Table 1. Differences between dropped head and bent spine syndrome.

	Dropped Head	Bent spine
Primary	Rare	Not infrequent
Muscles	Neck extensors	Erector spinae
Pathophysiology	Phasic > tonic	Phasic + tonic
Muscle CT Scan	Hypodensities	Myopathic
Coronal MR	?	Loss of paraspinal muscles
Muscle biopsy	Inflammatory, IBM	Rather myogenic
Onset	Subacute	Insidious
Outcome	Unchanged or Improved	No improvement
Handicap	Moderate	Stick or wheelchair
Secondary	Systemic and Multisystemic disease	NMD
Familial case	Exceptional	Some but no informative