Occipital Nerve Stimulation for Chronic Refractory Migraine

Chronic migraine remains disabling for a significant proportion of the population and challenging for medical providers. In addition to pharmacological treatment, peripheral nerve stimulation has been shown to provide satisfactory pain relief and improved quality of life. In this chapter, an illustrative case of occipital nerve stimulation (ONS) for refractory chronic migraine is presented, including the preoperative assessment and planning, decision making process, detailed surgical technique, aftercare and follow-up. A complication and its management are also described and discussed in detail and supplemented with clinical pearls. This discussion is accompanied by a review of the relevant evidence and outcomes from the literature.

Pelvic/Visceral Cancer Pain

The management of medically refractory cancer pain is a complex, multi-disciplinary effort. When optimal medical management has failed, neuroablative and neuromodulatory efforts can be used. While neuromodulation is an attractive option due its minimally invasive nature, neuroablation offers the advantage of high efficacy and the lack of maintenance or upkeep requirements. Punctate midline myelotomy is an ablative procedure targeting the ascending visceral pain pathway in the dorsal columns. The procedure can be performed through an open approach creating a mechanical lesion, or percutaneously via either a mechanical lesion or radiofrequency ablation. Careful attention to the spinal cord midline during lesion creation and attention to surgical technique, including an excellent fascial closure, can minimize potential complications.

Glossopharyngeal Neuralgia

Glossopharyngeal neuralgia is an uncommon, but devastating pain condition. It shares many features with trigeminal neuralgia, but predominantly affects the posterior tongue and pharynx. Since glossopharyngeal neuralgia pain is frequently triggered by swallowing or movement of the tongue, patients frequently present with weight loss and dehydration. This chapter describes the classic features of this condition, including its association with syncope. The medical management of glossopharyngeal neuralgia is outlined as a primary treatment modality. Surgical considerations are also described, including microvascular decompression or sectioning of the glossopharyngeal nerve. Surgical pearls for both of these procedures are outlined, as well as strategies for complication avoidance and management.

Intrathecal Drug Therapy for Painful Vertebral Metastases

Vertebral metastases often lead to a complex pain syndrome that consists of both nociceptive and neuropathic pain. Multimodal medical management often includes paracetamol, non-steroidal anti-inflammatory agents, bisphosphonates, opioids, antidepressants, anti-epileptics, and neuroleptics. Surgical treatment to address oncologic burden and spinal instability, radiation therapy, and vertebroplasty or kyphoplasty may be indicated for some patients. However, often times patients with advanced malignancies are not able to safely undergo surgery and have medication-refractory oncologic pain. For these patients and for patients unwilling to undergo large oncologic or spinal stabilization surgeries, intrathecal drug therapy (IDT) serves as a safe and effective adjunct in the management of cancer-related pain.

Dorsal Root Entry Zone Lesioning for Brachial Plexus Avulsion Pain

Brachial plexus avulsion is often seen after motorcycle accidents or with high-speed ejection injuries. Rehabilitation focuses on regaining motor and sensory function, but the detrimental effect of pain is often underappreciated. Up to 90% of patients with avulsion injury will experience deafferentation pain, which until relatively recently has been difficult to treat medically or surgically. DREZotomy, the ablation of neurons in the dorsal root entry zone of the spinal cord, was introduced in the 1970s and has since changed how we treat brachial plexus avulsion and other forms of neuropathic pain. The procedure is straightforward: with a standard cervical approach, a hemilamiotomy is used to expose the area of interest. The dura is opened, and areas of root avulsion are identified. Using bipolar cautery, RF ablation, or ultrasound, the 2nd order neurons in dorsal horn are destroyed for the affected dermatomes. Complications include standard cervical spinal approach-related issues, such as infection, hematoma, CSF leak, and kyphosis. Risks specific to the procedure include post-operative motor or sensory deficits, due to the proximity of the corticospinal tracts and the dorsal columns to dorsal horn. As many as 18% of patients report a long-term neurological deficit post-operatively, but despite these complications, 80% of patients say they would repeat the procedure. Multiple outcomes series have been published since the procedure was introduced, and typically 70–80% of patients receive benefit from the procedure.

Postherpetic Neuralgia

Postherpetic neuralgia (PHN) after acute herpes zoster ophthalmicus involves unilateral pain persisting or recurring for at least 3 months in the distribution of one or more branches of the trigeminal nerve. Patients often describe the pain associated with PHN as a deep aching or burning, dysesthetic, hyperesthetic, or electric shock-like sensation. The incidence of PHN increases with age and varies from 7 to 27%, depending on age group. 1 A subset of these patients develops medication-refractory PHN and should be referred for neurosurgical evaluation. Motor cortex stimulation (MCS) and trigeminal nucleus caudalis dorsal root entry zone (NC DREZ) lesioning are two therapies that may provide substantial relief to patients suffering from medication-refractory, postherpetic neuropathic facial pain.

Secondary Trigeminal Neuralgia (Balloon Compression Rhizolysis)

Multiple sclerosis is a common secondary cause of trigeminal neuropathic pain. It occurs because of the presence of sclerotic plaque within the highly myelinated trigeminal pathway. Patients with multiple sclerosis (MS) may also have a vascular compressive etiology; however, the two-year success rate for microvascular decompression is merely 15%. Ablative treatment also has a high pain recurrence rate that is as high as 50% in one year regardless of the surgical option selected. Balloon compression rhizotomy is a simple treatment option in MS patients. When done, the balloon compression site is at the retrogasserian portion of the trigeminal nerve and not the trigeminal ganglion. Balloon compression is associated with a trigeminal depressor response for which one must be prepared to treat with iv atropine.

Postherpetic Neuralgia of the Trigeminal Nerve (Trigeminal Tractotomy-Nucleotomy)

Trigeminal tractotomy-nucleotomy (TR-NC) is an effective operation in conditions where peripheral ablation would not be effective or when pain is due to involvement of multiple cranial nerves. Lesioning of the entire nucleus caudalis at the dorsal root entry zone (DREZ) represents a more extensive version of TR-NC. Here the focus is on the less invasive, percutaneous TR-NC or “mini-caudalis DREZ”. The target of TR-NC is the lateral descending trigeminal tract and nucleus caudalis of the spinal trigeminal nucleus. In select patient populations, careful lesion creation can be highly effective in providing immediate and long-lasting pain relief, with minimal adverse effects, lower cost and shorter hospital stays.

Painful Diabetic Neuropathy

Diabetic neuropathy may cause numbness and burning pain in a distal, symmetric distribution, typically involving the hands and feet. Management is with improved glucose control and treatment with tricyclic antidepressants, serotonin and norepinephrine reuptake inhibitors, and anti-epileptics. Surgical treatment is reserved for those patients with severe symptoms, with significantly impaired quality of life, for whom medications have not provided significant relief. There is evidence that spinal cord stimulation can provide a significant reduction in pain. A temporary trial of stimulation should be performed prior to permanent implantation. Leads may be placed in the epidural space percutaneously or via laminectomy and are connected to an internal pulse generator. Complications are typically device related. Treatment of device infection may require device removal.

Geniculate Neuralgia

Geniculate neuralgia is a rare syndrome of episodic, lancinating pain located within the ear canal. There may be a trigger point within the canal and associated with disorders of tearing, taste, and salivation. It is important to distinguish geniculate neuralgia from other causes of inner ear pain, including structural lesions and glossopharyngeal or trigeminal neuralgia. MRI may show vascular conflict with CN VII/VIII complex. Typical treatment is with carbamazepine. Surgery is reserved for those patients who have an incomplete response to medication. Surgery is directed at microvascular decompression of the CN VII/VIII complex with or without sectioning of the nervus intermedius. The entry zones of CN IX and X may also be explored. Complications and management are discussed.