Although pain is not generally recognized as a symptom of tic disorders, we have seen a number of patients in whom this was a prominent feature, at times even the symptom of greatest concern. The commonest pain complaints are those arising from the actual performance of a tic. Most often this follows directly from the discomfort produced by sudden or repeated extreme exertion. Here the origin of the pain is usually musculoskeletal, though rare examples of neuropathic pain may occur. Pain also may arise from striking or being struck by a moving body part involved in large amplitude tics. Other related painful acts include deliberate self-injury and pain inflicted upon others. A second major category is represented by a smaller number of patients who complain of pain during voluntary efforts to suppress their tics. Finally, there are patients who obtain relief from tics while experiencing pain, to such an extent that they will deliberately provoke pain to obtain its benefit. We feel that pain should be recognized as a common complaint, and occasionally a source of significant disability, in patients with tics.

CQA 206-291, a new ergot derivative with a “biphasic” dopaminergic profile, was studied in 6 patients with longstanding Parkinson's disease suffering from pronounced fluctuations in hourly mobility. On alternate days, up to seven single doses, escalating from 0.2 to 20 mg, were given as replacement for the usual first morning dose of levodopa. At the most effective dosage, four of the six patients obtained as good a peak response to CQA (8-20 mg) as to L-dopa. Side effects were common and similar to other ergot derivatives, suggesting that the initial weak dopamine antagonist properties of the parent compound, documented in animals, may be of little clinical significance. However, comparative studies will be needed to confirm this suspicion. The addition of domperidone successfully reduced the incidence and severity of side effects. CQA 206-291 has potent anti-parkinsonian properties; further longer-term treatment trials are indicated.

The emergence of methyl-ammonium lead halide (MAPbX3) perovskites motivates the identification of unique properties giving rise to exceptional bulk transport properties, and identifying future materials with similar properties. Here, we propose that this “defect tolerance” emerges from fundamental electronic-structure properties, including the orbital character of the conduction and valence band extrema, the charge-carrier effective masses, and the static dielectric constant. We use MaterialsProject.org searches and detailed electronic-structure calculations to demonstrate these properties in other materials than MAPbX3. This framework of materials discovery may be applied more broadly, to accelerate discovery of new semiconductors based on emerging understanding of recent successes.