Psychogenic movement disorders (PMD) are challenging to diagnose and to treat. Since the nineteenth century, PMDs were recognized and described in painstaking detail. In the modern neurology clinic, PMDs may comprise 2-25% of the patient population. Recognition of the various types of PMDs, differentiation from organic illness and an approach to PMDs are described in this article.

The concentrations of organochlorine (OC) compounds in the substantia nigra (SN) were compared in Parkinson's disease (PD) with concentrations in brain from cortical Lewy body dementia (CLBD), Alzheimer's disease (AD), and nondemented nonparkinsonian controls (CON). The levels of the gamma isomer of hexachlorocyclohexane (gammaHCH, lindane) were significantly higher in PD tissues (mean +/- SD: 0.56 +/- 0.434 microg/g lipid) than in the other three groups (CLBD 0.052 +/- 0.101 microg/g lipid; AD none detected; CON 0.125 +/- 0.195; all differences from PD significant at p < .05, Mann-Whitney U-test). Dieldrin (HEOD) was higher in PD brain than in AD or control brain, while 1,1'-(2,2-dichloroethenyl diene)-bis(4-chlorobenzene) (p,p-DDE) and total Aroclor-matched polychlorinated biphenyls (matched PCBs) were only higher in PD substantia nigra when these concentrations were compared with those of CLBD. These findings are not inconsistent with the hypothesis derived from epidemiological work and animal studies that organochlorine insecticides produce a direct toxic action on the dopaminergic tracts of the substantia nigra and may contribute to the development of PD in those rendered susceptible by virtue of cytochrome P-450 polymorphism, excessive exposure, or other factors.

The development of abnormal posturing of the neck or shoulder after local injury has been termed posttraumatic cervical dystonia (PTCD). Certain features seem to distinguish a unique subgroup of patients with this disorder from those with features more akin to typical idiopathic cervical dystonia, such as onset and maximum disability that occurs very quickly after injury, severe pain and a fixed abnormal posture. In an attempt to clarify the nature of this syndrome further, we evaluated 16 such patients (8 men, 8 women). Motor vehicle accident and work-related injuries were common precipitants, with posturing usually developing shortly after trauma, and little progression occurring after the first week. A characteristic, painful, fixed head tilt and shoulder elevation were present in all but one patient, who had a painless elevated shoulder and painful contralateral shoulder depression, as well as nondermatomal sensory loss in 14 patients. Additional abnormalities included dystonic posturing in a limb (2 patients) or jaw (1 patient), limb tremor (3 patients) and "give-way" limb weakness (8 patients). The tremor and the jaw dystonia demonstrated features suggestive of a psychogenic movement disorder, most commonly distractibility. Litigation or compensation was present in all 16 patients. Intravenous sodium amytal improved the posture, pain or both in 13 of 13 patients; in 7 of 13 the sensory deficit either markedly improved or normalized. General anesthesia demonstrated full range of motion in all 5 patients assessed. Psychological evaluations suggested that psychological conflict, stress, or both were being expressed via somatic channels in 11 of 12 tested patients. Our results suggest an important role of psychological factors in the etiology or maintenance of abnormal posture, pain and associated disability of these patients. The role of central factors triggered in psychologically vulnerable individuals after physical trauma is discussed. We propose that the disorder be referred to as "posttraumatic painful torticollis" rather than characterize it as a form of dystonia until further information on its pathogenesis is forthcoming.