Table 1

Conditions with acute-on-chronic compromise potentially presenting to ICU with no previous diagnosis

Motor neurone diseaseCombination of upper and lower motor neurone signs
Progressive worsening
No sensory findings
Bilateral tongue wasting, ‘split hand’—wasted first dorsal interosseus and abductor pollicis brevis
Acid maltase deficiency (adult Pompe’s disease)Paraspinal muscle wasting
Pelvic girdle weakness, particularly of hip flexion
EMG fibrillation and myotonic discharges in iliopsoas and thoracic paraspinal muscles
Diagnosis—send dried blood spot enzyme assay for α-glucosidase
Enzyme replacement therapy available
Myotonic dystrophy (DM1)Reduced respiratory drive
Weak respiratory muscles
Postoperative complications in 10% (respiratory depression or pneumonia) may require ICU admission
Frontal balding (most marked in men)
Temporalis muscle atrophy
Cataracts and ptosis
Weakness of facial and neck flexion muscles
Distal forearm wasting, weak hand grip and foot drop
Smooth muscle involvement
  • Colon (constipation, soiling)

  • Dysphagia

Thenar eminence percussion elicits an exaggerated contraction with delayed relaxation (myotonia)
Electromyography identifies myotonia
Mitochondrial myopathy
Genes potentially in either mitochondrial DNA (mtDNA) or nuclear DNA
  • In adult practice, two-thirds are in mtDNA: one-third in nuclear DNA

  • In children, two-thirds are in nuclear DNA: one-third in mtDNA

Ptosis, progressive external ophthalmoplegia, optic atrophy or pigmentary retinopathy, cataract
Sensorineural hearing loss
Endocrine—diabetes, exocrine pancreatic failure, primary and secondary gonadal failure
Low body mass index (‘thin, diabetic and deaf’ and often young)
Cardiac—heart block, cardiomyopathy
Gastrointestinal dysmotility
Multiple neck lipomatosis (MERRF)
Myoclonus and epilepsy, particularly occipital seizures in a young adult or epilepsia partialis continua
Neuropathy, ataxia
Psychiatric, developmental delay or cognitive decline
Hirsutism occasionally (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes)
Ventilatory muscle weakness and reduced respiratory drive—hypoventilation following sedation or infection
(see figure 12).
Beware propofol (and valproate) use
Myofibrillar myopathiesCommon histopathological pattern but has many genetic causes
Onset usually 25–45 years
Distal, proximal or scapuloperoneal
Potential facial and pharyngeal weakness
Cardiomyopathy and/or peripheral neuropathy
Potential intestinal pseudo-obstruction
Cataracts in αB crystalline-related myofibrillar myopathies
Serum creatine kinase normal or mildly elevated
Some congenital myopathies (always consider congenital myasthenia in these patients)Tall, with a thin face and high-arched palate
Pes cavus, hammer toes
Generalised weakness and atrophy
Serum creatine kinase<3 times upper limit
Some have prominent respiratory muscle weakness while still ambulant (eg, mutations in TPM3 or SEPN1).
Congenital myasthenia, can present in adults
Slow channel—weakness in cervical muscles and finger extensors; mild ophthalmoparesis. Repetitive compound muscle action potential on motor studies neurophysiologically
DOK7—long myopathic face, myasthenic snarl, often a wasted tongue, mild proximal limb weakness, ptosis but no ophthalmoplegia
RAPSYN—frequent admissions to ICU with respiratory failure following infection, high-arched palate and long ‘myopathic face’, little ophthalmoplegia but often a squint.
Mutation in the epsilon subunit of the acetylcholine receptor causes significant ophthalmoplegia—often stable, most common cause in UK
  • GABAA, gamma-aminobutyric acid-A; ICU, intensive care unit; MERRF, myoclonus epilepsy with ragged-red fibers; MOG, myelin oligodendrocyte glycoprotein; MRC, Medical Research Council.