Parkinson's disease (PD) is one of the most common neurodegenerative diseases. The last 5 years have been marked by rapid developments in understanding the pathophysiology of PD as well as by the introduction of a number of new drugs for symptomatic treatment of the disease. On the other hand, the diagnosis of PD is still made purely on clinical grounds. Due to continuing advances in therapy, it is increasingly important to recognize PD in its earliest stages and to distinguish it from other causes of parkinsonism, for which prognosis and response to treatment differ. This article reviews the epidemiology of PD and then elaborates on the diagnosis and differential diagnosis.

Parkinson's disease is the most common basal ganglia disorder that is caused by the degeneration of dopaminergic neurons in the substantia nigra. This article reviews the normal physiology of the basal ganglia in the normal state, as well as the pathophysiology of Parkinson's disease (PD) and other movement disorders associated with the basal ganglia. Also discussed is the pathophysiological basis for the surgical treatment of PD.

Recognizing the nonmotor symptoms associated with Parkinson's disease (PD) is necessary to determine effective treatment regimens and achieve patients' maximum mobility, as well as enhance their quality of life. The Unified Parkinson's Disease Rating Scale (UPDRS) is a useful tool for the clinician in evaluating the entire patient. In this article, the nonmotor disorders related to PD are reviewed, with specific attention to the first and last sections of the UPDRS, which cover mentation and complications of therapy, respectively. Various treatment regimens for these nonmotor symptoms are presented. Other autonomic nervous system symptoms associated with PD, which are not assessed in the UPDRS, are also discussed.

Impotence occurs in approximately one third of Parkinson's disease (PD) patients. It results from autonomic insufficiency, and is accompanied by other signs of autonomic insufficiency. Impotence may be aggravated by antiparkinsonian drugs and depression. Conversely, impotence may aggravate depression. In some patients, tremor, seborrhea, and drooling aggravate impotence by resulting in loss of self-esteem. The causes and treatment of impotence in PD are discussed in this article.

Catechol-O-methyltransferase (COMT) inhibitors are a new class of medication being developed for the treatment of Parkinson's disease (PD). The enzyme COMT metabolizes levodopa and dopamine, both peripherally and centrally. Coadministration of a COMT inhibitor with levodopa creates an increase in peripheral and central levodopa bioavailability, as well as higher central dopamine concentrations. Because these actions improve the duration of response to levodopa, the COMT inhibitors should prove to be useful adjunctive therapies in PD patients.

In an effort to aid the clinician in the differential diagnosis of catatonic states, we assessed the nature of electroencephalography (EEG) findings in both medical and psychiatric forms of catatonia. An exhaustive review of the literature on catatonia due to a general medical condition (CDGMC) was performed in addition to a prospective review of catatonic patients at The Ohio State University Neuwpsychiatric Facility.

A total of 105 patients had documented, specific clinical and EEG information, with neurologic conditions accounting for 82.8% of case reports. Results from the case series of 31 episodes of catatonia indicate that there is an increased likelihood of diffuse slowing in patients with CDGMC versus psychiatric catatonia. Given the observed rate of abnormalities, EEG is an important but underutilized tool in the differential diagnosis of catatonic disorders.

We present the case report of a patient who manifested seizures due to malingering, and discuss the differential diagnosis. The characteristics typical of nonepileptic seizures not due to malingering and of seizures due to malingering are described. Methods of distinguishing nonepileptic seizures from epileptic seizures are outlined, and the differences between seizures due to malingering and other nonepileptic seizures are discussed.