The impact of permanent muscle weakness on quality of life in periodic paralysis: a survey of 66 patients

Abstract

The periodic paralyses are hereditary muscle diseases which cause both episodic and permanent weakness. Permanent weakness may include both reversible and fixed components, the latter caused by fibrosis and fatty replacement. To determine the degree of handicap and impact of permanent weakness on daily life, we conducted a 68-question online survey of 66 patients over 41 years (mean age, 60 ± 14 years). Permanent weakness occurred in 68%, muscle pain in 82% and muscle fatigue in 89%. Eighty-three percent of patients reported themselves as moderately to very active between ages 18-35. At the time of the survey only 14% reported themselves as moderately to very active. Contrary to the literature, only 21% of patients reported decreased frequency of episodic weakness with increased age. Sixty-seven percent had incurred injuries due to falls. Mobility aids were required by 49%. Strength increased in 49% of patients receiving professional physiotherapy and in 62% performing self-managed exercise routines. A decline of strength was observed by 40% with professional and by 16% with self-managed exercise routine, suggesting that overworking muscles may not be beneficial. There is an average of 26 years between age at onset and age at diagnosis indicating that diagnostic schemes can be improved. In summary our data suggests that permanent muscle weakness has a greater impact on the quality of life of patients than previously anticipated.

Keywords: myopathy; paramyotonia congenita; periodic paralysis.

Figure 1.

Age at onset of symptoms and age at diagnosis. The percentage of the 66 patients with age of onset (blue) and age of diagnosis (red) in each of the age groups (0-10, 11-20, 21-30, 31-40, 41-50, 51-60, 61-82 years) is given. The yellow bar shows that the percentage of patients with onset at younger than 2 years makes up a fair portion of the age at onset group in the range of 0-10 years. Note the bi-modal distribution of the age at diagnosis and the latency between onset and diagnosis.

Figure 2.

Distribution of permanent muscle weakness. For the subgroup of patients with permanent weakness (45 individuals), the percentage of patients with weakness in each muscle group is given. Note the frequency of weakness of the quadriceps muscle and hip girdle.

Figure 3.

Benefit of professional physiotherapy versus self-managed exercise. Benefit from professional physiotherapy (in 38 patients) and self-managed exercise routines (55 patients). Note the large portion that deteriorated under profession physiotherapy. In contrast, note the large portion that benefited to different extents from the self-managed exercise.