He was admitted to the special care baby unit at 2 days of age because of poor feeding. His mother informed us that at the time he was noted to be hypotonic and his legs appeared weak. [doi.org]

A 15-year-old patient who had spondylocostal dysostosis (SCD) developed an MH crisis during general anesthesia. [ncbi.nlm.nih.gov]

The outcome ranges from death in infancy to survival beyond age five years. The weakness in CCD is not typically progressive. Diagnosis/testing. [ncbi.nlm.nih.gov]

Masseter spasm and malignant hyperthermia: a retrospective review of a hospital-based pediatric otolaryngology practice. Int J Pediatr Otorhinolaryngol. 1992 Jan; 23 (1):45–50. [ PubMed ] [ Google Scholar ] King JO, Denborough MA. [ncbi.nlm.nih.gov]

Masseter spasm and malignant hyperthermia: a retrospective review of a hospital-based paediatric otolaryngology practice. Int J Pediatr Otorhinolaryngol 1992 ; 23 : 45 –50. King JO, Denborough MA. Malignant hyperpyrexia in Australia and New Zealand. [doi.org]

This review will focus on myotubular myopathy, centronuclear myopathy, central core disease, and congenital neuromuscular disease with uniform Type 1 fiber, myopathies that are subjects of our ongoing examinations. [ncbi.nlm.nih.gov]

The proband and his mother were subsequently shown to be susceptible to malignant hyperthermia by abnormal in vitro muscle contractures in the presence of halothane or caffeine. [ncbi.nlm.nih.gov]

Standardisation of the caffeine halothane muscle contracture test. Anaesth Analg 1989 ; 69 : 511 –15. Jurkatt-Rott K, McCarthy T, Lehmann-Horn F. Genetics and pathogenesis of malignant hyperthermia. Muscle Nerve 2000 ; 23 : 4 –17. MacLennon D. [doi.org]

At age 5, he developed lordosis, talipes, and planovalgus. His grandmother died of malignant hyperthermia during surgery. [ncbi.nlm.nih.gov]

He had a moderate lumbar lordosis with waddling gait and positive Gower’s sign. His deep tendon reflexes were present except for the ankle jerks which were absent. [doi.org]

On physical examination, she had a high-arched palate, nasal tone vocalization, a positive Gowers' sign, waddling gait, and decreased deep tendon reflexes. [ncbi.nlm.nih.gov]

He had a moderate lumbar lordosis with waddling gait and positive Gower’s sign. His deep tendon reflexes were present except for the ankle jerks which were absent. [doi.org]

[…] between plasma membrane dihydropyridine receptors (DHPRs, L-type Ca2 channels) and Ca2 release channels (ryanodine receptors, RyR1s) of the sarcoplasmic reticulum orchestrates a complex, bi-directional Ca2 signaling process that converts electrical impulses [ncbi.nlm.nih.gov]

On physical examination, she had a high-arched palate, nasal tone vocalization, a positive Gowers' sign, waddling gait, and decreased deep tendon reflexes. [ncbi.nlm.nih.gov]

He had a moderate lumbar lordosis with waddling gait and positive Gower’s sign. His deep tendon reflexes were present except for the ankle jerks which were absent. [doi.org]

Severe cases present as neonatal hypotonia and contractures Skeletal : Increased incidence of congenital dislocation of hips and scoliosis Malignant hyperthermia : increased susceptibility. [genetics4medics.com]

Monnier N, Laquerriere A, Marret S et al : First genomic rearrangement of the RYR1 gene associated with an atypical presentation of lethal neonatal hypotonia. Neuromuscul Disord 2009; 19 : 680–684. 22. [nature.com]

Diagnostic approach to neonatal hypotonia: retrospective study on 144 neonates. Eur J Pediatr. 2008 May. 167 (5):517-23. [Medline]. Birdi K, Prasad AN, Prasad C, Chodirker B, Chudley AE. [emedicine.com]

In a series of 250 infants with neonatal hypotonia described by Fardeau and Tome, muscle biopsy performed before age 2 months revealed that only 14% had a congenital myopathy. [emedicine.medscape.com]