Ossification of the posterior longitudinal ligament (OPLL) is a process of fibrosis, calcification, and ossification of the posterior longitudinal ligament of the spine, that may involve the spinal dura. Once considered a disorder unique to people of Asian heritage, it is now recognized as an uncommon disorder in a variety of patients with myelopathy. Causes
The causes of OPLL are unknown. However, genetic and environmental factors appear to play a role in pathogenesis. OPLL may also be associated with diffuse idiopathic skeletal hyperostosis

Diagnosis
Myeolography, including post-myelographic CT is likely the most effective imaging study an accurate diagnosis. Treatment
Surgical management options include extensive cervical laminectomy with or without an additional posterior arthrodesis, anterior decompression and arthrodesis, and posterior cervical laminoplasty. Treatment decisions can be made based on a grading systems devised by Hirabayashi et al., supplemented by the Nurick myelopathy classification system. Prognosis
Most patients suffer from only mild symptoms. Symptoms typically last approximately 13 months. Of patients without myelopathy at initial presentation, only 29% of them will develop myelopathy within 30 years. Epidemiology
The age range of patients with OPLL is from 32 to 81 years (mean = 53), with a male predominance. Prevalence is higher in those of Japanese or Asian ancestry (2-3.5%)  and rarer in other racial groups (0.16%). Schizophrenia patients in Japan may have as high as 20% incidence. References


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A poor prognosis was assumed to apply to these patients by most clinicians, and this poor prognosis was harmful to many patients. The poor prognosis for DSM-IV schizoaffective disorder was not based on patient outcomes research, but was caused by poorly defined criteria interacting with clinical tradition and belief; clinician enculturation with unscientific assumptions from the diagnosis history (discussed above), including the invalid Kraepelinian dichotomy; and by clinicians being unfamiliar with the scientific limitations of the diagnostic and classification system.The DSM-5 schizoaffective disorder workgroup analyzed all of the available research evidence on schizoaffective disorder, and concluded that "presenting symptoms of psychosis have little validity in determining diagnosis, prognosis, or treatment response." Given our understanding of overlapping genetics in bipolar disorders, schizoaffective disorder, and schizophrenia, as well as the overlap in treatments for these disorders; but given the lack of specificity of presenting symptoms for determining diagnosis, prognosis or treatment response in these psychotic illness syndromes, the limits of our knowledge are clearer: Presenting symptoms of psychosis describe only presenting symptoms to be treated, and not much more. Schizoaffective disorder was changed to a longitudinal or life course diagnosis in DSM-5 for this reason. Research
Little is known of the causes and mechanisms that lead to the development of schizoaffective disorder.