Progress in neurological surgery最新文献

Successful management of facial pain starts with making correct diagnosis. Diagnostic errors, particularly early on in evaluation of facial pain patients are not uncommon, and some of this may be related to the lack of uniform classification that would satisfy needs of different specialists. Here, we critically review several most common classification schemes and try to compare and contrast their strength and unique features. We also attempt to link multiple terminologies describing same clinical conditions and provide a rationale for developing a unified nosological approach. Based on our findings, we conclude that despite many previous attempts, much work needs to be done to create a universally accepted, comprehensive but at the same time simple and user-friendly, facial pain classification, with the ultimate goal of integrating such classification into a treatment-guiding algorithm(s).

Motor cortex stimulation (MCS) has been used in the treatment of intractable neuropathic facial pain for nearly 30 years. While efficacy rates have been noted as high as 88% in some studies, considerable variability in treatment response remains. Additionally, MCS is often cited as providing diminishing relief over time, and there are few long-term studies on efficacy. Complications are generally mild and include infection, hardware complication, seizure, and transient neurological deficit. Despite relatively minimal use, MCS remains a viable treatment option for the appropriately selected facial pain patients that have proved refractory to conservative management.

The trigeminal nerve complex is a very important and somewhat unique component of the nervous system. It is responsible for the sensory signals that arise from the most part of the face, mouth, nose, meninges, and facial muscles, and also for the motor commands carried to the masticatory muscles. These signals travel through a very complex set of structures: dermal receptors, trigeminal branches, Gasserian ganglion, central nuclei, and thalamus, finally reaching the cerebral cortex. Other neural structures participate, directly or indirectly, in the transmission and modulation of the signals, especially the nociceptive ones; these include vagus nerve, sphenopalatine ganglion, occipital nerves, cervical spinal cord, periaqueductal gray matter, hypothalamus, and motor cortex. But not all stimuli transmitted through the trigeminal system are perceivable. There is a constant selection and modulation of the signals, with either suppression or potentiation of the impulses. As a result, either normal sensory perceptions are elicited or erratic painful sensations are created. Electrical neuromodulation refers to adjustable manipulation of the central or peripheral pain pathways using electrical current for the purpose of reversible modification of the function of the nociceptive system through the use of implantable devices. Here, we discuss not only the distal components, the nerve itself, but also the sensory receptors and the main central connections of the brain, paying attention to the possible neuromodulation targets.

Neuropathic facial pain is notoriously difficult to treat, regardless of its origin and duration. Since the first reported sphenopalatine ganglion blockade by Sluder in 1908, this ganglion has assumed an important role among the structures targeted for the treatment of facial pain. Recent years have witnessed the rise of neuromodulation over ablative procedures, including the development of an implantable stimulation device specially designed for use in the pterygopalatine fossa. Sphenopalatine ganglion stimulation has been demonstrated as effective and safe for refractory cluster headache, today the major indication for this therapy, but increasing evidence shows that the effect on the autonomic system and cerebral circulation could justify an even wider use of sphenopalatine ganglion stimulation for other chronic headache syndromes and vascular diseases.

Despite the high incidence of facial pain, targeted drug delivery remains a rarely used technique for treatment of otherwise refractory pain. Two distinct paths have been described. The intraventricular route allows direct access to intracerebral opioid receptors. The more recently introduced upper cervical or cisternal intrathecal route, is based on the same theories as classical intrathecal route. Intraventricular route was first described by A.K. Ommaya; its use remains limited, mostly with morphine, despite a high clinical efficiency, probably because of the invasive nature of the procedure and the need for daily direct injections. The ability to connect the catheter to an implantable pump may help to facilitate the acceptance of this approach. The also rarely used high cervical intrathecal or cisternal route is very efficient, because facial pain signals are transmitted mainly via the trigeminal nerve roots and synapse on the second-order neurons in an area that extends from the lower brainstem to the C1 and C2 levels of the spinal cord. The risks of cervical puncture may explain the rarity of its use. However, new devices allowing a simpler lumbar approach and the ongoing opioid crisis are the factors that may facilitate the wider use of this effective technique for the treatment of facial pain.

Facial pain occurs in approximately 80% of patients with head and neck cancers. Pain in these settings may result directly from the tumor, or indirectly as a side effect of oncological treatment of the tumor. Optimizing treatment for cancer pain of the face, therefore, involves a variety of diagnostic and treatment considerations, with the development of a successful treatment algorithm dependent on accurate diagnosis of the anatomical location of the pain, its relationship to the facial pain pathway, the type of pain being treated and, finally, patient's prognosis and preference for treatment modality. Beyond direct treatments to reduce tumor burden, a wide variety of neuro-ablative and neuro-augmentative approaches are available that may be tailored to a patient's specific pain syndrome and individual clinical context, taking into account the patient's treatment goals, life expectancy, other cancer-related medical problems, and end-of-life issues.

Since the first successful use of high-frequency electrical stimulation of trigeminal branches for treatment of facial pain in 1962, neuromodulation techniques become well established but remain greatly underutilised. Most subsequent implantation techniques and commercial devices for peripheral nerve stimulation, available until the last decade, utilised frequencies in the range 1-100 Hz. With the commercial introduction of 10-kHz spinal cord stimulation, there has been renewed interest in peripheral applications of kHz frequency neuromodulation. High-frequency biphasic stimulation causes rapid onset, reversible conduction block in mammalian nerves which might be useful in human peripheral neuromodulation applications, but the conduction block induced at kilohertz frequencies may not be the only mechanism contributing to analgesia. We discuss likely mechanisms of action of high-frequency peripheral nerve stimulation and present several clinical examples of successful use of this modality in various facial pain conditions. A change to sub-threshold higher frequencies in the 10 kHz range adds a number of distinct advantages. The lack of paresthesias is welcomed by patients. The ability to place the stimulating electrode approximately 1 cm away from the targeted nerve has an anatomical and surgical advantage.

Non-neuralgic trigeminal neuropathic pain can be challenging in terms of treatment as pharmacological interventions often tend to be ineffective. Within the pain-transmitting pathway, the Gasserian ganglion (GG) is a rather unique anatomical and physiological structure where the sensory (including pain) information from the entire half of the face undergoes primary processing in a very compact and clearly defined entity. Moreover, GG is positioned in a completely immobile intradural location (the Meckel's cave) and is insulated from the brain by a layer of dura. As a confluence of all three trigeminal branches, GG allows one to achieve clinical effect on the entire half of the face with a relatively small surgical intervention while maintaining an ability to select exact facial regions based on known somatotopic organization of nerve fibers. Therefore, when it comes to electrical neuromodulation, the GG stimulation (GGS) may be a unique solution for treatment of medically refractory facial pain. GGS was introduced in 1970s and continues to be a recognized surgical modality with multiple published clinical series describing multi-year experience in hundreds of facial pain patients. GGS is particularly useful in treatment of patients with chronic trigeminal neuropathic pain and persistent idiopathic facial pain who tried and failed or were not considered good candidates for the conventional surgical interventions. With advances in lead technology, intraoperative visualization and stereotactic navigation, percutaneous GGS became a minimally invasive surgical intervention that is recommended for consideration in complex facial pain. Here, we review the clinical data and summarize the current state of GGS in facial pain treatment.