Parkinson's Disease: Historical Aspects and Current Treatment Approaches

Parkinsonism

Parkinsonism is a syndrome manifested by a combination of six cardinal features. They are:

• Resting tremors.

• Increased tone of the muscles (aka rigidity).

• Slowness of movements (bradykinesia).

• Loss of postural reflexes.

• Bent or flexed posture.

• Freezing of gait (aka motor blocks).

James Parkinson in 1817 wrote '' An Essay on the Shaking Palsy'' in which he described 6 cases which had a combination of the aforementioned features. He had observed these individuals on the streets of London.

Charcot in the nineteenth century acknowledged Parkinson's contribution and referred to this condition as ''maladie de Parkinson''. A century after ''An Essay on the Shaking Palsy'' was written, loss of dopaminergic cells in the substantia nigra was identified as the pathological basis of this disease.

Non-motor Manifestations of Parkinson's Disease (PD)

• These include sleep disturbances and impaired gastrointestinal function.

• These occur in a staggering 88% of all patients, and are more troublesome than the classic features like tremors, slowness of movement and increased muscle tone.

• Approximately, 40-48% of these patients go on to develop dementia, which is called Parkinson's Disease Dementia, or PDD.

• Other non-motor features include excessive day-time sleepiness (narcolepsy and sleep attacks), falls, fractures, drop in blood pressure (postural hypotension), urinary incontinence, inability to articulate properly (aka dysarthria), visual and auditory hallucinations.

Neurobehavioral and Neuropsychiatric Manifestations of Parkinson's Disease

• These impair the quality of life of the individual and need a comprehensive clinical assessment by a psychiatrist, who can effectively diagnose and offer rationalized treatment solutions.

• These manifest as anxiety disorders, slowness of thinking, fatigue, a feeling of restlessness and inability to sit at one place (aka akathisia), fatigue, hearing of voices in isolation, and other psychotic features like delusions.

Management of the Illness

• Modern brain imaging techniques include MRI (functional magnetic resonance), DWI (diffusion weighted imaging) and DAT (dopamine transporter) imaging scans.

• However, like schizophrenia, parkinson's is a clinical diagnosis in the first place, and no amount of investigation can match the clinical expertise of a neuropsychiatrist or a neurophysician.

Medical and Surgical Treatments of Parkinson's Disease

• Encourage patients to remain active and mobile.

• Keep the patient functioning independently as long as possible.

• Individualize therapy as there is no one-size-fits-all treatment.

• Some commonly used drugs include Levodopa with Carbidopa or Benserazide, Bromocriptine, Entacapone, Selegiline, Tranylcypromine and Zonisamide.

• However, these agents come with their own side-effects like causing psychosis, hallucinations, impulse-control disorders, and fluctuations in their efficacy, a feature called ''on-off'' phenomenon.

• Surgical treatment - This is tried in treatment resistant Parkinson's Disease. The procedures include thalamotomy (removal of the thalamus), ablating a part of the brain called pallidum and subthalamic nucleus (present below the thalamus). However, these procedures have been replaced by what is called Deep Brain Stimulation, or DBS. The disadvantages of the surgical modality include invasiveness of the treatments, unclear long-term outcomes, and the economic burden on the patient.