Gait dynamics in Parkinson's disease: relationship to Parkinsonian features, falls and response to levodopa

OBJECTIVES

Patients with Parkinson's disease (PD) have an increased risk of falling that has yet to be fully explained. To better understand the gait disturbance in PD and the factors that contribute to falls, we quantitatively evaluated: (1) the relationship between gait variability (a marker of fall risk in other populations), fall history, and other parkinsonian features, and (2) the effects of levodopa on these relationships.

METHODS

The average stride time and stride-to-stride variability were measured using force-sensitive insoles during comfortable walking. Fall frequency, motor control, function, and mental health were measured using the Unified Parkinson's Disease Rating Scale (UPDRS), the Mini-Mental State Exam (MMSE), and the timed motor tests of the Core Assessment Program for Intracerebral Transplantations (CAPIT) in 32 subjects with idiopathic PD, in an "off" (unmedicated) state and again in an "on" (medicated) state.

RESULTS

Average stride time was not associated with any UPDRS or CAPIT measure and was similar in fallers and non-fallers in "off" and "on" states (p>0.27). Stride time variability was significantly associated with fall frequency as well as with total scores on the CAPIT and the UPDRS, ADL abilities, and motor function. Stride time variability and falls were not related to tremor, rigidity or bradykinesia in the "off" state. 41% of subjects reported one or more falls. Stride time variability was 8.8+/-7.9% in fallers and 4.2+/-1.3% in non-fallers (p<0.009). Stride time variability significantly improved in response to levodopa, both in fallers and non-fallers, but remained increased in fallers (vs. non-fallers).

CONCLUSIONS

The patho-physiology responsible for impaired stride-to-stride regulation of gait timing is apparently independent of other cardinal features of PD, i.e., tremor, rigidity, or bradykinesia, but is responsive to levodopa. Stride-to-stride variability is especially impaired among PD subjects with a history of falls, suggesting, for the first time, the possibility of exaggerated impairment of internal clock function in PD fallers.

A double-blind randomised placebo-controlled evaluation of three doses of botulinum toxin type A (Dysport) in the treatment of spastic equinovarus deformity after stroke

BACKGROUND/OBJECTIVES

Calf muscle hypertonicity following stroke may impair walking rehabilitation. The aim of this study was to assess botulinum toxin (Dysport) in post-stroke calf spasticity.

METHODS

A prospective, multicentre, double-blind, placebo-controlled, dose-ranging study was performed to evaluate dysport at 500, 1,000 or 1,500 units in 234 stroke patients. They were assessed at 4-week intervals over 12 weeks.

RESULTS

The primary outcome measure, 2-min walking distance and stepping rate increased significantly in each group (p < 0.05, paired test), but there was no significant difference between groups (including placebo). Following dysport treatment, there were small but significant (p = 0.0002-0.0188) improvements in calf spasticity, limb pain, and a reduction in the use of walking aids, compared to placebo. Investigators' and patients' assessments of overall benefit suggested an advantage for dysport over placebo, but this was not significant. Sixty-eight patients reported 130 adverse events, with similar numbers in each group. The few severe events recorded were not considered to be treatment-related.

CONCLUSION

Dysport resulted in a significant reduction in muscle tone, limb pain and dependence on walking aids. The greatest benefits were in patients receiving dysport 1,500 units, but 1,000 units also had significant effects. Dysport 500 units resulted in some improvements. Since few adverse events were reported, this therapy is considered safe and may be a useful treatment in post-stroke rehabilitation of the leg. Possible reasons why functional improvements in gait parameters were not observed are also discussed.

Characterization of freezing of gait subtypes and the response of each to levodopa in Parkinson's disease

To assess the effect of levodopa on distinct freezing of gait (FOG) subtypes in patients with 'off' FOG. Nineteen patients (12 men, mean age 62.0 +/- 8.4 years) with Parkinson's disease and clinically significant FOG during 'off' states were videotaped whilst walking 130 m during 'off' and 'on' states. Three independent observers characterized the type, duration, and clinical manifestations and quantified FOG by analyzing the videotapes. Their combined mean scores were used for statistical analysis. The intra-class correlation coefficient assessed inter-observer reliability. Wilcoxon and Friedman tests evaluated differences in mean frequencies of FOG characteristics. During 'off' states, FOG was elicited by turns (63%), starts (23%), walking through narrow spaces (12%) and reaching destinations (9%). These respective values were only 14, 4, 2 and 1% during 'on' states (P < 0.011). Moving forward with very small steps and leg trembling in place were the most common manifestations of FOG; total akinesia was rare. Most FOG episodes took <10 s and tended to be shorter during 'on' states. Levodopa significantly decreased FOG frequency (P < 0.0001) and the number of episodes with akinesia (P < 0.001). Distinction amongst FOG subtypes enables evaluation of distinctive therapeutic response. Levodopa helps in reducing the frequency and duration of 'off'-related FOG.

Impaired regulation of stride variability in Parkinson's disease subjects with freezing of gait

Patients with Parkinson's disease (PD) often experience freezing of gait, a debilitating phenomenon during which the subject suddenly becomes unable to start walking or to continue to move forward. Little is known about the gait of those subjects with PD who experience freezing of gait or the pathophysiology of freezing. One possibility is that freezing of gait is a truly paroxysmal phenomenon and that the usual walking pattern of subjects who experience freezing of gait is not different than that of other patients with PD who do not experience these transient episodes of freezing of gait. On the other hand, a recent study noted gait changes just prior to freezing and concluded that dyscontrol of the cadence of walking contributes to freezing. To address this question, we compared the gait of PD subjects with freezing of gait to PD subjects without freezing of gait. Given the potential importance of the dyscontrol of the cadence of walking in freezing, we focused on two aspects of gait dynamics: the average stride time (the inverse of cadence, a measure of the walking pace or rate) and the variability of the stride time (a measure of "dyscontrol," arrhythmicity and unsteadiness). We found that although the average stride time was similar in subjects with and without freezing, stride-to-stride variability was markedly increased among PD subjects with freezing of gait compared to those without freezing of gait, both while "on" (P<0.020) and "off" (P<0.002) anti-parkinsonian medications. Further, we found that increased gait variability was not related to other measures of motor control (while off medications) and levodopa apparently reduced gait variability, both in subjects with and without freezing. These results suggest that a paradigm shift should take place in our view of freezing of gait. PD subjects with freezing of gait have a continuous gait disturbance: the ability to regulate the stride-to-stride variations in gait timing and maintain a stable walking rhythm is markedly impaired in subjects with freezing of gait. In addition, these findings suggest that the inability to control cadence might play an important role in this debilitating phenomenon and highlight the key role of dopamine-mediated pathways in the stride-to-stride regulation of walking.

Effects of subthalamic nucleus stimulation and levodopa treatment on gait abnormalities in Parkinson disease

BACKGROUND

Stimulation of the subthalamic nucleus is proposed for the treatment of patients presenting with severe Parkinson disease. The effect on gait is not clearly established.

OBJECTIVES

To evaluate objectively the influence of bilateral subthalamic nucleus stimulation on gait in Parkinson disease and to compare it with the effects of levodopa treatment.

METHODS

Ten patients underwent bilateral subthalamic nucleus stimulation. The preoperative and postoperative (3 months after surgery) clinical gait disturbances, as well as spatial and temporal gait parameters, were analyzed in off and on-drug conditions. The gait analysis was performed using a video motion analysis system (optoelectronic VICON system; Oxford Metrics, Oxford, England).

RESULTS

In the off condition, there was an improvement after surgery for the total motor score and the gait subscore. In the on-drug condition, there was an improvement in levodopa-induced dyskinesias and the motor score, whereas the gait subscore was unchanged. For the gait parameters measured by the video motion analysis system system, there was also an improvement in the off condition and to a lesser extent in the on-drug condition.

CONCLUSIONS

Our method allowed exact quantification of the benefit of surgery on gait parameters. Compared with the levodopa treatment, the effect of stimulation on gait kinematic parameters seems to be qualitatively similar but quantitatively different with a lower benefit on gait velocity and stride length. Concerning the pathophysiology of gait troubles in Parkinson disease, the deficit in control of stride length would be the fundamental deficit. The study underlines the possible role of the subthalamic nucleus on the stride length regulation.

The natural history of the syndrome of primary progressive freezing gait

BACKGROUND

Primary progressive freezing gait disorder is considered to be a distinct clinical entity that manifests predominantly as a progressive freezing gait disorder without accompanying abnormalities. However, confusion remains about its clinical presentation, natural history, and classification.

OBJECTIVE

To examine the natural history, clinical and brain imaging characteristics, and response to dopaminergic medications of primary progressive freezing gait (PPFG) disorder.

DESIGN/METHODS

Review of medical records, videotape examinations, and computed tomographic and magnetic resonance imaging of the brain and results of neurological evaluations, including the Unified Parkinson's Disease Rating Scale, in patients with PPFG.

RESULTS

Thirty patients (16 male) were diagnosed as having PPFG (mean age at onset, 72.2 years; mean duration of disease, 5 years). Gait disorder was the initial complaint in 27 patients. Freezing gait was the initial manifestation in 18 and was present within the first year in 27. Natural history included 25 patients falling within 3 years of onset, 20 experiencing retropulsion within 4 years, and 16 requiring wheelchairs by 5 years. On neurological examination, bradykinesia was present in 29 patients, muscle rigidity in 15, and postural tremor in 11. Other features included speech abnormalities in 10, hyperreflexia without clonus in 17, and dementia in 8. Extraocular movement abnormalities and dysphagia were rare. All 30 patients were treated with levodopa with minimal effect. Eighteen were treated with a dopamine agonist with no notable effect. Of the 23 patients with magnetic resonance imaging scans, results were normal in 9 and included minor nonspecific changes in 14. The computed tomographic scans obtained in 12 patients showed similar results. One patient underwent fluorine F ((18)F) labeled deoxyglucose positron emission tomography, which showed mild reduction in medial frontal glucose metabolism.

CONCLUSIONS

Primary progressive freezing gait appears to be a clinically distinct progressive neurological disorder that primarily affects gait, initially resulting in freezing and later in postural instability. A wheelchair-bound state often develops within 5 years. It is accompanied by other parkinsonian features, particularly bradykinesia, but is unresponsive to dopaminergic medications. It progresses in a fairly stereotyped manner. Primary progressive freezing gait disorder should be a unifying term for this disorder that has gone by many names in the literature and should be classified as a Parkinson-plus disorder.

Behavioral effects of chronic melatonin and pregnenolone injections in a myelin mutant rat (taiep)

The taiep (tremor, ataxia, immobility, epilepsy, and paralysis) myelin mutant displays a number of locomotor deficits. Taiep rat gait is characterized by shorter stride and step lengths as well as by larger stride widths. Thirty-day-old taiep mutants were placed under a regimen of daily hormone injections for 60 days. Animals in Condition 1 received melatonin, those in Condition 2 received pregnenolone sulfate, and those in a third control condition received injections of saline. Following the injections, each taiep mutant's gait was analyzed. The animals that received melatonin and pregnenolone displayed significantly larger stride and step lengths than did the controls. In addition, the animals that received hormones displayed shorter stride widths than did the controls. These experimental effects are consistent with a normalization of gait. Possible cellular mechanisms of this behavioral effect are discussed.

Effect of bilateral subthalamic nucleus stimulation on parkinsonian gait

Clinical reports show that bilateral subthalamic nucleus (STN) stimulation is effective in improving parkinsonian gait. Quantitative analysis of the efficacy of STN stimulation on gait is of interest and can be carried out using a commercially available stride analyser. Ten parkinsonian patients (5 men, 5 women) with a mean age of 55.8, SD 9.6 years were included in our study. They had a mean duration of Parkinson's disease (PD) of 13.3, SD 4.5 years and a motor examination score (part III of the Unified Parkinson's Disease Rating Scale) (UPDRS) of 43, SD 13 in off-stimulation off-drug condition. All the patients had bilateral chronic STN stimulation which had started from 3 to 36 months before the study. Patients were evaluated in off-drug and on-drug conditions both with and without stimulation. We analysed the principal gait measures: velocity, cadence, stride length, gait cycle, duration of single and double limb support. The clinical parkinsonian signs were evaluated with the part III of the UPDRS. In the off-drug condition, STN stimulation significantly (p < 0.05) improved velocity and stride length. The effect was similar to that of levodopa. When STN stimulation was switched on at the best of the levodopa induced effect, no further improvement was observed. The UPDRS motor score was significantly (p < 0.001) decreased after both stimulation and levodopa. In conclusion, STN stimulation is effective on parkinsonian gait.

Kinematic and kinetic evaluation of the ankle after intramuscular injection of botulinum toxin A in children with cerebral palsy

Intramuscular botulinum toxin A (BTA) injection has a role in the conservative management of dynamic equinus deformity in children with cerebral palsy. The effect of BTA injection of the gastrocsoleus muscle during gait was evaluated. Eight children with hemiplegia (median age 4.4 years, range 2 to 8 years) were included in this retrospective study. Assessment included kinematic and kinetic gait analysis before and after (median 57.5 days) treatment. Postinjective kinematics showed significant improvement of ankle range of motion in the stance phase of gait. Ankle kinetics demonstrated a significant decrease of pathological power generation in midstance. The ankle power quotient (APQ) was also significantly improved. Ankle power in terminal stance was improved, although not to a significant level. These results provide evidence of normalization of energy production at the ankle, which is critical for normal gait. The effect of BTA is temporary and can be successfully repeated. This allows deferring the need for surgical intervention until the child is older and recurrence rate is lower.

Vasopressin-deficient rats exhibit sensorimotor gating deficits that are reversed by subchronic haloperidol

BACKGROUND

Brattleboro (BB) rats are Long Evans rats with a single base pair genetic mutation that impairs their ability to synthesize vasopressin, a neurotransmitter and neurohormone. Brattleboro rats are known to have deficits in memory, emotional reactivity, motivation, attention, and social recognition, abnormalities associated with schizophrenia. Prepulse inhibition (PPI) of the acoustic startle reflex (ASR) is a measure of sensorimotor gating. Prepulse inhibition is deficient in unmedicated schizophrenia patients, and PPI deficits in schizophrenia may be related to the cognitive and behavioral abnormalities associated with this disorder. In this study we tested the hypothesis that BB rats exhibit PPI deficits analogous to those exhibited by schizophrenia patients.

METHODS

In one experiment, BB rats homozygous (BB-Ho) or heterozygous (BB-Hz) for the mutated vasopressin gene were compared with normal Long Evans (LE) rats from the same breeder source. In separate studies, BB-Ho and LE rats were treated with acute or subchronic (22 days) injections of haloperidol.

RESULTS

Both BB-Ho and BB-Hz rats had significantly higher ASR and significantly lower PPI compared with LE rats, with BB-Ho rats exhibiting the lowest PPI among all three genotypes. Furthermore, a single subcutaneous (SC) injection of haloperidol (0.5 mg/kg) did not reverse the PPI deficits in BB rats. In contrast, daily SC administration of haloperidol for 22 days reversed PPI deficits in BB rats.

CONCLUSIONS

These results suggest that PPI deficient BB rats may be an important genetic model of PPI deficits, which may help elucidate genetic, pharmacologic, and pathophysiologic mechanisms underlying PPI deficits and the effects of antipsychotic drugs on PPI.

Amantadine increases gait steadiness in frontal gait disorder due to subcortical vascular encephalopathy: a double-blind randomized placebo-controlled trial based on quantitative gait analysis

In a randomized, double-blind placebo-controlled trial, 40 patients diagnosed as subcortical vascular encephalopathy (SVE) were given a daily dose of 500 ml i.v. amantadine vs. placebo for 5 days. Both groups were treated with physiotherapy on a daily basis. Quantitative gait analyses were performed at days 1 and 6 to evaluate gait steadiness from cadence, length of heel-to-toe movements, variability of centre of gravity (COG) and double support time. Both placebo- and amantadine-receiving patient groups showed mild improvement in gait parameters after study, which failed to show the superiority of amantadine, when comparing drug-induced changes between both groups. However, analysing the treatment effects from day 0 to day 6 in both groups separately, statistically significant changes could be found in the amantadine group for cadence, length of heel-to-toe movements in single support phase as well as for variability in double support phase and double support time (two-tailed paired t-test, p < 0.05), whereas in the placebo group, a statistically significant effect could only be seen for double support time (p < 0.05). In this small pilot study, amantadine tends to improve gait steadiness as evaluated by cadence, length of heel-to-toe movements in single support phase, variability in double support phase and double support time, in patients with moderate frontal gait disorder due to SVE. Improvements in the placebo group can be interpreted as physiotherapy effect, which improved gait steadiness slightly, however, this was statistically significant only for double support time.

The effect of botulinum toxin injections to the calf muscles on freezing of gait in parkinsonism: a pilot study

BACKGROUND

Freezing of gait (FOG) is a common and very disabling parkinsonian symptom, which is poorly understood and responds unsatisfactorily to medical treatment. We recently reported a unique patient with Parkinson's disease (PD) who had significant alleviation of FOG shortly after she was injected with botulinum toxin type A (BTX-A) for foot dystonia (Giladi et al. 1997).

OBJECTIVE

To assess the effect of BTX-A injections into the calf muscles of parkinsonian patients on FOG.

METHOD

BTX-A was injected in an open fashion into the calf muscles of 10 parkinsonian patients (age 55-75 years) with FOG as a predominant symptom. Response of FOG was assessed subjectively by the patient from worsening (-1) to marked improvement (+3). One patient was injected in a single blind fashion with saline or BTX-A after he had an initial good response.

RESULTS

Seven patients reported different rates of improvement of FOG severity in 15 out of 17 therapeutic sessions. Four patients (40%) reported marked improvement (+3) of FOG in 5 sessions. Two patients reported no effect in two sessions. The mean duration of improvement was 6 weeks (range 1-12 weeks) with definite deterioration afterwards. The patient who was injected in a single blind fashion did not respond to saline injections but improved significantly with BTX-A treatment.

CONCLUSIONS

We observed a clear temporal relationship between BTX-A injections into the calf muscles of parkinsonian patients and improvement of FOG. A double blind placebo controlled prospective study is needed before any conclusions can be drawn about the role of BTX-A injection in FOG.

Amelioration of frozen gait by tandospirone, a serotonin 1A agonist, in a patient with pure akinesia developing resistance to L-threo-3,4-dihydroxyphenylserine

A 71-year-old woman presented with severe akinesia, frozen gait, and compromised postural reflexes, without rigidity, tremor, or vertical gaze disturbance. With a working diagnosis of pure akinesia, we administered amantadine (150 mg/d) and L-threo-3,4-dihydroxyphenylserine (DOPS) (600 mg/d), which alleviated her symptoms. When frozen gait recurred 2 months later, we increased the dose of L-threo-DOPS to 900 mg/d and added levodopa (300 mg/d) combined with carbidopa, but this failed to improve the patient's symptoms. We then combined administration of tandospirone, a serotonin (5-HT) 1A agonist with L-threo-DOPS (600 mg/d), resulting in marked clinical improvement. Tandospirone is reported to activate noradrenergic neurons via the 5-HT 1A receptor, which could account for such striking improvement in a patient previously responsive to the noradrenergic precursor L-threo-DOPS given alone.

[Treatment of the spastic drop foot with botulinum toxin type A in adult patients]

Spastic drop foot can be managed by physical measures, local pharmacological agents, oral anti-spastic drugs and surgical procedures. Recent studies have documented the clear effect of botulinum toxin type A (BTX-A) in the treatment of the spastic drop foot, particularly by reducing the resistance against passive movement and increasing the range of motion. Functional benefit and pain reduction have also been observed. The use of BTX-A is safe and free of serious side effects. Individual realistic treatment goals must be defined by the rehabilitation team before the treatment. Possible purposes of the treatment are the achievement of a straight foot to allow weight bearing or application of an orthosis and to reduce the premature activation of the calf muscles during gait. Other treatment goals are the facilitation of nursing care, as well as physical and occupational therapy. BTX-A injections can reduce pain, and prevent pressure ulcers or surgical interventions. Early physiotherapy or occupational therapy may increase the treatment effect of BTX-A. Close cooperation between the neurologist, physiotherapist, occupational therapist, nursing staff and other multidisciplinary rehabilitation team members is essential to maximize the benefit for the patients.

Agmatine improves locomotor function and reduces tissue damage following spinal cord injury

Clinically effective drug treatments for spinal cord injury (SCI) remain unavailable. Agmatine, an NMDA receptor antagonist and inhibitor of nitric oxide synthase (NOS), is an endogenous neuromodulator found in the brain and spinal cord. Evidence is presented that agmatine significantly improves locomotor function and reduces tissue damage following traumatic SCI in rats. The results suggest the importance of future therapeutic strategies encompassing the use of single drugs with multiple targets for the treatment of acute SCI. The therapeutic targets of agmatine (NMDA receptor and NOS) have been shown to be critically linked to the pathophysiological sequelae of CNS injury and this, combined with the non-toxic profile, lends support to agmatine being considered as a potential candidate for future clinical applications.

Riluzole and methylprednisolone combined treatment improves functional recovery in traumatic spinal cord injury

The potential use of riluzole (a glutamate release inhibitor) alone or in combination with methyl-prednisolone (MP) in treating acute spinal cored injury (SCI) was examined. Rats received a contusion injury to the spinal cord using the NYU impactor and were treated with vehicle, riluzole (8 mg/kg), MP(30 mg/kg), or riluzole + MP at 2 and 4 h following injury. Animals continued to receive riluzole treatment (8 mg/kg) for a period of 1 week. The animals were then tested weekly for functional recovery using the BBB open field locomotor score. At the end of testing (6 weeks after injury), each spinal cord was examined for the amount of remaining tissue at the injury site and a myelination index was used to quantify remaining axons in the ventromedial white matter. In this study, only the combination treatment was found to significantly improve behavioral recovery as assessed using the BBB open field locomotor scale. In addition, the combination treatment promoted tissue sparing at the lesion epicenter, but had no clear effect on the index of myelination. The results of this study clearly demonstrate the potential beneficial effects of a combination approach in the treatment of traumatic SCI.

Effect of baclofen on gait in spastic MS patients

OBJECTIVES

To measure gait and postural stability by objective methods in spastic MS patients and to evaluate the effect of baclofen on gait and postural stability.

PATIENTS AND METHODS

Fourteen spastic MS patients were examined in a placebo controlled double-blind, cross-over trial of oral baclofen treatment. The gait was measured on a computerized treadmill and postural stability was measured on a computer assisted force-plate.

RESULTS

Only insignificant improvements in the clinical measurements during baclofen treatment were found. At baseline gait was characterized by low speed, short steps and unsteadiness. Postural stability was severely impaired. During baclofen treatment only vertical unsteadiness of gait diminished significantly.

DISCUSSION

We conclude that patients primarily with spasticity, concomitant with hampering or painful spasms and co-contractions should be offered treatment with baclofen. Only some will experience improvement of their gait disorders, when treated with baclofen.