Overview

Multi-minicore Disease (MmD) is a recessively inherited myopathy characterized by multiple cores on muscle biopsy and clinical features of a congenital myopathy.

There is often severe axial involvement, as well as respiratory, bulbar, and extra-ocular dysfunction.

Pathophysiology

Multiminicore disease is genetically heterogeneous

It is characterised by cores lacking oxidative enzyme activity. Four subtypes exist

1. The classical form, which is the most prevalent, consists of axial muscle weakness, commonly leading to severe scoliosis.

2. The moderate form with hand involvement, consists of generalized muscle weakness affecting predominantly the pelvic girdle but also includes amyotrophy and hyperlaxity: in this form scoliosis is mild or absent.

3. A form that is similar to classical MmD but also includes ophthalmoplegia.

4. Antenatal onset MmD with arthrogryposis (multiple joint contractures).

Impacts on anaesthesia

Risk of malignant hyperthermia

Expert opinion "There are no reports of patients with multiminicore disease developing clinical MH during general anaesthesia... So, although there is no definitive evidence to absolutely contraindicate volatile anaesthetics in MMD, we would currently advise caution in patients with MMD with a RYR1 etiology." [Klingler et al, 2009].

Expert opinion A family with malignant hyperthermia susceptibility was extensively investigated and found to have a high incidence of multiminicore lesions with neither clinical signs related to multiminicore disease nor histological features of congenital myopathies. The link between these two conditions is not yet clear. [Guis et al, 2004]