Gamma Knife Central Lateral Thalamotomy for Chronic Neuropathic Pain: A Single-Center, Retrospective Study.

BACKGROUND: Chronic neuropathic pain can be severely disabling and is difficult to treat. The medial thalamus is believed to be involved in the processing of the affective-motivational dimension of pain, and lesioning of the medial thalamus has been used as a potential treatment for neuropathic pain. Within the medial thalamus, the central lateral nucleus has been considered as a target for stereotactic lesioning. OBJECTIVE: To study the safety and efficacy of central lateral thalamotomy using Gamma Knife radiosurgery (GKRS) for the treatment of neuropathic pain. METHODS: We retrospectively reviewed all patients with neuropathic pain who underwent central lateral thalamotomy using GKRS. We report on patient outcomes, including changes in pain scores using the Numeric Pain Rating Scale and Barrow Neurological Institute pain intensity score, and adverse events. RESULTS: Twenty-one patients underwent central lateral thalamotomy using GKRS between 2014 and 2021. Meaningful pain reduction occurred in 12 patients (57%) after a median period of 3 months and persisted in 7 patients (33%) at the last follow-up (the median follow-up was 28 months). Rates of pain reduction at 1, 2, 3, and 5 years were 48%, 48%, 19%, and 19%, respectively. Meaningful pain reduction occurred more frequently in patients with trigeminal deafferentation pain compared with all other patients (P = .009). No patient had treatment-related adverse events. CONCLUSION: Central lateral thalamotomy using GKRS is remarkably safe. Pain reduction after this procedure occurs in a subset of patients and is more frequent in those with trigeminal deafferentation pain; however, pain recurs frequently over time.

Gamma Knife radiosurgery for the treatment of cluster headache: a systematic review.

Cluster headache (CH) is a severe trigeminal autonomic cephalalgia that, when refractory to medical treatment, can be treated with Gamma Knife radiosurgery (GKRS). The outcomes of studies investigating GKRS for CH in the literature are inconsistent, and the ideal target and treatment parameters remain unclear. The aim of this systematic review is to evaluate the safety and the efficacy, both short and long term, of GKRS for the treatment of drug-resistant CH. A systematic review of the literature was performed to identify all clinical articles discussing GKRS for the treatment of CH. The literature review revealed 5 studies describing outcomes of GKRS for the treatment of CH for a total of 52 patients (48 included in the outcome analysis). The trigeminal nerve, the sphenopalatine ganglion, and a combination of both were treated in 34, 1, and 13 patients. The individual studies demonstrated initial meaningful pain reduction in 60-100% of patients, with an aggregate initial meaningful pain reduction in 37 patients (77%). This effect persisted in 20 patients (42%) at last follow-up. Trigeminal sensory disturbances were observed in 28 patients (58%) and deafferentation pain in 3 patients (6%). Information related to GKRS for CH are limited to few small open-label studies using heterogeneous operative techniques. In this setting, short-term pain reduction rates are high, whereas the long-term results are controversial. GKRS targeted on the trigeminal nerve or sphenopalatine ganglion is associated to a frequent risk of trigeminal disturbances and possibly deafferentation pain.

DREZotomy in the treatment of deafferentation pain: review of results and analysis of predictive factors for success. / Drezotomía en el tratamiento del dolor por desaferentización: revisión de resultados y análisis de factores predictores de éxito.

BACKGROUND AND OBJECTIVES: The treatment of deafferentation pain by spinal DREZotomy is a proven therapeutic option in the literature. In recent years, use of DREZotomy has been relegated to second place due to the emergence of neuromodulation therapies. The objectives of this study are to demonstrate that DREZotomy continues to be an effective and safe treatment and to analyse predictive factors for success. PATIENTS AND METHODS: A retrospective study was conducted of all patients treated in our department with spinal DREZotomy from 1998 to 2018. Bulbar DREZotomy procedures were excluded. A visual analogue scale (VAS) and the reduction of routine medication were used as outcome variables. Demographic, clinical and operative variables were analysed as predictive factors for success. RESULTS: A total of 27 patients (51.9% female) with a mean age of 53.7 years underwent DREZotomy. The main cause of pain was brachial plexus injury (BPI) (55.6%) followed by neoplasms (18.5%). The mean time of pain evolution was 8.4 years with a mean intensity of 8.7 according to the VAS, even though 63% of the patients had previously received neurostimulation therapy. Favourable outcome (≥50% pain reduction in the VAS) was observed in 77.8% of patients during the postoperative period and remained in 59.3% of patients after 22 months average follow-up (mean reduction of 4.9 points). This allowed for a reduction in routine analgesic treatment in 70.4% of them. DREZotomy in BPI-related pain presented a significantly higher success rate (93%) than the other pathologies (41.7%) (p=.001). No association was observed between outcome and age, gender, DREZ technique, duration of pain or previous neurostimulation therapies. There were six neurological complications, four post-operative transient neurological deficits and two permanent deficits. CONCLUSION: Dorsal root entry zone surgery is effective and safe for treating patients with deafferentation pain, especially after brachial plexus injury. It can be considered an alternative treatment after failed neurostimulation techniques for pain control. However, its indication should be considered as the first therapeutic option after medical therapy failure due to its good long-term results.

Complex regional pain syndrome type II arising from a gunshot wound (GSW) associated with infective endocarditis and aortic valve replacement.

A 34-year-old man with a history of gunshot wound (GSW) to the right upper chest developed secondary aortic valve endocarditis (AVE) and was treated with an artificial valve placement (AVP). Three months after, he presented to an outpatient pain management clinic right arm pain and was diagnosed with complex regional pain syndrome type II (CRPS II). The patient underwent a diagnostic sympathetic ganglion block, before undergoing endoscopic thoracic sympathectomy surgery. Successful outcomes revealed decreased pain, opioid utilisation and improved tolerance to therapy and activities of daily living. To our knowledge, this is the first case reporting CRPS II arising from a GSW complicated by AVE followed by AVP, which emphasises how unforeseen syndromes can arise from the management of seemingly unrelated pathology. This case demonstrates the importance of timely and proper diagnosis of uncharacterised residual pain status post-trauma and differential diagnosis and management of chronic pain syndromes.

Subarachnoid Block-Induced Deafferentation Pain Successfully Treated with Pentazocine.

Deafferentation pain induced by subarachnoid block (SAB) is rare, but it can appear in the form of recurrent phantom lower limb pain, new acute-onset stump pain in amputees, lower limb pain in patients with tabes dorsalis, and neuropathic pain. We have previously reported that thiopental is an effective treatment for deafferentation pain induced by therapeutic SAB applied to treat neuropathic pain of central origin. Here, we report the case of an amputee who developed new stump pain in his lower limb immediately after subarachnoid tetracaine was administered prior to appendectomy. A 51-year-old man who had previously undergone right below-knee amputation for acute arterial thrombosis, and who had not previously experienced chronic phantom limb or stump pain, was scheduled for emergency open appendectomy. For anesthesia, we induced SAB with a hyperbaric tetracaine solution. No paresthesia occurred during administration. However, the patient immediately complained of severe, lightning-bolt pain in the right lower limb stump after the SAB was established. He was given intravenous pentazocine, which promptly resolved the pain. Appendectomy was then performed under sedation using intravenous midazolam. The patient did not experience further deafferentation pain during his hospital stay and has reported no stump pain since discharge from the hospital. This case report suggests that SAB induces deafferentation pain in some patients and that this unusual pain can be treated with pentazocine.

LETM presented with causalgia and ensued by sudden death.

BACKGROUND: Longitudinally Extensive Transverse Myelitis LETM is a specific pattern of myelitis wherein at least three continuous vertebral segments are involved. Characteristically, it is a defining feature of neuromyelitis optica NMO. However, it is described in many other etiologies. CASE PRESENTATION: We present a case of 60 year old male who presented with symptoms and signs of regional sympathetic dystrophy RSD followed by symptoms of myelitis. Spinal cord MRI revealed cervical LETM extending to the brainstem. In spite of serological negativity, treatment of suspected neuromyelitis optica spectrum disorder NMOSD was initiated and resulted in symptom relief. Meanwhile, sudden death occurred and autonomic dysreflexia was the main culprit. CONCLUSIONS: This case suggests that RSD could be the mere primary presentation of LETM, discusses the differential diagnoses of LETM in elderly patients, and suggests the possible risk of autonomic dysreflexia in such patients.

Phantom pain in a patient with brachial plexus avulsion injury.

OBJECTIVE: Phantom limb pain is a painful sensation perceived in the absent limb following surgical or traumatic amputation. Phantom limb sensations, which are nonpainful, occur in nearly all amputees. Deafferentation can also produce similar symptoms. Here we report the presence of phantom pain in a deafferented limb. DESIGN: Case report. SETTING: Hospital-based outpatient clinic. PATIENT: A 65-year-old man was referred to the pain clinic for management of upper extremity pain secondary to brachial plexus avulsion (BPA) following a motor vehicle accident. Initially he noticed a feeling of growing and shrinking of his arm. Following this, the pain started gradually from his elbow extending to his fingertips covering all dermatomes. He described the pain as continuous, severe, and sharp. He also described the arm as being separate from his existing insensate arm and felt as though the fist was closed with the thumb pointing out. On physical examination, he had no sensation to fine touch or pressure below the elbow. There were no consistent areas of allodynia. He had diffuse muscle wasting in all the muscle groups of his left upper extremity, besides winging of the scapula. Electrodiagnostic studies showed a left brachial plexopathy consistent with multilevel nerve root avulsion sparing the dorsal rami. CONCLUSION: This is a report of phantom limb sensations and phantom pain following BPA in an intact but flaccid and insensate limb.

Intense pain soon after wrist fracture strongly predicts who will develop complex regional pain syndrome: prospective cohort study.

UNLABELLED: Complex regional pain syndrome (CRPS) is a distressing and difficult-to-treat complication of wrist fracture. Estimates of the incidence of CRPS after wrist fracture vary greatly. It is not currently possible to identify who will go on to develop CRPS after wrist fracture. In this prospective cohort study, a nearly consecutive sample of 1,549 patients presenting with wrist fracture to 1 of 3 hospital-based fracture clinics and managed nonsurgically was assessed within 1 week of fracture and followed up 4 months later. Established criteria were used to diagnose CRPS. The incidence of CRPS in the 4 months after wrist fracture was 3.8% (95% confidence interval = 2.9-4.8%). A prediction model based on 4 clinical assessments (pain, reaction time, dysynchiria, and swelling) discriminated well between patients who would and would not subsequently develop CRPS (c index .99). A simple assessment of pain intensity (0-10 numerical rating scale) provided nearly the same level of discrimination (c index .98). One in 26 patients develops CRPS within 4 months of nonsurgically managed wrist fracture. A pain score of ≥5 in the first week after fracture should be considered a "red flag" for CRPS. PERSPECTIVE: This study shows that excessive baseline pain in the week after wrist fracture greatly elevates the risk of developing CRPS. Clinicians can consider a rating of greater than 5/10 to the question "What is your average pain over the last 2 days?" to be a "red flag" for CRPS.

[Complex regional pain syndrome in a patient with acute drug poisoning: a case report].

We report a case with transition to complex regional pain syndrome (CRPS) caused by nerve injury associated with crush syndrome. The diagnosis was delayed because of coma due to acute drug poisoning. A 44-year-old man had attempted suicide by taking massive amounts of psychotropic drugs 2 days earlier and was transported to our hospital by ambulance. His arms had been compressed due to the prolonged (2 days) consciousness disturbance, and he experienced non-traumatic crush syndrome and rhabdomyolysis. Acute renal failure was prevented with massive infusion and hemofiltration. However, he experienced muscle and nerve injury at the compressed area, which presumably led to CRPS. In cases of suspected crush syndrome associated with acute drug poisoning, it is also important to recognize the possibility of developing CRPS.

Management of chronic pain following nerve injuries/CRPS type II.

Chronic pain affects quality of life and adversely affects functional outcomes. Chronic postoperative pain is a frustrating problem for the surgeon because it ruins a technically perfect procedure, and the surgeon may be unsure of treatment strategies. There is much information on chronic pain and its treatment, but it is often published outside of surgery and diffusion of this information across disciplines is slow. This article synthesizes some of this literature and provides a systematic presentation of the evidence on pain associated with peripheral nerve injury. It highlights the use of perioperative and early intervention to decrease this debilitating problem.

Atypical odontalgia: an up-to-date view.

Atypical odontalgia (AO) is a little known chronic pain condition. It usually presents as pain in a site where a tooth was endodontically treated or extracted, in the absence of clinical or radiographic evidence of tooth pathology. It is a rare clinical challenge for most clinicians, which leads to the patients being referred to several specialists and sometimes undergoing unnecessary surgical procedures. The pain mechanisms involved in AO are far from clear, and numerous potential mechanisms have been suggested. Currently, the most accredited hypothesis is that AO is a neuropathic pain condition caused by deafferentation. The differential diagnosis of AO remains difficult, because it shares symptoms with many others pathologies affecting this area. Patients have difficulties accepting the AO diagnosis and treatment. As a result, they frequently change physicians, and may potentially also receive several invasive treatments, usually resulting in an aggravation of the pain. Although some patients do get complete pain relief following treatment, for most patients the goal should be to achieve adequate pain management. Currently, most management is based on expert opinion and case reports. More research and high quality randomized controlled trials are needed in order to develop evidence-based treatments, currently based on expert opinion or carried over from other neuropathic pain conditions in the orofacial region.

Type II complex regional pain syndrome of the hand resulting from repeated arterial punctures during transradial coronary intervention.

Coronary catheterization using a transradial approach has become a common procedure, as the risks of local complications are low and this procedure affords relatively expeditious postprocedural patient mobilization. Access site complications--such as radial artery spasm, hematoma, and compartment syndrome--have been reported in the literature; however, cases of complex regional pain syndrome (CRPS) of the hand related to the procedure are extremely rare. We describe a case of type II CRPS affecting the hand after a transradial coronary intervention that was complicated by repeated periprocedural arterial punctures. In this case, a 55-year-old woman underwent a percutaneous coronary intervention for the treatment of unstable angina. After successful completion of the procedure, the patient complained of severe pain along the median and radial nerve distributions and resulting disability of the right hand. Although subsequent duplex sonography showed no abnormalities, a nerve conduction study uncovered injury to multiple nerves on the right. A diagnosis of type II CRPS was then made and the patient was treated with a nerve block as well as multiple medical modalities. This case demonstrates a very unusual complication resulting from the transradial approach to percutaneous coronary intervention.

A case of pain, motor impairment, and swelling of the arm after acute herpes zoster infection.

Complex regional pain syndrome (CRPS) and postherpetic neuralgia (PHN) represent neuropathic pain syndromes that may appear with similar clinical signs and symptoms. Medical history and clinical distribution of symptoms and signs (PHN typically at the thorax; CRPS typically at the limbs) is obvious in most cases, helping to discriminate between both disorders. Here, we present a patient suffering from CRPS II following PHN of one upper extremity. This case demonstrates that both etiology and part of the body affected by a neuropathy influence the pain phenotype.

Complex regional pain syndrome secondary to leprosy.

INTRODUCTION: Leprosy is a chronic infectious disease caused by Mycobacterium leprae affecting the skin and the nerves. Complex regional pain syndrome (CRPS/Sudeck's dystrophy) is a painful and disabling condition--a triad of autonomic, sensory, and motor symptoms disproportionate to the inciting event (inflammatory, infective, or traumatic nerve damage). CASE: A 20-year-old male presented with continuous pain, aggravated by cold and emotions, loss of fine touch and temperature sensation, redness, swelling, along lateral aspect of left hand and forearm with weakness in the grip of 6 months' duration. There was a 5-year history of sensory loss only over left index finger that he ignored. Examination revealed abnormal sensory and autonomic functions along left radial and median nerve distribution that were confirmed by nerve conduction studies suggestive of mononeuritis multiplex. Radial cutaneous nerve biopsy was suggestive of leprosy. Magnetic resonance imaging and ultrasonography showed no compressive etiology; however, MRI showed involvement of brachial plexus. Antileprosy, anti-inflammatory drugs, and steroids were given in view of neuritis because of lepra reaction with supportive measures of physiotherapy, transcutaneous electrical nerve stimulation, to no avail. A surgical median nerve decompression also failed to relieve the pain. Temporary stellate ganglion block improved the pain scale. Thus, excluding all other causes, the final diagnosis was CRPS secondary to leprosy. There is only one reported case of CRPS with leprosy. CONCLUSION: Leprous neuropathy caused the nerve damage that lead to CRPS type 2. Very rarely leprosy can lead to CRPS. CRPS is a diagnosis of exclusion.

Predilection to deafferentation pain syndrome after radiosurgery in cluster headache.

Cluster-tic syndrome is a rare, disabling disorder. We report the first case of cluster-tic syndrome with a successful response to stereotactic radiosurgery. After failing optimal medical treatment, a 58-year-old woman suffering from cluster-tic syndrome was treated with gamma knife radiosurgery. The trigeminal nerve and sphenopalatine ganglion were targeted with a maximum dose of 85 and 90 Gy respectively. The patient experienced a complete resolution of the initial pain, but developed, as previously described after radiosurgical treatment for cluster headache, a trigeminal nerve dysfunction. This suggests that trigeminal nerve sensitivity to radiosurgery can be extremely different depending on the underlying pathological condition, and that there is an abnormal sensitivity of the trigeminal nerve in cluster headache patients. We do not recommend trigeminal nerve radiosurgery for treatment of cluster headache.

Lower extremity complex regional pain syndrome type II after a craniotomy: case report.

Complex regional pain syndrome (CRPS) is a collection of signs and symptoms that most often include regional pain, edema, changes in skin temperature, increased skin sensitivity, and weakness that usually affects the extremities. It almost always exclusively affects the surgical site. A 52 year old woman presented with lower extremity CRPS due to positioning after a craniotomy.

Stimulation of the medial plantar nerve for complex regional pain syndrome.

We describe a 47-year old male with complex regional pain syndrome II in the distribution of the medial plantar nerve following metatarsal fracture, which was treated with peripheral nerve stimulation. Using a new technique of nerve stimulation with a percutaneous-type electrode, the patient experienced sustained relief at 12 months follow-up. To our knowledge, this is the first report of peripheral neurostimulation effectively managing pain for the medial plantar nerve.

The nerve of osteoarthritis pain.

OBJECTIVE: Cumulative data suggest that central sensitization may contribute to pain in osteoarthritis (OA) and present with symptoms typically associated with neuropathic pain (NP). We evaluated the responses from focus group participants on the knee OA pain experience for pain descriptions that suggest NP. METHODS: Focus group transcripts were analyzed by 2 independent assessors for unprompted use of pain descriptors that suggested NP. Items from validated NP symptom-based questionnaires were used to guide the analysis. Data on sociodemographic factors, duration of knee OA, and OA disease and pain severity (using the Western Ontario and McMaster Universities Osteoarthritis Index and a numerical rating scale) were obtained from questionnaires administered after focus group completion. These factors were compared among participants who did and did not use descriptors that suggested NP. RESULTS: Transcripts from 80 knee OA participants were analyzed. A range of NP descriptors was used to characterize their knee symptoms, including burning, tingling, numbness, and pins and needles. The proportion of participants who used NP descriptors was 0.34 (95% confidence interval 0.24-0.45). Those who used NP descriptors were younger (P = 0.003) and, although not statistically different, more likely to be women, with higher pain intensity and OA severity and longer OA duration, than those who did not use NP descriptors. CONCLUSION: During focus groups, a subset of adults with chronic, symptomatic knee OA used pain quality descriptors that were suggestive of NP. Elicitation of NP descriptors in people with OA may help identify those who could benefit from further evaluation and perhaps treatment for NP.