Senile chorea.

The term "senile chorea" is applied to cases of sporadic chorea with onset after the age of 50 years. The causes of senile chorea are numerous and include drugs, medications, cerebrovascular disease, genetic and sporadic neurodegenerations, and a range of systemic (hematological, metabolic, immune) disorders. The cause of senile chorea can be determined after systematic investigation in most cases.

Reversible cerebral vasoconstriction, internal carotid artery dissection and renal artery stenosis.

Reversible cerebral vasoconstriction is a rare and poorly understood syndrome, without clear diagnostic criteria. It has been described in association with multiple disorders, but has only been reported rarely in the setting of carotid artery dissection and, to our knowledge, never before in association with renal artery stenosis.

Resolution of dopamine dysregulation syndrome following cessation of dopamine agonist therapy in Parkinson's disease.

Repetitive and compulsive behaviours can occur in association with the use of dopaminergic medications for the treatment of Parkinson's disease (PD). This syndrome has been referred to as the 'dopamine dysregulation syndrome'. The prognosis for patients with this syndrome is unclear. We report five PD patients in whom the abnormal behaviours resolved completely after withdrawal of dopamine agonist therapy. We alert clinicians to the apparent role of dopamine agonists in this syndrome. In addition, we highlight the potential reversibility of the syndrome, its varied phenomenology and its potential pathophysiology.

Ataxic arm movements after thalamotomy for Parkinsonian tremor.

Voluntary finger-nose movements of the arm were analysed in six patients undergoing stereotaxic nucleus ventralis intermedius thalamotomy for relief of severe Parkinsonian tremor. In all cases thalamotomy acutely abolished tremor in the contralateral arm. In the early postoperative phase, ataxia of the arm contralateral to the operated side was also seen. Ataxia was transient, lasting between 7 and 21 days postoperatively. This observation suggests that a lesion of the Vim nucleus interrupts cerebellar input to the thalamus, and supports the concept that abnormal cerebellar activity is an important contributor to the generation of tremor in Parkinson's disease.

Increased blink rate in advanced Parkinson's disease: a form of 'off'-period dystonia?

Blink rates were measured in 25 patients with fluctuating Parkinson's disease in the "off' and "on" periods. In 17 patients, the "off"-period blink rate was low and increased after administration of levodopa. In the remaining eight patients, the "off"-period blink rate was high and returned to normal levels after levodopa. It is suggested that increased blink rate in the latter group represents a new form of "off"-period dystonia.

The silent period after magnetic brain stimulation in generalized tetanus.

The cortical silent period has not previously been studied in tetanus. Transcranial magnetic brain stimulation in a patient with generalized tetanus revealed enlarged electromyographic (EMG) responses and absence or reduction of the late phase of EMG silence following the motor evoked potential in sternomastoid and biceps brachii muscles. Following clinical recovery, the silent period returned to normal. This observation is interpreted as evidence of impaired inhibitory mechanisms at multiple levels of the nervous system, including the cortex, in generalized tetanus.

Voluntary movement after pallidotomy in severe Parkinson's disease.

The mechanisms of improvement in parkinsonian bradykinesia after posteroventral pallidotomy were investigated in 17 patients undergoing unilateral pallidotomy for severe Parkinson's disease. Clinical ratings of 'off' period bradykinesia demonstrated a maximal improvement of 22% 3 months postoperatively. Kinematic assessments of rapid repetitive finger and sequential arm movements were performed after overnight withdrawal of antiparkinsonian medications. There was a bilateral reduction in the inter-onset latency of a two-stage sequential arm movement and a contralateral increase in speed of arm movement after pallidotomy. There was no significant improvement postoperatively in the rhythm, amplitude or speed of repetitive finger movements. The results confirm the clinical impression that pallidotomy improves bradykinesia. This was more evident for complex limb movements, which used attentional strategies and external (visual and auditory) cues, than for repetitive fingertapping movements, which were largely internally generated. Since ablation of the pallidum can only reduce inhibitory pallidal outflow, it is unlikely to restore the normal pallidal influence on thalamocortical motor circuits. Therefore, any improvement in bradykinesia after pallidotomy must be related to mechanisms other than restoration of pallidothalamocortical connectivity. Based on the above observations, we suggest that some of the changes in motor control may be explained by the greater efficacy of external cues in facilitating movement after withdrawal of the abnormal pallidal discharge.

Familial neuronal intranuclear inclusion disease with ubiquitin positive inclusions.

Female monozygotic twins developed upper and lower limb neurogenic weakness in their thirties, followed by cerebellar ataxia, dysarthria and death after an illness duration of about 20 years. Autopsy revealed pathological features typical of neuronal intranuclear inclusion disease (NIID) and positive ubiquitin immunostaining of the inclusions. Two adult sons of one of the twins have now developed an identical illness. This family provides strong evidence of an hereditary form of NIID.

Modulation of primary orthostatic tremor by magnetic stimulation over the motor cortex.

OBJECTIVES: To study the role of corticomotor neuronal pathways in primary orthostatic tremor. METHODS: Transcranial magnetic stimuli at an intensity 10% above the resting motor threshold were delivered over the leg motor cortex in two patients with primary orthostatic tremor while standing still. Electromyographic responses in both tibialis anterior muscles were recorded after 20 stimuli given randomly at intervals of 120 to 180 seconds. Differences between predicted and actual times of occurrence of tremor bursts after the stimuli were used to calculate a resetting index, with a value of 0 representing no resetting and a value of 1 representing complete resetting. RESULTS: Transcranial magnetic stimulation evoked EMG responses in both tibialis anterior muscles, followed by transient suppression of tremor before reappearance of rhythmic EMG activity. Analysis of the timing of tremor bursts from EMG recordings before and after the magnetic stimuli disclosed that the phase of orthostatic tremor could be reset by brain stimulation (mean resetting indices 0.93 and 0.82). CONCLUSION: The results suggest that a central oscillator, involving the motor cortex, has a crucial role in either the generation or modulation of orthostatic tremor.