Percutaneous Electrical Nerve Stimulation As Alternative To Nerve Blocks In Anesthesia, Pain Medicine And Rehabilitation Of Nonspecific Chronic Pain

Within the broad spectrum of chronic pain conditions, low back pain (LBP) is the leading cause of years lived with disability worldwide and one of the largest contributors to the global disease burden. According to the latest Global Burden of Disease analysis, approximately 620 million people suffered from LBP in 2020. Projections for the coming decades are not encouraging since, by 2050, the number of affected individuals is expected to rise to 843 million, a 36.4% increase compared to 2020. This growth will be mainly driven by population increase and aging, with the sharpest rises expected in Asia and Africa.

Beyond its direct health consequences, LBP imposes a considerable economic burden on both individuals and societies, as its highest incidence occurs during the most productive working years (approximately 45-55 years old). In the USA alone, direct costs related to spinal disorders reached USD 315 billion between 2012 and 2014, in addition to productivity losses estimated in hundreds of millions of workdays each year. Considering its growing prevalence and socioeconomic implications, LBP is regarded as a global health priority.

LBP may originate from a wide variety of musculoskeletal, neurological, or visceral conditions, and its clinical expression may combine nociceptive mechanisms (related to tissue injury or stimulation of lumbar structures), neuropathic mechanisms (involving lesions or disease of the somatosensory system), and nociplastic mechanisms (involving altered nociceptive processing without structural lesions, often with central sensitization and descending inhibitory dysfunction).

Current clinical frameworks establish that in up to 90% of patients, it is not possible to identify a clear anatomopathological pain source (thus defined as non-specific LBP). The main challenge lies in identifying which structures (i.e., intervertebral discs, facet /zygapophyseal joints, sacroiliac joints, ligaments, or myofascial tissues) are the nociceptive sources. The absence of a defined structural correlate (as most structural abnormalities are also frequent in asymptomatic individuals) largely explains the high recurrence and chronicity rates, as well as the frequency of ineffective treatments, unjustified surgeries, and the economic impact of healthcare utilization without a clearly established etiology. Consequently, diagnosis in these patients is essentially clinical and based on exclusion criteria, with a therapeutic focus on symptom modulation and functional recovery rather than on identifying and correcting a single structural lesion.

Although scientific evidence consistently supports the high percentage of non-specific LBP cases and discourage routine imaging in such patients, this practice remains common in hospital care. It is estimated that 30% to 55% of imaging studies requested for LBP are unnecessary or not clinically indicated. The indiscriminate use of imaging not only generates unnecessary costs and delays, but also exposes patients to unjustified radiation and overdiagnosis risk. For example, the prevalence of disc protrusions in asymptomatic individuals increases from 30% at age 20 to 84% at age 80, which may lead to misinterpreting benign degenerative changes as pathological, fueling overtreatment and patient anxiety.