Aims, purpose, or objectives:

1. To describe the clinical features along with treatment outcomes of a cohort of patients with a diagnosis of NMOSD after the latest revised criteria in 2015 by International Panel for Neuromyelitis Optica Diagnosis (IPND)
2. To described the long term outcomes of a cohort of patients with a diagnosis of NMOSD
3. To identify demographic, clinical and radiologic factors associated with long terms outcomes of NMOSD
4. To determine if patients who are diagnosed with the revised 2015 IPND criteria, in particular those who do not satisfy previous criteria, are ultimately diagnosed with conditions other than NMOSD.
5. To identify treatment effects and complications in this cohort of patients

The aims of this study are:

• To assess the prevalence of episodic hypothermia among multiple sclerosis (MS) patients evaluated at Mayo Clinic.

• To characterize clinical, radiographic, and laboratory features of patients with MS-related hypothermia.

The study is designed to quantitate McArdle's sign, an increase in measurable weakness with neck flexion described in patients with multiple sclerosis, and to determine whether it is or is not specific for multiple sclerosis.