Cephalofacial pain is a large category of pain that is relatively common in clinical practice and is subdivided into headache and facial pain according to the specific scope and location of the pain, with trigeminal neuralgia, atypical facial pain, migraine, cluster headache, tension headache, occipital neuralgia and other pain types being the most common (Figure 1). The treatment of cephalofacial pain should be based on pharmacological treatment, especially at the early stage of the disease, and pharmacological treatment can generally achieve definite results. However, as the disease progresses and the pain becomes chronic, the effect of drug therapy will gradually diminish and the toxic side effects will become more and more obvious, and surgical treatment should be a treatment option at this time. Yongsheng Hu, Department of Functional Neurosurgery, Xuanwu Hospital, Capital Medical University
Figure 1 Pain sites of common headache types (Adapted from A.D.A.M. picture)
1. Principles of surgical treatment for cephalofacial pain
Surgical treatment of cephalofacial pain is mainly applicable to chronic cephalofacial pain and can be divided into three types of surgery: neuroanatomical surgery, neurodestructive surgery and neuromodulation surgery. For example, microvascular decompression (MVD) of cranial nerve roots is to separate the blood vessels compressing the cranial nerve roots from the nerve roots, and use special decompression materials to pad the blood vessels away from the nerve roots to release the compression of the blood vessels on the nerve roots, which is especially suitable for the treatment of It is especially suitable for the treatment of trigeminal neuralgia and glossopharyngeal neuralgia with vascular compression. Destructive surgery is the application of mechanical, physical or chemical methods to destroy the nerve, such as drug block, radiofrequency destruction, balloon compression, gamma knife irradiation, neurotomy and other procedures. As for modulating surgery, nerve electrical stimulation is used to modulate the nerve function to achieve pain control. The commonly used methods of nerve modulation include electrical nerve stimulation, repetitive transcranial magnetic stimulation, program-controlled drug pump intracerebroventricular or intrathecal injection, etc. According to the location of stimulation, electrical nerve stimulation can be divided into deep brain stimulation (DBS), motor cortex stimulation (MCS), spinal cord stimulation (SCS), and peripheral nerve stimulation (PNS). PNS).
In terms of the degree of impact on the affected nerve, anatomic and modulating procedures are minimally invasive or even non-invasive, while destructive procedures are invasive. Theoretically, the advantages of the former seem to be more obvious, and in practice, the efficacy of the former is more definite and long-lasting. However, the clinical selection of specific surgical procedures has to take into account the severity of the patient’s condition, physical condition, acceptance level and other factors, and make a comprehensive judgment and selection based on the principles of simple to complex operation, easy to difficult technique, and low to expensive cost.
Figure 2 Schematic diagram of the somatosensory distribution area of the head and face
2. Surgical treatment of common head and facial pain
2.1 Trigeminal neuralgia
It is the cephalofacial pain with the longest history of surgical treatment and the most satisfactory effect. Although drug block, radiofrequency destruction, balloon compression, gamma knife irradiation and neurotomy have been used to varying degrees in clinical treatment, the most satisfactory efficacy belongs to cranial nerve root MVD. Since the main and most common cause of trigeminal neuralgia is vascular compression of the trigeminal nerve root, only MVD is possible to cure trigeminal neuralgia in patients with vascular compression. Wang et al. summarized the results of 6010 cases of trigeminal neuralgia treated with MVD in the United States from 1988 to 2008, and the percentage of patients whose pain disappeared 10 years after surgery was 64%-74%. -74%, with an average recurrence rate of approximately 1% per year, concluding that MVD is the method of choice for the radical treatment of trigeminal neuralgia.
For patients with trigeminal neuralgia without clear vascular compression or recurrence after MVD, trigeminal hemimelia treatment with temperature-controlled radiofrequency disruption is a good option. Proper radiofrequency temperature control not only can effectively destroy the nociceptive nerve fibers while maximizing the function of the tactile nerve fibers, but also the application of intraoperative C-arm, CT, and neuronavigation can better improve the accuracy of percutaneous puncture of the semilunar ganglion. We have performed more than 200 cases of trigeminal nerve hemianoplasty with intraoperative neuronavigation technology and found that neuronavigation can provide real-time, visual, accurate, and radiation-free intraoperative guidance, and the one-time success rate of puncturing the foramen ovale can reach more than 80%. Combined with the application of intraoperative trigeminal nerve high-frequency sensory and low-frequency motor threshold tests, the accuracy of hemianoplasty radiofrequency disruption is greatly improved.
As for trigeminal nerve dissection, whether partial dissection of sensory roots or complete dissection of peripheral branches is done, the pros and cons should be weighed for careful selection, because the persistent facial numbness that occurs after nerve dissection is equally unbearable for many patients.
2.2 Central facial pain
The cause of central facial pain is in the central nervous system, and the pain site is in the face. Most of them are secondary to cerebral hemorrhage, cerebral infarction, traumatic brain injury, etc., and are often combined with pain in other parts of the body, or even in the hemiplegia. The treatment of central facial pain with analgesic drugs and nerve blocks is basically ineffective, and surgical treatment may be the only way to control or eliminate this pain. We use stereotactic intracerebral target disruption to disrupt the trigeminal thalamus on one side of the midbrain to block the somatosensory pathway of the contralateral head and face; at the same time, we combine the disruption of the anterior cingulate gyrus bilaterally to block the emotional response pathway of pain, which has a more definite and long-lasting analgesic effect than the disruption of one side of the midbrain or the anterior cingulate gyrus bilaterally. In addition, MCS can also achieve satisfactory results in the treatment of central facial pain, and this neuromodulation procedure is more internationally recognized and respected.
2.3 Atypical facial pain
In addition to pharmacological treatment, for atypical facial pain, it was once thought that stellate ganglion block or radiofrequency disruption on the affected side might be the most effective treatment. We have also tried to treat more than 50 patients with atypical facial pain with stellate nerve block and found that even with analgesic effect, most of them were only effective for a short period of 1-2 months. In comparison, the effect of SCS treatment in the high cervical segment (C2) is more durable and definite, and there are also reports that MCS can achieve satisfactory results as well.
2.3 Migraine
Stellate ganglion block has some efficacy in migraine, and we have also used this method to treat some cases, but it is generally difficult to obtain long-term stable analgesic effect. In recent years, the international literature on the surgical treatment of migraine has focused on the clinical application of Occipital nerve stimulation (ONS), which can significantly reduce the frequency, duration, and pain intensity of migraine attacks. We have performed three cases of ONS testing, all of which achieved more satisfactory results, but the patients did not eventually receive the implantation due to financial reasons. It seems that for the surgical treatment of migraine, it is not the technical aspects but the patient philosophy and economic aspects that have the greatest impact.
2.4 Cluster headache
Cluster headache is the most intense type of cephalalgia, and medication is at best only partially effective in relieving the pain, and most of the commonly used stellate nerve blocks and supraorbital nerve blocks are also poorly effective. In recent years, the real hope for the surgical treatment of cluster headache is neuromodulation procedures, including supraorbital nerve stimulation, ONS, subcutaneous area stimulation around the frontotemporal orbit, vagus nerve stimulation, etc., all of which have achieved exciting results.
2.5 Tension-type headache
Tension-type headaches are more diffuse and mostly involve the head bilaterally, and if treated with stellate ganglion block and occipital nerve block, they also need to be performed bilaterally separately in most cases. Likewise, nerve stimulation treatment is mostly performed bilaterally so as to obtain a more satisfactory treatment effect.
2.6 Occipital neuralgia
Occipital neuralgia is generally a general term for occipital major nerve, occipital minor nerve, inferior occipital nerve and 3rd occipital neuralgia, which also tend to exist together clinically. The most commonly used occipital nerve block is both a diagnostic and a therapeutic method that is easy to perform and easily repeatable. Although pulsed radiofrequency treatment of the occipital nerve can also yield good results, the ONS remains the one with the longest lasting analgesic effect.
3. Summary
For many chronic cephalofacial pains, surgical treatment is an important treatment method, for example, MVD can cure most of the trigeminal neuralgia with vascular compression; the most effective treatment for central facial pain is still surgery. In addition, a variety of neuromodulation procedures that have been gradually applied in recent years have not only achieved significant efficacy in migraine, atypical facial pain, cluster headache, occipital neuralgia and other cephalofacial pain, but also have the advantages of being less invasive and adjustable, representing the development trend of pain surgical treatment and providing a new method for the effective treatment of chronic cephalofacial pain.