Effects of persistent Mal de debarquement syndrome on balance, psychological traits, and motor cortex exctiability.

Mal de debarquement syndrome (MdDS) is a poorly characterized and understood disorder of perceived motion. We sought to characterize postural control and the psychological impact of MdDS. Additionally, we explored whether patients with MdDS exhibit altered corticospinal and intracortical excitability. In a case-control study we compared patients with MdDS to age- and sex-matched controls (n=8/group). Postural stability (σr) was quantified from plane phase plots based on center or pressure, and psychological indices of depression, fatigue and kinesiophobia were obtained. Transcranial magnetic stimulation (TMS) was used to assess corticospinal excitability by quantifying the motor evoked potential (MEP) amplitude of the flexor carpi radialis, and intracortical excitability was assessed by quantifying indices of intracortical facilitation (ICF), and short-interval and long-interval intracortical inhibition using a paired-pulse TMS paradigm. The patients with MdDS exhibited greater mean (±standard error of the mean) σr during semi-tandem stance (10.9 ± 1.5 compared to 7.1 ± 0.7, p=0.04), higher levels of kinesiophobia (41.6 ± 2.8 compared to 27.3 ± 2.2), and higher levels of fatigue (27.0 ± 4.1 compared to 48.4 ± 1.0). Patients with MdDS exhibited a higher mean motor threshold (MT) (58.1 ± 2.5 compared to 47.4 ± 2.7% of stimulator output), and larger MEP (13.1 ± 3.1 compared to 5.1 ± 1.2% of maximal compound muscle action potential) but there was no difference in measures of intracortical excitability. These findings suggest that patients with MdDS exhibit impaired postural stability, and high levels of kinesiophobia and fatigue. Additionally, we observed that patients with MdDS exhibit higher MT and large MEP amplitudes, but do not exhibit differences in measures of intracortical excitability, compared to controls. These findings help characterize MdDS, and provide insight into the physiology of MdDS.

Social, societal, and economic burden of mal de debarquement syndrome.

Mal de debarquement syndrome (MdDS) is a disorder of phantom perception of self-motion of unknown cause. The purpose of this work was to describe the quality of life (QOL) of patients with MdDS and to estimate the economic costs associated with this disorder. A modified version of a QOL survey used for another neurological disease (multiple sclerosis; MSQOL-54) was used to assess the impact of MdDS on QOL in 101 patients. The estimated economic costs were based on self-reported direct and indirect costs of individuals living in the United States using Medicare reimbursement payment rates for 2011 in 79 patients. Patients with MdDS reported a poor overall QOL as indicated by a mean composite QOL score of 59.26 ± 1.89 (out of 100). The subcategories having the lowest QOL rating were role limitations due to physical problems (18.32 ± 3.20), energy (34.24 ± 1.47), and emotional problems (36.30 ± 4.00). The overall physical health composite score including balance was 49.40 ± 1.69, and the overall mental health composite score was 52.40 ± 1.83. The cost to obtain a diagnosis was $2,997 ± 337, which included requiring an average of 19 physician visits per patient. The direct cost of MdDS medical care was $826 ± 140 per patient per year, which mainly included diagnostic imaging and physician visits. The indirect costs (i.e., lost wages) were $9,781 ± 2,347 per patient per year. Among 65 patients who were gainfully employed when they acquired MdDS, the indirect costs were $11,888 ± 2,786 per patient per year. Thus, the total annual cost of the disorder ranged from $11,493 ± 2,341 to $13,561 ± 2,778 per patient per year depending on employment status prior to developing MdDS. MdDS negatively and dramatically impacts QOL, and also imposes a substantial economic burden on MdDS patients. These findings underscore the need for further basic and clinical research on MdDS.