Multiple sclerosis is a degenerative disease prevalent in northern climates, and its cause is unknown. The histopathological lesion in multiple sclerosis is the sclerotic "plague", a discrete focus of myelin loss with maintenance of axon segments and glial proliferation. The plaques may be seen in widely different brain and spinal tissues. The common causes of low back pain are psychosomatic disorder, myofascial pain dysfunction syndrome and herniation of nucleus pulposus. Local anesthetics cross the blood-brain barrier and the signs of CNS toxicity appear at a level between 4.5 and 7.0 µg/ml. This is a case report of acute back pain care after mandibular block anesthesia for the surgical extraction of mandibular root rests in an old aged woman with multiple sclerosis.