in the opposite direction.

METHODS

In 37 young (mean age 21 years), medicated patients with recent-onset schizophrenia the authors assessed antisaccades, reflexive saccades, neuropsychological test performance, and symptomatology. A subgroup of 18 patients was treated with olanzapine, and 15 patients were treated with risperidone. Reflexive-saccade and antisaccade task results were compared with those obtained in 13 control subjects.

RESULTS

The antisaccade error rate was significantly higher in the patients than in the control subjects. In the patients, poor working memory function was related to increased antisaccade error rate. Severity of disorganization symptoms at intake was related to prolonged mean latency of the correct antisaccades. Patients on risperidone had a prolonged mean latency in the reflexive saccade task compared with patients using olanzapine.

CONCLUSIONS

Abnormal antisaccade task performance is already present in early schizophrenia and may reflect working memory dysfunction. In future studies, medication effects should be considered in interpreting eye movement test results of patients with schizophrenia.

Soleus H-reflex tests in causalgia-dystonia compared with dystonia and mimicked dystonic posture

Dystonia in the causalgia-dystonia syndrome is characterized by a fixed dystonic posture. To identify involvement of central pathophysiologic mechanisms, we analyzed soleus H-reflex tests in five patients with causalgia-dystonia. Soleus H-reflex test results in these patients differed from those in healthy controls but were similar to those in purely dystonic patients and healthy controls mimicking dystonic posture. The results suggest involvement of supraspinal mechanisms in the abnormal posture of causalgia-dystonia.

Progression of abnormalities in adrenomyeloneuropathy and neurologically asymptomatic X-linked adrenoleukodystrophy despite treatment with "Lorenzo's oil"

OBJECTIVES

X-linked adrenoleukodystrophy (X-ALD) is an inherited disorder of peroxisomal fatty acid oxidation, biochemically characterised by the accumulation of saturated very long chain fatty acids (VLCFAs), particularly hexacosanoic acid (C26:0). Dietary treatment with a 4:1 mixture of glyceroltrioleate and glyceroltrierucate ("Lorenzo's oil") normalises plasma VLCFA concentrations, but neither ameliorates nor arrests the rapid progression of neurological symptoms in the cerebral variants of X-ALD. The efficacy of "Lorenzo's oil" in the milder phenotypes of X-ALD was assessed, as this has been much less investigated.

METHODS

Twenty two patients who were treated with "Lorenzo's oil" for at least 12 months for a median period of 2.5 (range 1.0-6.0) years were studied. Two had asymptomatic ALD, four the "Addison only" variant, 13 adrenomyeloneuropathy (AMN), and three were symptomatic female carriers.

RESULTS

The plasma C26:0 concentration normalised or near normalised in 19 patients (86%), in the three others it decreased significantly. Nevertheless, disability as measured with the extended disability status scale score increased mildly (0.5 (95% confidence interval (95% CI) 0.25-1.0)) in the 16 patients with neurological symptoms. Furthermore, one "Addison only" patient and one patient with AMN developed cerebral demyelination, and another "Addison only" patient developed AMN. Adrenocortical insufficiency evolved in one patient with AMN, and hypogonadism in one patient with asymptomatic ALD and two patients with AMN. Nerve conduction, evoked potential studies (SEP, BAEP, VEP), and abnormalities on cerebral MRI did not improve. On the other hand, side effects were often noted-namely, mild increases in liver enzymes (55%), thrombocytopenia (55%), gastrointestinal complaints (14%), and gingivitis (14%). We also found a mild decrease in haemoglobin concentration and leucocyte count.

CONCLUSIONS

The data suggest that treatment with "Lorenzo's oil" neither improved neurological or endocrine function nor arrested progression of the disease. Furthermore, the oil often induced adverse effects. Therefore, it is advocated that "Lorenzo's oil" should not be prescribed routinely to patients with X-ALD who already have neurological deficits.

A comparison of myogenic motor evoked responses to electrical and magnetic transcranial stimulation during nitrous oxide/opioid anesthesia

Transcranial motor evoked potentials (tc-MEPs) are used to monitor spinal cord integrity intraoperatively. We compared myogenic motor evoked responses with electrical and magnetic transcranial stimuli during nitrous oxide/opioid anesthesia. In 11 patients undergoing spinal surgery, anesthesia was induced with i.v. etomidate 0.3 mg/kg and sufentanil 1.5 microg/kg and was maintained with sufentanil 0.5 microg x kg(-1) x h(-1) and N2O 50% in oxygen. Muscle relaxation was kept at 25% of control with i.v. vecuronium. Electrical stimulation was accomplished with a transcranial stimulator set at maximal output (1200 V). Magnetic transcranial stimulation was accomplished with a transcranial stimulator set at maximal output (2 T). Just before skin incision, triplicate responses to single stimuli with both modes of cortical stimulation were randomly recorded from the tibialis anterior muscles. Amplitudes and latencies were compared using the Wilcoxon signed rank test. Bilateral tc-MEP responses were obtained in every patient with electrical stimulation. Magnetic stimulation evoked only unilateral responses in two patients. With electrical stimulation, the median tc-MEP amplitude was 401 microV (range 145-1145 microV), and latency was 32.8 +/- 2.3 ms. With magnetic stimulation, the tc-MEP amplitude was 287 microV (range 64-506 microV) (P < 0.05), and the latency was 34.7 +/- 2.1 ms (P < 0.05). We conclude that myogenic responses to magnetic transcranial stimulation are more sensitive to anesthetic-induced motoneural depression compared with those elicited by electrical transcranial stimulation.

IMPLICATIONS

Transcranial motor evoked potentials are used to monitor spinal cord integrity intraoperatively. We compared the relative efficacy of electrical and magnetic transcranial stimuli in anesthetized patients. It seems that myogenic responses to magnetic transcranial stimulation are more sensitive to anesthetic-induced motoneural depression compared with electrical transcranial stimulation.

Systematic review of early prediction of poor outcome in anoxic-ischaemic coma

BACKGROUND

Studies to assess the prognostic value of early neurological and neurophysiological findings in patients with anoxic-ischaemic coma have not led to precise, generally accepted, prognostic rules. We did a systematic review of the relevant literature to assess whether such rules could be derived from the combined results of these studies.

METHODS

From Medline and Embase databases we selected studies concerning patients older than 10 years with anoxic-ischaemic coma in which findings from early neurological examination, electroencephalogram (EEG), or somatosensory evoked potentials (SSEP) were related to poor outcome--defined as death or survival in a vegetative state. We selected variables with a specificity of 100% for poor outcome in all studies, and expressed the overall prognostic accuracy of these variables as pooled positive-likelihood ratios and as 95% CIs of the pooled false-positive test rates.

FINDINGS

In 33 studies, 14 prognostic variables were studied, three of which had a specificity of 100%: absence of pupillary light reflexes on day 3 (pooled positive-likelihood ratio 10.5 [95% CI 2.1-52.4]; 95% CI pooled false-positive test rate 0-11.9%); absent motor response to pain on day 3 (16.8 [3.4-84.1]; 0-6.7%); and bilateral absence of early cortical SSEP within the first week (12.0 [5.3-27.6]; 0-2.0%). EEG recordings with an isoelectric or burst-suppression pattern had a specificity of 100% in five of six relevant studies (pooled positive-likelihood ratio 9.0 [2.5-33.1]; 95%CI pooled false-positive test rate 0.2-5.9%). These characteristics were present in 19%, 31%, 33%, and 33% of pooled patient populations, respectively. For the 11 SSEP studies, results did not significantly differ between studies in which the treating physicians were or were not masked from the test result, prospective and retrospective studies, studies with short and long follow-up periods, and studies with high or low overall poor outcome.

INTERPRETATION

SSEP has the smallest CI of its pooled positive-likelihood ratio and its pooled false-positive test rate. Because evoked potentials are also the least susceptible to metabolic changes and drugs, recording of SSEP is the most useful method to predict poor outcome.

Electromyography in cervical dystonia: changes after botulinum and trihexyphenidyl

BACKGROUND

The value of physical examination in detecting involved neck muscles in cervical dystonia (CD) is uncertain and little is known about changes in electromyographic (EMG) features after botulinum toxin type A (BTA) treatment.

METHODS

In a double-blind, randomized study we recorded the EMG activities of 420 neck muscles in 42 patients with CD before and after treatment with BTA or trihexyphenidyl. We regarded any needle EMG activity higher than 100 microV as the gold standard for involuntary involvement of a muscle in the dystonic posture and compared this with the results of physical examination. We calculated EMG total scores by adding the scores of the individual muscles.

RESULTS

Physical examination had a low predictive value in the detection of involved muscles. There was a significant correlation between changes in EMG total scores and changes in clinical measurements. We observed increased EMG activity in 20% of noninjected muscles after BTA treatment and in 27% of noninjected muscles after trihexyphenidyl treatment. A switch from one most active muscle to another was seen equally in both groups and had no influence on clinical response.

CONCLUSION

Physical examination alone is not sufficient to detect involved muscles, and repeated, simultaneous EMG-guided application of BTA may be helpful. In addition to clinical measurements, changes in EMG activity due to treatment can be used as a physiologic measure in evaluating treatment response. Increased activity of noninjected muscles and a switch from one most active muscle to another are not related to BTA treatment, but are probably pathophysiologic phenomena of CD itself.

Slowing on quantitative spectral EEG is a marker for rate of subsequent cognitive and functional decline in early Alzheimer disease

The relation between quantitative spectral electroencephalogram (qEEG) parameters and subsequent rate of cognitive, functional, and behavioral decline in 82 consecutive patients with early probable Alzheimer disease (NINCDS-ADRDA criteria) was examined in a prospective study. The qEEG was performed at initial examination and global cognitive function, activities of daily living, and behavior were assessed at initial evaluation and after a period of 6 months. Using multiple linear regression analysis, higher frontocentral and parieto-occipital theta values, lower parieto-occipital beta values, and lower peak frequency were significantly associated with more decline in global cognitive function over the follow-up period. In addition, lower parieto-occipital beta values were significantly related to more decline in activities of daily living. These associations were independent of demographic (age, sex, and education) and disease characteristics [initial Cambridge Examination for Mental Disorders of the Elderly Cognitive test (CAMCOG) or Mini-Mental State Examination scores, estimated duration of symptoms, estimated prior rate of decline, and dementia severity]. In a separate multiple logistic regression analysis, prediction of rapidly progressive decline, defined as 8 or more points decline in CAMCOG scores (n = 21), could be made with parieto-occipital and frontocentral beta values. The results suggest that slowing on qEEG is a marker for subsequent rate of cognitive and functional decline in mildly demented AD patients, independent of demographic or disease characteristics.

Predicting survival in patients with early Alzheimer's disease

We investigated whether an index based on clinical features, electroencephalogram and computed tomography is useful to predict survival in early Alzheimer's disease. One hundred and sixty-three consecutively referred patients to an outpatient memory clinic and first diagnosed with Alzheimer's disease (105 'probable' and 58 'possible', NINCDS-ADRDA criteria) were studied and outcome measure was death. Cox proportional hazards regression analysis and Kaplan-Meier survival curves were used to investigate relations between baseline parameters and survival. Eighty-four patients (51. 5%) died during the follow-up period that extended to 5.8 years, with a median duration of survival after entry of 4.3 years. Baseline factors that were statistically significant and independently related to increased risk of mortality were high age, male sex, poor cognitive function as measured with the CAMCOG, low alpha and beta power on electroencephalogram, and temporoparietal atrophy on computed tomography scan. These results were independent of the diagnosis probable or possible Alzheimer's disease. Based on the coefficients from the regression equation, we computed a survival index for each patient and we constructed three groups according to tertiles of this index. After 5.2 years of follow-up, survival curves showed a low mortality group with 81.7% patients alive (median survival at least 5.7 years), an intermediate mortality group with 35.9% patients alive (median survival 3.8 years), and a high mortality group with no patients alive (median survival 2.3 years). Log rank tests were statistically significant for comparisons between all three groups. We conclude that an overall index combining demographic, cognitive, electroencephalogram and computed tomography features is a strong predictor of survival in early Alzheimer's disease.

[Writer's cramp treated with botulinum injections]

OBJECTIVE

To evaluate the first clinical experience with local botulinum toxin A (BTA) injections in patients with writer's cramp.

DESIGN

Descriptive.

SETTING

Academic Medical Centre, Amsterdam, the Netherlands.

METHOD

In May 1993-January 1996 ten patients with writer's cramp were treated with BTA (Dysport). Age of the patients varied from 28 to 68 years, the duration of complaints from 1 to 29 years. Muscles for injections were selected by observation, sometimes combined with electromyography. BTA was administered under electromyographic guidance.

RESULTS

The amount of BTA administered per treatment session ranged from 15 to 400 IU. In three patients the BTA-induced weakness necessary to reach a beneficial effect on writing was unacceptable. In seven patients the response was satisfactory or good and lasted 2 to 15 months (mean: 3.5 months).

CONCLUSION

The results confirm the efficacy of BTA in writer's cramp.

The late blink reflex response abnormality due to lesion of the lateral tegmental field

We report on a blink reflex abnormality observed in two patients, which provides additional information on the central pathways mediating this reflex. Autopsy was performed in one patient and MRI in the other. In the first patient there was a small lesion at the dorsal middle third of the lateral tegmental field and in the second patient at the level of the dorsal lower third of the medulla oblongata. In both patients the common finding was the absence of the late response (R2) ipsilateral to the side of the lesion, while the R2 response on the unaffected side was normal regardless of the side of the supraorbital nerve stimulation. The R1 responses were normal. This type of blink reflex abnormality has not been reported before and is referred to by us as 'tegmental type' of R2 abnormality. The results led to the conclusions that: (i) the crossed and uncrossed ascending trigeminofacial connections are mediated through the lateral tegmental field; (ii) the uncrossed trigeminofacial connection originates at the level of at least the lower medulla oblongata; (iii) the contralateral R2 response is established by way of an ascending pathway, which crosses the midline at the level of at least the lower third of the medulla oblongata.

Unusual recovery from acute panautonomic neuropathy after immunoglobulin therapy

A 33-year-old woman with acute idiopathic postganglionic panautonomic neuropathy experienced prompt recovery of all dysautonomic symptoms after receiving high-dose intravenous immunoglobulin therapy. Her recovery was complete within 6 months after onset of disease. This unusually rapid and complete recovery in comparison with that of historical control subjects suggests that patients with acute, severe, and widespread autonomic failure might benefit from intravenous immunoglobulin therapy.

Peripheral nerve abnormalities in adrenomyeloneuropathy: a clinical and electrodiagnostic study

Adrenomyeloneuropathy (AMN) is one of the most frequent phenotypes of X-linked adrenoleukodystrophy. Whether the polyneuropathy in AMN results from primary demyelination or axonal degeneration is uncertain. We examined 23 patients (18 men with AMN and five female carrier with AMN symptomatology), performed electroneurography and EMG, and compared our results with standardized electrodiagnostic criteria for primary demyelination. Both clinically and electrodiagnostically, the lower extremities were most frequently and most severely affected. A longer duration of symptoms was related to more severe pyramidal dysfunction (p < 0.004) and spasticity (p < 0.04), and to a more severe impairment of vibration sense (p < 0.05). There were on correlations between the different electrophysiologic studies and the duration of neurologic symptoms. Only two AMN patients (9%) fulfilled the electrodiagnostic criteria for primary demyelination. However, both had abnormally low compound muscle action potentials, which may have been a reflection of primary axonal degeneration. Six other patients (26%) partially fulfilled the criteria for primary demyelination, of whom five also manifested low compound muscle action potentials. In 15 patients (65%), we found polyneuropathy with predominantly axonal, sensorimotor features. We conclude that the neuropathy in AMN patients is due to primary axonal degeneration.

Soleus H reflex extinction in controls and spastic patients: ordered occlusion or diffuse inhibition?

Extinction of the soleus H reflex at higher stimulus intensities is commonly attributed to retrograde conduction of action potentials in motor axons. This study was designed to gain further insight into the mechanisms underlying the extinction. The decrease of the H reflex was quantified in a group of controls and spastic patients, with and without depression of the H response by continuous tendon vibration. Response amplitudes were normalized as a percentage of the maximal M wave amplitude. Stimuli were normalized as a multiple of the M wave threshold. After normalization, the mean M recruitment curves, and similarly the fractions of motor axons activated, were equal in each group. In contrast, the mean H reflex amplitudes at the M threshold were different. The mean H reflex decrease, between 1.0 and 1.5 times the M threshold, was found to be the same fraction of the maximal H reflex amplitude in each group. The largest motor fibres, belonging to the largest motoneurones, are traditionally thought to have the lowest threshold for electrical excitation. Collision or retrograde inactivation should therefore preferentially affect the largest motoneurones, employed in only the largest H reflexes, at the lowest stimulus intensities. Our results are contrary to this hypothesis. Renshaw and/or Ib inhibition is likely to play a role in the initial decrease of the H reflex at higher stimulus intensities.

Pretarsal application of botulinum toxin for treatment of blepharospasm

The response to botulinum toxin type A was compared after two injection techniques in 45 patients with blepharospasm. Initially, patients were treated according to a triple injection technique; two injections into the upper eyelid and one injection into the lower eyelid. Subsequently, without altering the dose, the same patient group received two further injections into the pretarsal portion of the orbicularis oculi muscle of the upper lid. Triple injections were given in 227 treatments, of which 81% were successful. Mean duration of benefit was 8.5 weeks. Additional pretarsal injections were given in 183 treatment sessions. The number of successful treatments significantly increased, to 95% (P < 0.001), and the mean duration of benefit increased to 12.5 weeks (P < 0.001). Ptosis occurred significantly less often after pretarsal injections (P < 0.01). Patients with combined blepharospasm and involuntary levator palpebrae inhibition responded better to the pretarsal injection technique.

Motor neuron disease (amyotrophic lateral sclerosis) arising from longstanding primary lateral sclerosis

Three men were initially diagnosed as having primary lateral sclerosis (PLS), but eventually developed amyotrophic lateral sclerosis (ALS) after 7.5, 9, and at least 27 years. Non-familial ALS and PLS might be different manifestations of a single disease or constitute completely distinct entities. The clinical diagnosis of PLS predicts a median survival that is four to five times longer than in ALS.

Electromyography and recovery of the blink reflex in involuntary eyelid closure: a comparative study

Electromyographic (EMG) activity of orbicularis oculi and levator palpebrae muscles was recorded to study the origin of involuntary eyelid closure in 33 patients. The evoked blink reflex in all patients and in 23 controls was also studied. To examine the excitability of facial motoneurons and bulbar interneurons in individual patients and to compare the results with EMG findings, R1 and R2 recovery indices were calculated in all subjects, as the average of recovery values at 0.5, 0.3, and 0.21 second interstimulus intervals. Based on EMG patterns, the patients were divided into three subclasses: EMG subclass 1, 10 patients with involuntary discharges solely in orbicularis oculi muscle; EMG subclass 2, 20 patients with involuntary discharges in orbicularis oculi and either involuntary levator palpebrae inhibition or a disturbed reciprocal innervation between orbicularis oculi and levator palpebrae; EMG subclass 3, three patients who did not have blepharospasm, but had involuntary levator palpebrae inhibition in association with a basal ganglia disease. The total patient group showed an enhanced recovery of both R1 and R2 components compared with controls. Although 30 out of 33 patients had blepharospasm (EMG subclasses 1 and 2), R1 recovery index was normal in 64% and R2 recovery index was normal in 54%. Patients with an abnormal R2 recovery index had an abnormal R1 recovery index significantly more often. All patients from EMG subclass 1 had an abnormal R2 recovery index, whereas all patients from EMG subclass 3 had normal recovery indices for both R1 and R2 responses. Seventy five per cent of the patients from EMG subclass 2 had normal recovery indices. The results provide further evidence that physiologically blepharospasm is not a homogeneous disease entity, and indicate that different pathophysiological mechanisms at the suprasegmental, or segmental level, or both are involved.

Differential diagnosis in spinal and bulbar muscular atrophy clinical and molecular aspects

Kennedy disease is caused by an enlarged trinucleotide repeat sequence within the androgen receptor gene. We report here seven male patients with a benign motor neuron syndrome highly analogous to Kennedy disease but with a normal trinucleotide repeat.

Motor persistence of orbicularis oculi muscle in eyelid-opening disorders

We describe clinical and EMG findings in three patients with an inability to reopen the eyes after voluntary closure of the eyelids. Synchronous EMG recording from the levator palpebrae (LP) and orbicularis oculi (OrbOc) muscles revealed that after voluntary closure of the eyelids and upon the command to open the eyes, all three patients were unable to inhibit the "voluntary" contraction of the OrbOc muscles, while on clinical examination there was no evidence of ongoing OrbOc muscle contraction. This "motor persistence" was restricted predominantly to the pretarsal portion of the OrbOc. In one patient, it occurred as an isolated abnormality of the eyelid movement and was recorded as an additional EMG abnormality in two patients with blepharospasm and involuntary LP inhibition. Clinical examination alone cannot differentiate this type of disorder of supranuclear control of eyelid movement from involuntary LP inhibition; simultaneous EMG recording from the LP and OrbOc muscles is required. Injection of botulinum toxin into the pretarsal portion of OrbOc muscles is helpful.

Dopa-responsive dystonia and normalization of soleus H-reflex test results with treatment

We studied the ratio of the maximal H-reflex to maximal direct muscle potential (H/M ratio), late facilitation and late inhibition in the recovery curve, and vibratory inhibition of the soleus H-reflex in three consecutive patients with hereditary dopa-responsive dystonia, before and during treatment with levodopa. In one patient, we repeated the H-reflex tests twice after withdrawal of levodopa. The results were compared with those in a group of 48 healthy subjects. In the patients before treatment, the soleus H-reflex recovery curve showed increased late facilitation and depressed late inhibition, reflecting alterations in postsynaptic interneuronal activity. Vibratory inhibition, predominantly reflecting presynaptic inhibitory action, was depressed. Normalization of these test results occurred during levodopa treatment, concurrent with a clear clinical response. The H/M ratio, reflecting the excitability state of the motoneuron pool, was similar during and without levodopa treatment. In the one patient tested after levodopa withdrawal, enhancement of late facilitation and decrease of vibratory inhibition paralleled the reoccurrence of dystonia most clearly. Since soleus H-reflex tests mainly reflect mechanisms operating at the spinal level, spinal aminergic or dopaminergic systems are probably involved in dopa-responsive dystonia.

Soleus H-reflex tests in dystonia

Vibratory inhibition, the homonymous recovery curve and the ratio of the maximal H-reflex to direct muscle potential (H/M ratio) of the soleus H-reflex were assessed in 10 patients with leg dystonia and in six patients with arm or neck dystonia. The results were compared with those obtained in 48 healthy control subjects. H-reflex variables most helpful for the discrimination of patients and healthy subjects were identified. In patients with leg dystonia, vibratory inhibition was less marked than in control subjects, whereas late facilitation of the recovery curve was increased. In patients with leg dystonia, area values of test reflexes in the late facilitatory phase of the recovery curve exceeded peak-peak values, in contrast to findings in control subjects. This finding may be attributable to less synchronization of enhanced test reflexes in dystonia than in the control condition. In differentiating patients with leg dystonia from control subjects, a combination of parameters of vibratory inhibition and the late facilitatory phase of the recovery curve appeared most useful. In patients with arm or neck dystonia and in the unaffected legs of hemidystonic patients, soleus H-reflex test results were in the normal range. Abnormalities in the results of the soleus H-reflex tests we used appear to be related to the presence of clinical signs in the extremity under examination and not to the severity of features.

Abnormal eye movements in blepharospasm and involuntary levator palpebrae inhibition. Clinical and pathophysiological considerations

We report on four patients with involuntary eyelid closure and eye movement disorders. Three were healthy until the onset of their illness and one had a mild generalized choreoathetosis and dystonia due to kernicterus. Electromyographic recording revealed solely blepharospasm in two patients and blepharospasm in combination with involuntary levator palpebrae inhibition in the other two. The eye movement abnormalities were clinically characterized by inability to fix gaze and short or prolonged episodes of uncontrollable eye deviations accompanied, in two patients, by diplopia in horizontal or vertical directions. These episodes occurred independently of a disorder of eyelid movement. Eye movement recordings with a double magnetic induction technique showed saccadic intrusions in horizontal directions. They consisted of highly frequent square wave jerks in three and sporadic macro-square wave jerks in two patients. There were also episodes of extraocular muscle dystonia, commonly known as oculogyric crises, resulting in involuntary upward eye deviation in all patients and lateral deviation in three patients. In one patient, nasal-ward deviations were sometimes restricted to one eye. We conclude that these abnormal eye movements do not necessarily point to a symptomatic form of dystonia and that they may limit the beneficial effect of botulinum toxin or surgical intervention in the therapeutic management of involuntary eyelid closure. We suggest that either basal ganglia, especially substantia nigra pars reticularis and the brainstem structures, especially the paramedian pontine reticular formation, or both, may be involved in the pathogenesis of these abnormal movements.

Independence of soleus H-reflex tests in control and spastic subjects shown by principal components analysis

Different soleus H-reflex tests are used in the study of neurophysiological mechanisms of motor control. We studied the interdependence pattern of a number of soleus H-reflex tests, i.e., vibratory inhibition, the ratio of the reflex response to direct muscle potential (H/M ratio) and the homonymous recovery curve with a principal components analysis in 48 healthy controls and 38 patients with signs of the upper motoneuron syndrome. In controls, the analysis showed 3 independent principal components (PCs). Vibratory inhibition and H/M ratio loaded on separate components. Late facilitation and late inhibition variables of the recovery curve loaded on the third component due to the positive correlation (P < 0.001) between these variables. In spastic patients the analysis identified 4 independent PCs corresponding with vibratory inhibition, H/M ratio, late facilitation and late inhibition variables, respectively. The findings suggest that the mutual independence of the different soleus H-reflex tests in patients with the upper motoneuron syndrome has retained the control situation to a large extent.

Clinical and electromyographic features of levator palpebrae superioris muscle dysfunction in involuntary eyelid closure

We report on five patients with involuntary eyelid closure, diagnosed as blepharospasm and referred to use for treatment with botulinum A toxin. Synchronous electromyographic (EMG) recording was performed from the levator palpebrae superioris (LP) and the orbicularis oculi (OO) muscles. In the first two cases, EMG registration showed alternating, semirhythmic dystonic activities in both the LP and OO, clinically perceptible as "flickering" of the eyelids. While the eyelids were lowered, one of them also showed involuntary upper eyelid tractions due to dystonic activities of LP. In the third patient, EMG patterns were characterized by a gradual decrease in the level of LP activity, followed by the contraction of OO, which facilitated the return of LP to its tonic activity, termed "postinhibition potentiation" of LP. In the fourth patient, EMG recording showed involuntary inhibition of LP in combination with blepharospasm. Involuntary closure of the eyelids in the fifth patient was caused by short or prolonged periods of involuntary LP inhibition, whereas OO activity remained normal. Our results provide further evidence that LP muscle activities are regulated by burst-tonic motoneurons, and we suggest that these motoneurons, and/or the input signals regulating their activities, can be involved independently in a pathological process. Clinical symptoms are discussed that may be helpful to recognize those cases with LP motor dysfunction, whether or not accompanied by OO activity disorders. Because the term blepharospasm indicates an abnormal motor function of OO, we propose "blepharospasm-plus" to designate those cases with a combined motor dysfunction of LP and OO muscles.

Normalization of soleus H-reflex recruitment curves in controls and a population of spastic patients

We examined soleus H-reflex recruitment in 30 controls and 33 patients with spinal cord lesions and spastic spinal paresis. H-reflex gain and threshold were determined from recruitment curves after normalization of stimulus intensity as a multiple of the current for a threshold M-response. Reflex gain was expressed as the mean slope of the H-reflex recruitment curve up to the half-maximal response size. Up to this point the curve follows an almost linear trajectory and will mainly reflect Ia afferent stimulation. This slope had a large variability but was clearly correlated with the H/M ratio. The mean gain was equal in controls and patients. The relation between H- and M-thresholds was expressed as a ratio which had a lower mean value in the patients. Though both H- and M-thresholds may be influenced by peripheral factors, this lower ratio suggests an increase in spinal motoneuron excitability in patients.

Posterior tibial and sural nerve somatosensory evoked potentials: a study in spastic paraparesis and spinal cord lesions

In two groups of patients posterior tibial nerve (PTN) and sural nerve (SN) somatosensory evoked potentials (SEPs) were compared to each other and related to classified neurological signs. Group A consisted of 7 patients with hereditary spastic paraparesis (HSP) and 8 with primary lateral sclerosis (PLS), with solely or primarily motor deficits. Group B consisted of 12 patients with different spinal cord diseases causing variable mixed sensory and motor impairments. Normal values were derived from 39 controls. A clear trend towards more frequently prolonged PTN SEP than SN SEP latencies was found in both groups and appears to make PTN SEPs more useful for clinical application than SN SEPs. No significant differences were found in SEP abnormalities when the two patient groups were compared to each other. No relationships were found between SEP abnormalities and spasticity, weakness or any single sensory modality, making the two SEPs questionable as a quantitative test for neurological deficits in our patients.

Soleus H-reflex tests and clinical signs of the upper motor neuron syndrome

Soleus H-reflex tests are used for elucidating pathophysiological mechanisms in motor control. The cumulative vibratory inhibition of the soleus H-reflex, the ratio of the reflex to direct muscle potential (H to M ratio) and the recovery curve of the soleus H-reflex were studied in 38 patients with varying signs of the upper motor neuron syndrome for a possible relation with clinical features. The results were compared with those obtained from a group of healthy volunteers. The magnitude of vibratory inhibition decreased with increase of hypertonia. The H to M ratio increased as the activity of the tendon reflex was enhanced and correlated to a lesser degree with muscle tone. Both the H to M ratio and late facilitation of the soleus H-reflex recovery curve were elevated in clonus. The findings suggest that alterations in the results of soleus H-reflex tests relate to specific clinical features of the upper motor neuron syndrome. Possible pathophysiological implications are discussed.

Posterior tibial nerve somatosensory evoked potentials in slowly progressive spastic paraplegia: a comparative study with clinical signs

Clinical and neurophysiological examinations were performed on seven patients with hereditary spastic paraplegia and on eight patients with primary lateral sclerosis. The results were compared with those obtained from a group of 39 control subjects. Prolonged latency times and decreased amplitudes of the posterior tibial nerve (PTN) somatosensory evoked potentials (SEPs) were found in the majority of the patients. The SEP changes occurred without sensory impairment or with loss of vibration sense only. There was no significant relation between the PTN SEP abnormalities and the severity of pyramidal signs for the whole patient group, nor longitudinally for the individual subjects. Analyses of PTN SEPs in patients suffering from slowly progressive spastic paraplegia (SP), therefore, seem to be a method to indicate a feature of spinal cord dysfunction that is not related to the severity of clinical signs. Considering the neuropathology of the spinal cord in SP patients, we furthermore argue that the ascending spinal pathway involved in conducting impulses for PTN SEPs probably uses other routes as well as the funiculus gracilis.

Hereditary protein S deficiency presenting with cerebral sinus thrombosis in an adolescent girl

A 14-year-old girl, on oral contraceptives for 3 months, presented with cerebral sinus thrombosis. Investigation revealed underlying hereditary protein S deficiency. This uncommon cause of cerebral sinus thrombosis and the possible association with oral contraceptives are discussed.

Effects of brainstem lesions on the masseter inhibitory reflex. Functional mechanisms of reflex pathways

The masseter inhibitory reflex (MIR) was investigated in 16 patients with localized brainstem lesions involving the trigeminal system. The MIR consists of two phases of EMG silence (S1 and S2) evoked by stimulation of the mental nerve during maximal clenching of the teeth. The extent of the lesions was assessed by neurological examination, nuclear magnetic resonance imaging (MRI), and recording of trigeminal reflexes with known paths (jaw jerk and blink reflex). The MIR appeared to be abnormal in lesions involving the pontine tegmentum, from the pontomedullary junction to midpons, and some lesions selectively affected one component of the MIR, proving that S1 and S2 are relayed by independent circuits. The results indicate that afferent fibres for S1, which reach the pons via the trigeminal sensory root, enter the ipsilateral trigeminal spinal tract and terminate at the level of the midpons; impulses are then relayed by interneurons to the ipsilateral and contralateral trigeminal motor nuclei. The afferent fibres for S2 follow a similar path, but descend to the pontomedullary junction; at this level impulses are conducted along bilateral interneuronal paths, which probably ascend through the lateral reticular formation, before connecting with the trigeminal motor nucleus on either side. Analysis of MIR recordings can be of particular value because brainstem inhibitory reflexes cannot be tested by clinical examination.

Intramedullary spinal cord metastasis following a slowly progressive course

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Cumulative vibratory indices and the H/M ratio of the soleus H-reflex: a quantitative study in control and spastic subjects

Suppression of the soleus (Sol) H-reflex recruitment curve by Achilles tendon vibration and the ratio of maximum Sol H-reflex (Hmax) to maximum M-response (H/M ratio) have been studied by means of computer processing on the basis of peak-to-peak (P-P) and area values in 46 controls and in 16 spastic patients. The 'classical' vibratory index (VI) has been compared with a new cumulative VI (CVI), which is defined as the quotient of the surface under the recruitment curve obtained with vibration and the one obtained without vibration up to an equal intensity level. Statistical analyses were performed from threshold to 3 different intensity levels. Tendon vibration is found to be less effective at higher intensity levels. Mean values with S.D.s of CVIs at Hmax intensity are significantly lower than those of the 'classical' VIs. VIs increase with age while H/M ratios decline. Stepwise discriminant analyses showed that area CVI at Hmax intensity yielded the best distinction between controls and patients. Additional differential contribution is obtained by P-P H/M ratio. A canonic variable derived from these two variables correctly classified 44 out of 46 controls and 15 out of 16 patients. The methods presented improve the specificity of the quantitative neurophysiological measure of spasticity by means of Sol H-reflex recordings.

Drug therapy in continuous ambulatory peritoneal dialysis patients

Transport of solutes across the peritoneal membrane in continuous ambulatory peritoneal dialysis (CAPD) is determined by patient-related factors (concentration gradient, membrane surface area, blood flow and membrane permeability) and by drug-related factors (charge on the molecule, protein binding, molecular weight, lipophilicity). On the basis of the chemical properties of a drug a prediction of the peritoneal clearance rate in CAPD patients is given, by the formula CLCAPD = 75 square root free fraction/molecular weight. The implications of this formula are discussed. It is concluded that usually it is not necessary to change the dose as compared with end-stage renal disease patients who are not treated with CAPD.