Shockwave for Clinic Use

Postherpetic neuralgia (PHN) is a common type of neuralgia related to neuronal damage and can seriously affect the quality of life due to the pain and poor response to the currently available treatments. The main approaches to PHN management are medication and invasive interventional therapies. However, these methods have many adverse effects. Physicians have used non-invasive ESWT to treat the pain area of PHN. It was found that both fESWT and rESWT could reduce pain and produced effective outcomes with few side effects when PHN was treated by ESWT. For example, a clinical study has shown that when ESWT [rESWT: R15 probe (radius of 15 mm), 1–4 bar, 5,000–7,000 pulses, 10 Hz] was used to treat patients with PNH, ESWT reduced pain and improved life quality compared with conventional therapies. Another clinical study showed that the medium-energy ESWT with 6 sessions (fESWT, EFD of 0.09–0.16 mJ/mm2, frequency of 5 Hz, and 2,000 pulses) could reduce the numerical rating scale of PNH, suggesting that fESWT could alleviate the skin pain and itch.

Trigeminal neuralgia (TN) is a severe type of neuralgia that occurs in the distribution area of the facial trigeminal nerve. Persons with TN tend to experience a series of painful symptoms. Zhang et al. reported that a woman with primary TN was treated by ESWT two times a week for 3 years with 3,000–6,000 pulses at a frequency of 10 Hz with an air pressure of 1.4–1.5 bar and the treatment sites were centered on the anterior ear region (the projection area of the trigeminal ganglion surface) and the pain area of the upper and lower jaw. The patient's pain was relieved after the 8-week treatment and the patient's life quality was significantly improved after the 3-month treatment. This study showed that ESWT produced good treatment efficacy, demonstrating the potential and feasibility of applying ESWT to treat diseases involving human facial and peripheral nerves.

Current clinical studies of ESWT mainly focus on peripheral nervous system diseases and much fewer studies have been carried out to explore the use of ESWT to treat human central nervous system diseases because of the concern about potential injury of the brain and spinal cord by ESWT. However, one study has already shown that ESWT could be applied to the brain of patients with unresponsive wakefulness syndrome to improve consciousness. In that study, it was found that the skull absorbs most of the shock wave energy and only about 10% of the total energy actually reached the brain. It was reported that ESWT could be effective if the actual energy that reached brain tissues was in the range of 0.01–0.02 mJ/mm2 . Werner et al. also used fESWT to treat brain stem (0.1 mJ/mm2, 4,000 pulses, 6 Hz) three times a week over four weeks with a penetration depth of the focus of approximately 5.5 cm. They reported that ESWT could stimulate vigilance in patients with unresponsive wakefulness syndrome and suggested that the use of ESWT with a relatively low EFD may cause fewer side effects when ESWT is used to treat human brain diseases. Moreover, the animal studies discussed above have also demonstrated the feasibility as well as safety of ESWT when it was employed to treat central nervous system diseases. Nevertheless, when ESWT is applied to the human brain or spinal cord, the energy dose of ESWT is still a critical issue for physicians to consider and more studies are needed to examine the potential adverse effects of ESWT on human brain tissues and determine the optimal ESWT energy level to be used so that ESWT can be used effectively as well as safely to treat the diseases involving human brain tissues.

Carpal tunnel syndrome (CTS) is an entrapment neuropathy of the median nerve characterized by pain and paresthesia in median nerve innervated areas. There are many conservative interventions such as therapeutic ultrasound, wrist splinting, and steroid injections to treat CTS, which reduce the intracarpal tunnel pressure by reducing inflammation reactions. However, these treatment approaches generally produce short-term therapeutic efficacy. Recently, ESWT was shown to be a promising therapeutic method for the treatment of peripheral nerve injury because of its therapeutic efficacy. They found that ESWT was a promising therapeutic strategy for patients with mild to moderate CTS and multiple-session ESWT produced cumulative clinical results. Other studies have shown that ESWT improved pain symptoms in patients with CTS and reduced the sensory latency of the median nerve.
ESWT can also potentially be an alternative conservative strategy. Compared with other conservative strategies, ESWT demonstrated good short-term treatment efficacy and produced long-term therapeutic effects on CTS. It was reported that the optimal therapeutic result can be achieved if the probe of ESWT is placed perpendicularly on the median nerve and the EFD level is low or medium when CTD is treated by ESWT. In general, both fESWT and rESWT can provide safe and good outcomes when used to treat CTS.