Camille Carroll

Cannabis for dyskinesia in Parkinson disease A randomized double-blind crossover study

Background: The long-term treatment of Parkinson disease (PD) may be complicated by the development of levodopa-induced dyskinesia. Clinical and animal model data support the view that modulation of cannabinoid function may exert an antidyskinetic effect. The authors conducted a randomized, double-blind, placebo-controlled crossover trial to examine the hypothesis that cannabis may have a beneficial effect on dyskinesia in PD. Methods: A 4-week dose escalation study was performed to assess the safety and tolerability of cannabis in six PD patients with levodopa-induced dyskinesia. Then a randomized placebo-controlled crossover study (RCT) was performed, in which 19 PD patients were randomized to receive oral cannabis extract followed by placebo or vice versa. Each treatment phase lasted for 4 weeks with an intervening 2-week washout phase. The primary outcome measure was a change in Unified Parkinson’s Disease Rating Scale (UPDRS) (items 32 to 34) dyskinesia score. Secondary outcome measures included the Rush scale, Bain scale, tablet arm drawing task, and total UPDRS score following a levodopa challenge, as well as patient-completed measures of a dyskinesia activities of daily living (ADL) scale, the PDQ-39, on-off diaries, and a range of category rating scales. Results: Seventeen patients completed the RCT. Cannabis was well tolerated, and had no pro- or antiparkinsonian action. There was no evidence for a treatment effect on levodopa-induced dyskinesia as assessed by the UPDRS, or any of the secondary outcome measures. Conclusions: Orally administered cannabis extract resulted in no objective or subjective improvement in dyskinesias or parkinsonism.

Association of the H63D polymorphism in the hemochromatosis gene with sporadic ALS

Iron misregulation promotes oxidative stress and abnormally high iron levels have been found in the spinal cords of patients with ALS. The authors investigated whether HFE gene polymorphisms, linked to hemochromatosis, are associated with ALS using two independent populations of patients with sporadic ALS and controls (totaling 379 patients and 400 controls). They found that the H63D polymorphism is overrepresented in individuals with sporadic ALS (odds ratio 1.85, CI: 1.35 to 2.54).

The effect of cannabis on tremor in patients with multiple sclerosis.

Background: Disabling tremor is common in patients with multiple sclerosis (MS). Data from animal model experiments and subjective and small objective studies involving patients suggest that cannabis may be an effective treatment for tremor associated with MS. To our knowledge, there are no published double-blind randomized controlled trials of cannabis as a treatment for tremor in MS patients. Methods: The authors conducted a randomized double-blind placebo-controlled crossover trial to examine the effect of oral cannador (cannabis extract) on 14 patients with MS with upper limb tremors. There were eight women and six men, with a mean age of 45 years and mean Expanded Disability Status Scale score of 6.25. Patients were randomly assigned to receive each treatment and the doses escalated over a 2-week period before each assessment. The primary outcome was change on a tremor index, measured using a validated tremor rating scale. The study was powered to detect a functionally significant 50% improvement in the tremor index. Secondary outcomes included accelerometry, an ataxia scale, spiral drawing, finger tapping, and nine-hole pegboard test performance. Results: Analysis of the data showed no significant improvement in any of the objective measures of upper limb tremor with cannabis extract compared to placebo. Finger tapping was faster on placebo compared to cannabis extract (p < 0.02). However, there was a nonsignificant trend for patients to experience more subjective relief from their tremors while on cannabis extract compared to placebo. Conclusions: Cannabis extract does not produce a functionally significant improvement in MS-associated tremor.

Stroke in Devon: knowledge was good, but action was poor.

Background and aim: Effective implementation of early treatment strategies for stroke requires prompt admission to hospital. There are several reasons for delayed admission. Good awareness should facilitate early admission. We identified local targets for education. Methods: Four groups, each of 40 people, completed questionnaires to determine their knowledge of stroke symptoms and risk factors, and the action they took or would take in the event of a stroke. The groups were: patients with a diagnosis of stroke or TIA (within 48 hrs of admission); patients at risk of stroke; the general population; and nurses. Results: Forty per cent of stroke patients identified their stroke. Median time from onset of symptoms to seeking medical help was 30 minutes. Medical help was sought by the patient themselves in only 15% of cases. In 80% of cases the GP was called rather than an ambulance. Of the at risk group, 93% were able to list at least one symptom of acute stroke, as were 88% of the general population. An ambulance would be called by 73% of the at risk group in the event of a stroke. Patients with self reported risk factors for stroke were largely unaware of their increased risk. Only 7.5% of at risk patients acquired their stroke information from the medical profession. Conclusions: Public knowledge about stroke is good. However, stroke patients access acute services poorly. At risk patients have limited awareness of their increased risk. A campaign should target people at risk, reinforcing the diagnosis of stroke and access to medical services.

Reversal of parkinsonian symptoms by intrastriatal and systemic manipulations of excitatory amino acid and dopamine transmission in the bilateral 6-OHDA lesioned marmoset.

We have investigated the potential of alleviating parkinsonian symptoms by manipulating excitatory amino acid (EAA) transmission, by several different pharmacological means, in a novel primate model of parkinsonism. The model is based on a two-stage bilateral 6-hydroxydopamine lesion procedure in marmosets, which produces a stable but marked parkinsonian condition. Parkinsonian symptoms were reversed in a dose-dependent manner by systemic administration of levodopa and intrastriatal injections of apomorphine administered into either the caudate nucleus or the putamen. (R)-HA-966, a partial agonist for the NMDA receptor associated glycine site, also alleviated parkinsonian symptoms when injected intrastriatally but not when injected systemically. Systemic injection of enadoline, a kappa opiate which blocks release of EAAs, reduced parkinsonian symptoms when injected systemically, though it did not restore completely normal motor behaviour. In contrast, ifenprodil, an antagonist for the NMDA receptor-associated polyamine modulatory site, when injected systemically at an optimal dose, resulted in apparently normal motor behaviour. These data suggest that attenuation of EAA transmission could be used to treat parkinsonism.

Visual fields in patients with posterior GPi pallidotomy

The objective of this study was to describe the incidence and types of visual field defects after posterior globus pallidus internus (GPi) pallidotomy for Parkinsons disease. The creation of the pallidotomy lesion carries a risk of damaging neighboring structures such as the optic tract. The reported frequency of visual field defects in patients after pallidotomy varies from 0 to 40%. Goldmann visual field testing was performed on 40 patients who underwent microelectrode-guided posterior GPi pallidotomy. The optic tract was identified during the procedure by listening during microelectrode recording for the evoked responses to light flashes and by assessing stimulation-induced subjective responses. After the first 18 patients, lesioning thresholds were increased from 0.5 to ≥1.0 mA so that the lesion was placed more distant from the optic tract. The location of individual lesions was determined on postsurgical MRI. Three patients (7.5%) had visual field defects likely related to the pallidotomy. These were contralateral homonymous superior quadrantanopias, associated in two patients with small paracentral scotomas. The incidence of visual field defects with the early technique was 11% (2/18) and decreased to 4.5% (1/22) after thresholds for lesioning were increased. Except for the location of the lesion relative to the optic tract (more ventral, adjacent to or extending into the optic tract), no other variable correlated with a post-pallidotomy visual field defect. Microelectrode-guided GPi pallidotomy is a relatively safe procedure as regards visual function even when the optic tract is used as a guide for lesion placement.

Neurochemical and behavioural investigations of the NMDA receptor-associated glycine site in the rat striatum : functional implications for treatment of parkinsonian symptoms

The glutamatergic cortico-striatal and subthalamo-entopeduncular pathways are both overactive in parkinsonism. Previous behavioural investigations have shown that intra-entopeduncular injection of either NMDA-site or glycine-site antagonists results in alleviation of parkinsonian symptoms, although injection of the former is associated with the appearance of anaesthetic-like side effects. These behavioural differences may be mediated by action on different NMDA receptor subtypes. Recent neurochemical and molecular pharmacological studies have indicated the existence of NMDA receptor subtypes which display differential modulation by glycine. In the present study, three potential modes of NMDA antagonism were differentiated in vitro by effects on [3H]-glycine binding to striatal sections. Specific [3H]-glycine binding was totally displaced by the glycine partial agonist (R)-HA-966; the NMDA-site antagonistd-CPP had no effect; and the NMDA-site antagonistd-AP5 displaced [3H]-glycine binding in a subpopulation of glycine sites. The anti-parkinsonian effects of (R)-HA-966,d-CPP andd-AP5 were assessed by intra-striatal injection in reserpine-treated rats and 6-OHDA-lesioned rats. Injection of (R)-HA-966 andd-CPP resulted in alleviation of parkinsonian akinesia, although the latter elicited anaesthetic-like side effects;d-AP5 was ineffective as an anti-parkinsonian agent. (R)-HA-966 was also effective as an anti-parkinsonian agent when administered systemically in the reserpine-treated rat. These data suggest that different classes of NMDA antagonist mediate different behavioural responses within the parkinsonian striatum. The behavioural response produced may depend on the exact nature of the conformational change induced by the antagonist and the location of the subtype most sensitive to that class of compound. Selection of a specific mode of NMDA receptor antagonism or targeting of striatal NMDA receptor subtypes may form the basis of a novel therapeutic approach to Parkinsons disease.

King's Parkinson's disease pain scale, the first scale for pain in PD: An international validation.

Pain is a key unmet need and a major aspect of non‐motor symptoms of Parkinsons disease (PD). No specific validated scales exist to identify and grade the various types of pain in PD. We report an international, cross‐sectional, open, multicenter, one‐point‐in‐time evaluation with retest study of the first PD‐specific pain scale, the Kings PD Pain Scale. Its seven domains include 14 items, each item scored by severity (0‐3) multiplied by frequency (0‐4), resulting in a subscore of 0 to 12, with a total possible score range from 0 to 168. One hundred seventy‐eight PD patients with otherwise unexplained pain (age [mean ± SD], 64.38 ± 11.38 y [range, 29‐85]; 62.92% male; duration of disease, 5.40 ± 4.93 y) and 83 nonspousal non‐PD controls, matched by age (64.25 ± 11.10 y) and sex (61.45% males) were studied. No missing data were noted, and floor effect was observed in all domains. The difference between mean and median Kings PD Pain Scale total score was less than 10% of the maximum observed value. Skewness was marginally high (1.48 for patients). Factor analysis showed four factors in the Kings PD Pain Scale, explaining 57% of the variance (Kaiser‐Mayer‐Olkin, 0.73; sphericity test). Cronbachs alpha was 0.78, item‐total correlation mean value 0.40, and item homogeneity 0.22. Correlation coefficients of the Kings PD Pain Scale domains and total score with other pain measures were high. Correlation with the Scale for Outcomes in PD‐Motor, Non‐Motor Symptoms Scale total score, and quality of life measures was high. The Kings PD Pain Scale seems to be a reliable and valid scale for grade rating of various types of pain in PD.

Δ9‐tetrahydrocannabinol (Δ9‐THC) exerts a direct neuroprotective effect in a human cell culture model of Parkinson's disease

C. B. Carroll, M.‐L. Zeissler, C. O. Hanemann and J. P. Zajicek (2012) Neuropathology and Applied Neurobiology38, 535–547

Reversal of parkinsonian symptoms in primates by antagonism of excitatory amino acid transmission : Potential mechanisms of action

Parkinsonism is characterised by overactive glutamatergic transmission in the cortico-striatal and subthalamo-medial pallidal pathways. Local blockade of glutamatergic transmission in these pathways can alleviate parkinsonian symptoms. The effectiveness of the treatment, however, is often limited by the simultaneous appearance of unwanted side-effects. These side-effects, including ataxia and dissociative anaesthesia, are particularly problematic when N-methyl-D-aspartate (NMDA) antagonists are used. In an attempt to overcome these problems we have attempted to manipulate excitatory amino acid (EAA)-mediated neurotransmission indirectly by targeting the NMDA receptor associated modulatory sites. We review evidence which demonstrates that antagonists for both the NMDA associated glycine and polyamine sites can reverse parkinsonian symptoms when injected intra-cerebrally in both MPTP-treated and bilateral 6-OHDA lesioned marmosets without eliciting unwanted side-effects. We further review preliminary data which suggest that ifenprodil, a polyamine site antagonist, has striking anti-parkinsonian actions in the marmoset. Potential mechanisms of action underlying these effects are discussed in terms of NMDA receptor subtypes and the neuroanatomical locus of action. The anti-parkinsonian efficacy of intra-striatally administered EAA antagonists leads us to question the view of dopamine acting in the striatum as a simple neuromodulator.