Treatment-resistant chronic pain is a common medical problem. According to the German Pain Association (Deutsche Schmerzliga) approximately 8 million Germans suffer from chronic pain. It is often difficult to find the cause of the pain. Chronic pain, which is difficult to manage, can be associated e.g. with scar tissue formation after herniated disc surgery or trigeminal neuralgia (very intense pain in the area of the face supplied by the trigeminal nerve).
In order to optimize pain management we work closely with the Pain Centre of our hospital. In cases of unsuccessful conservative pain treatment or in patients who did not benefit from causal surgical treatment we offer the following further therapeutic procedures:
- Epidural spinal stimulation (spinal cord stimulation = SCS)
- Stimulation of peripheral nerves (peripheral nerve stimulation = PNS)
This method has been in use as a treatment option in chronic pain management since the 1970s, mostly in outpatient settings. It consists of 2 elements: neurostimulator and stimulating electrode. The stimulator generates mild electrical impulses that are delivered either to the neural pathways of the spinal cord (SCS) or directly to the affected nerves (PNS). Thus, a pleasant tingling sensation arises, which leads to relief of pain. The stimulating device is implanted under the skin, connected to the electrode by a special wire.
Fig 1: Images courtesy of Medtronic Company
Implantation is performed in 2 steps:
First, under local anaesthesia a microelectrode is implanted either in the direct vicinity of the spinal cord (on the spinal meninx, B) (SCS) or near the damaged (but still continuous) nerve. The position of the electrode is subsequently optimized to reach the full electrical stimulation coverage of the painful area. In the process the patient feels the aforementioned, pleasant “tingling” sensation.
Then, the neurostimulator is implanted, positioned under the rib cage. It is placed beneath the skin. The stimulator (A) is connected to the microelectrode via the connecting wire (A). The patient can subsequently turn the device on or off using a remote control. Additionally the strength of the impulse can be adjusted this way, to match it with the pain intensity felt by the patient.
Neurostimulation as a pain management procedure can be used in the following disorders:
- Peripheral artery occlusive disease (PAOD) (in cases of acute or chronic severe pain in the legs caused by narrowing of the arteries, resistant to conservative treatment options, in patients who cannot benefit from additional surgical or pharmacological treatment)
- Raynaud's Syndrome (painful narrowing of blood vessels of the fingers and toes)
Advantages of neurostimulation in selected patients, who responded favourably to test stimulation:
- Improvement as assessed by Fontaine stage
- Improvement of limb salvage rate
- Improvement of wound healing
- Relief of ischaemic pain
- Chronic pain in the legs after surgical treatment of herniated disc or spinal column ("failed back surgery syndrome", painful scars)
- Chronic pain of the arms and legs due to nerve damage (CRPS Type I-Morbus Sudeck, CRPS Type II)
- Chronic pain after limb amputation (phantom or stump painn)
- Chronic groin pain after multiple inguinal hernia surgery (post-herniorrhaphy pain syndrome)
- Chronic, usually one-sided burning pain of the chest after Herpes zoster viral infection of the nerves (post-zoster neuralgia)
- Chronic, usually left-sided dull or burning pain of the chest after surgery involving opening of the sternum (e.g. open-heart surgery) (Post sternotomy neuralgia)
- Chronic pain in the metatarsal area of the foot, caused by benign neuroma compressing the smallest nerve branches in the foot (treatment-resistant Morton's neuralgia)
- Sudden chest pain attacks caused by narrowing of the blood vessels in the heart not responding to conservative treatment, in patients who cannot benefit from additional surgical or pharmacological treatment.
Drug pumps enable continuous medication delivery in order to influence chronic pain or spasticity, e.g. in patients with trauma-caused paraplegia or multiple sclerosis.
The electronic pump (C) is surgically implanted under the skin (usually below the rib cage, on the left side). The pump sends small amounts of pain medication through the catheter (D) directly to the fluid surrounding the spinal cord (intrathecal).
Thanks to this method only a small fraction of the usual oral medication dose is used, thus significantly reducing side-effects of pharmacological treatment.
Fig 2. Images courtesy of Medtronic Company
Nowadays this procedure is rarely performed. It is applied mostly in cases of chronic, treatment-resistant pain in patients with nerve root damage, e.g. after motorcycle accidents (brachial plexus lesions) or in cancer patients.
It is performed under general anaesthesia. The transmission of pain signals from nerves to the spinal cord is cut off using electrical impulses which lead to local thermal coagulation in the area of the nerve entrance.
In this method computed tomography or X-ray visual control is used to deliver pain medication directly and with great precision to the nerve root, vertebral joint or intercostal nerve causing pain.
Discography is a diagnostic procedure allowing precise planning of the therapeutic approach. Radiographic contrast medium is injected into the intervertebral disc area using visual control (X-ray).