Although uncommon, hypokalemia can be the reason for a puzzling quadriparesis associated with trauma. Sudden loss of muscle power usually can be traced to an injured spinal cord. Other conditions such as infections, tumors, and illnesses affect the neurological system and may do the same. V. M. Pruitt and J.D. Berne report the effects of a low level of potassium on the activity of skeletal muscle cells that contain adenosine triphosphate-sensitive potassium channels in high density (J Trauma. 2007; 62:epub ahead of print).
The authors describe a 48-year-old patient who fell from a chair on which she was standing. She struck her head on the floor and remained there for 7 hours. She was not unconscious, but fell asleep on the floor. When she woke, she was unable to walk. Her Glasgow Coma Scale score was normal (15). Computed tomography and magnetic resonance imaging showed no spinal cord or brain injuries. She had a major reduction in strength in her arms and legs. She reported having 7 days of diarrhea prior to her fall, and her serum potassium level dropped to 1.7 mEq/L (normal >3.5 mEq/L). Other abnormal serum electrolytes included low magnesium and phosphate.
Her deltoid, triceps, and biceps muscles had 3/5 strength, as did her quads and psoas muscles. However, grip and intrinsic muscle strength were normal as was lower limb distal muscle strength. While limb reflexes were diminished, rectal tone was normal.
Several conditions (eg, familial periodic paralysis and some renal diseases) result in muscle weakness associated with low potassium, but a gastrointestinal condition is most likely to be its cause when seen in an emergency department after a traumatic event.
|Blue Notes Editor:|
Charles Sorbie, MB, ChB, FRCS(E), FRCS(C)
Dr. Charles Sorbie is Professor of Surgery at Queens University and a member of the Attending Staff at the General and Hotel Dieu Hospitals in Kingston, Ontario.
A former chairman of the Department of Surgery at Queens University, Dr. Sorbie has been President of the Canadian Orthopaedic Research Society, the Canadian Orthopaedic Association, and the Societé Internationale de Chirurgie Orthopédique et de Traumatologie (SICOT).