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Logo of neurologyNeurologyAmerican Academy of Neurology
Neurology. 2010 April 20; 74(16): e69.
PMCID: PMC3462505

Teaching Video NeuroImages: The breathing arm

Respiratory brachial synkinesis

A 19-year-old man sustained a right upper trunk brachial plexopathy from a stab wound and became paralyzed in the right proximal arm. Twelve months later, he underwent microsurgical anastomosis of injured C5 and C6 nerve roots to the more distal C5 nerve root. At 14 months postoperatively, there were involuntary movements of his right biceps and deltoid muscles time-locked to inspiration (see video on the Neurology® Web site at; see figure).

figure 18ff1
Figure EMG recording of biceps and intercostal muscles

The diaphragm receives innervation from C3–C5 nerve roots via the phrenic nerve. During regeneration of motor neurons originally destined for the phrenic nerve, aberrant regrowth into the upper trunk of the brachial plexus resulted in reinnervation of the biceps brachii and deltoid (via musculocutaneous and axillary nerves), rather than the phrenic nerve. The result is involuntary contraction of the biceps and deltoid muscles time-locked to breathing or the “breathing arm” syndrome. This phenomenon has been observed after surgery or trauma, including obstetric brachial plexus injuries. Congenital variants also exist, including trigemino-abducens synkinesis.1–3

Supplementary Material


Supplemental data at

Disclosure: Dr. Lam reports no disclosures. Dr. Engstrom receives research support from the NIH (2 RO1 HL062235-06 [Co-I]).


1. Friedenberg SM, Hermann RC. The breathing hand: obstetric brachial plexopathy reinnervation from thoracic roots? J Neurol Neurosurg Psychiatry 2004;75:158–160. [PMC free article] [PubMed]
2. Swift T, Leshner R, Gross J. Arm diaphragm synkinesis: electrodiagnostic studies of aberrant regeneration of phrenic motor neurons. Neurology 1980;30:339–344. [PubMed]
3. Lai T, Chen C, Selva D. Bilateral congenital trigemino-abducens synkinesis. Arch Ophthalmol 2003;121:1796–1797. [PubMed]

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