33.: Uhthoff’s phenomenon in osmotic demyelination syndrome

Uhthoff’s phenomenon was first described in 1890. It is defined as the worsening of neurological deficits or the development of new deficits in patients diagnosed with multiple sclerosis (MS) in the setting of increased body temperature. Osmotic demyelination syndrome (ODS) is a neurological disease that results from damage to the myelin sheath of nerve cells within the pons. There are various clinical manifestations of ODS including dysarthria, dysphagia, paresis, behavioural disturbances and coma. We report a patient with temperature dependant exacerbation of dysarthria in ODS. This is the first reported case of Uhthoff’s phenomenon in a patient with ODS to our knowledge. Uhthoff’s phenomenon is most commonly seen in patients with MS. There are few cases in the literature that describe Uhthoff’s syndrome in patients without a diagnosis of MS. We describe a patient who experienced Uhthoff’s symptom in the setting of ODS. This is plausible as ODS is a demyelinating entity. The demyelinating lesions and loss of oligodendrocytes in the basis pontis in ODS perhaps predisposes to impaired nerve conduction in the setting of elevated temperature, similar to that seen in MS. Therefore, with increasing temperature, it is not unreasonable to expect transient deterioration in neurological deficits in ODS. This case is noteworthy because it is the first reported description of Uhthoff’s phenomenon in ODS.