weakness /wēk″nəs/ , a condition of being feeble, fragile, frail, or decrepit or lacking physical strength, energy, or vigor. Causes of weakness include muscle disuse and nerve injury. Partially denervated muscle shows some degree of weakness, whereas completely denervated muscle becomes flaccid. Concomitant with partial denervation is a patient’s complaint of rapid fatigue and diminished capacity to perform activities of daily living. Deep tendon reflexes are diminished or absent, and electromyographic readings are abnormal.
