A Study of Quantitative Magnetic Resonance Imaging to Monitor Disease Activity in Hypokalaemic Periodic Paralysis (HypoPP).

Background

Hypo PP is the commonest muscle channelopathy. It is caused by mutations in the muscle sodium channels or calcium channels. From childhood, patients experience disabling episodes of complete muscle paralysis lasting hours to days.

In the early years patients recover between attacks. But over time they develop a permanent fixed muscle weakness (myopathy) and often become wheelchair bound. There are treatments which can reduce attack frequency.

But, we do not have sensitive methods to monitor disease activity or to determine if the treatment is fully effective.

Recent data show that the amount of water in the muscle may be important for muscle function. Patients with higher abnormal water content (oedema) have more weakness.

Preliminary published data show patients with less oedema may have a better prognosis. Furthermore, we currently make decisions to adjust standard treatments based on attack frequency only.

But, this may not be the best way to monitor actual disease activity in affected muscles.

Study information

Primary objective: to use MRI to assess abnormal muscle water content in Hypo PP patients.

MRI will be used in the context of the normal current clinical practice and management in this patient group.

This study has two phases. The first phase is a period of MRI technique refinement in up to 10 healthy volunteers lasting up to two months.

The main study phase is a longitudinal case control study. Assessments will be repeated at four weeks to see if any changes in clinical parameters are reflected in changes on MRI parameters.

Recruitment

At least 12 patients with HypoPP and 12 healthy volunteers as a comparison group for the patients.