Upper-limb neurovascular compression, pectoralis minor and quadrilateral space syndromes: A narrative review of current literature.

Pectoralis minor syndrome (PMS) and quadrilateral space syndrome (QSS) are uncommon neurovascular compression disorders affecting the upper extremity. PMS involves compression under the pectoralis minor muscle, and QSS results from compression in the quadrilateral space-both are classically observed in overhead-motion athletes. Diagnosing PMS and QSS may be challenging due to variable presentations and similarities with other, more common, upper-limb pathologies. Although there is no gold standard diagnostic, local analgesic muscle-block response in a patient with the appropriate clinical context is often all that is required for an accurate diagnosis after excluding more common etiologies. Treatment ranges from conservative physical therapy to decompressive surgery, which is reserved for refractory cases or severe, acute vascular presentations. Decompression generally yields favorable outcomes, with most patients experiencing significant relief and restored baseline function. In conclusion, PMS and QSS, although rare, can cause debilitating upper-extremity symptoms; accurate diagnosis and appropriate treatment offer excellent outcomes, alleviating pain and disability.

On the Physiology of the Sensory-Collapse Test.

The sensory-collapse test (formerly the scratch-collapse test) is a physical examination finding describing a momentary inhibition of external shoulder rotation following light stimulation of an injured nerve in the ipsilateral limb. Similar to other physical examination tests designed to interrogate nerve compression, such as the Phalen or Tinel tests, its test characteristics demonstrate variation. There remains speculation about the test's existence and anatomic basis. The literature of mammalian reflex physiology was reviewed with an emphasis on the sensory pathways from the upper extremity, the extrapyramidal system, and newly discovered pathways and concepts of nociception. A clear reflex pathway is described connecting the stimulus within an injured nerve through the afferent pathways in the fasciculus cuneatus in the spinal cord directly to the lateral reticulospinal tract, resulting in the inhibition of extensor muscles in the proximal limb (eg, shoulder) and activation of the limb flexors by acting upon alpha and gamma motor neurons. The sensory-collapse test represents a reflex pathway that teleologically provides a mechanism to protect an injured nerve by withdrawal toward the trunk and away from the noxious environment.

Extracellular ATP and cAMP signaling promote Piezo2-dependent mechanical allodynia after trigeminal nerve compression injury.

Trigeminal neuralgia (TN) is a type of severe paroxysmal neuropathic pain commonly triggered by mild mechanical stimulation in the orofacial area. Piezo2, a mechanically gated ion channel that mediates tactile allodynia in neuropathic pain, can be potentiated by a cyclic adenosine monophosphate (cAMP)-dependent signaling pathway that involves the exchange protein directly activated by cAMP 1 (Epac1). To study whether Piezo2-mediated mechanotransduction contributes to peripheral sensitization in a rat model of TN after trigeminal nerve compression injury, the expression of Piezo2 and activation of cAMP signal-related molecules in the trigeminal ganglion (TG) were detected. Changes in purinergic P2 receptors in the TG were also studied by RNA-seq. The expression of Piezo2, cAMP, and Epac1 in the TG of the TN animals increased after chronic compression of the trigeminal nerve root (CCT) for 21 days, but Piezo2 knockdown by shRNA in the TG attenuated orofacial mechanical allodynia. Purinergic P2 receptors P2X4, P2X7, P2Y1, and P2Y2 were significantly up-regulated after CCT injury. In vitro, Piezo2 expression in TG neurons was significantly increased by exogenous adenosine 5'-triphosphate (ATP) and Ca2+ ionophore ionomycin. ATP pre-treated TG neurons displayed elevated [Ca2+ ]i and faster increase in responding to blockage of Na+ /Ca2+ exchanger by KB-R7943. Furthermore, mechanical stimulation of cultured TG neurons led to sustained elevation in [Ca2+ ]i in ATP pre-treated TG neurons, which is much less in naïve TG neurons, or is significantly reduced by Piezo2 inhibitor GsMTx4. These results indicated a pivotal role of Piezo2 in peripheral mechanical allodynia in the rat CCT model. Extracellular ATP, Ca2+ influx, and the cAMP-to-Epac1 signaling pathway synergistically contribute to the pathogenesis and the persistence of mechanical allodynia.

Efficacy of 5% Dextrose Water Injection for Peripheral Entrapment Neuropathy: A Narrative Review.

Current non-surgical treatment for peripheral entrapment neuropathy is considered insignificant and unsustainable; thus, it is essential to find an alternative novel treatment. The technique of perineural injection therapy using 5% dextrose water has been progressively used to treat many peripheral entrapment neuropathies and has been proven to have outstanding effects in a few high-quality studies. Currently, the twentieth edition of Harrison's Principles of Internal Medicine textbook recommends this novel injection therapy as an alternative local treatment for carpal tunnel syndrome (CTS). Hence, this novel approach has become the mainstream method for treating CTS, and other studies have revealed its clinical benefit for other peripheral entrapment neuropathies. In this narrative review, we aimed to provide an insight into this treatment method and summarize the current studies on cases of peripheral entrapment neuropathy treated by this method.

Role of TRPV4-P2X7 Pathway in Neuropathic Pain in Rats with Chronic Compression of the Dorsal Root Ganglion.

Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable non-selective cation channel that is involved in the development of neuropathic pain. P2X7 receptor (P2X7) belongs to a class of ATP-gated nonselective cation channels that plays an important role in neuropathic pain. Nevertheless, little is known about the interaction between them for neuropathic pain. In this paper, we investigated role of TRPV4-P2X7 pathway in neuropathic pain. We evaluated the effect of TRPV4-P2X7 pathway on neuropathic pain in a chronic compression of the dorsal root ganglion (DRG) (hereafter termed CCD) model. We analyzed the effect of P2X7 on mechanical and thermal hyperalgesia mediated by TRPV4 in CCD. Furthermore, we assessed the effect of TRPV4 on the expression of P2X7 and the release of IL-1ß and IL-6 in DRG after CCD. We found that intraperitoneal injection of TRPV4 agonist GSK-1016790A led to a significant increase of mechanical and thermal hyperalgesia in CCD, which was partially suppressed by P2X7 blockade with antagonist Brilliant Blue G (BBG). Then, we further noticed that GSK-1016790A injection increased the P2X7 expression of CCD, which was decreased by TRPV4 blockade with antagonist RN-1734 and HC-067047. Furthermore, we also discovered that the expressions of IL-1ß and IL-6 were upregulated by GSK-1016790A injection but reduced by RN-1734 and HC-067047. Our results provide evidence that P2X7 contributes to development of neuropathic pain mediated by TRPV4 in the CCD model, which may be the basis for treatment of neuropathic pain relief.

Pathogenic Hydrogel? A Novel-Entrapment Neuropathy Model Induced by Ultrasound-Guided Perineural Injections.

Entrapment neuropathy (EN) is a prevalent and debilitative condition caused by a complex pathogenesis that involves a chronic compression-edema-ischemia cascade and perineural adhesion that results in excessive shear stress during motion. Despite decades of research, an easily accessible and surgery-free animal model mimicking the mixed etiology is currently lacking, thus limiting our understanding of the disease and the development of effective therapies. In this proof-of-concept study, we used ultrasound-guided perineural injection of a methoxy poly(ethylene glycol)-b-Poly(lactide-co-glycoilide) carboxylic acid (mPEG-PLGA-BOX) hydrogel near the rat's sciatic nerve to induce EN, as confirmed sonographically, electrophysiologically, and histologically. The nerve that was injected with hydrogel appeared unevenly contoured and swollen proximally with slowed nerve conduction velocities across the injected segments, thus showing the compressive features of EN. Histology showed perineural cellular infiltration, deposition of irregular collagen fibers, and a possible early demyelination process, thus indicating the existence of adhesions. The novel method provides a surgery-free and cost-effective way to establish a small-animal model of EN that has mixed compression and adhesion features, thus facilitating the additional elucidation of the pathophysiology of EN and the search for promising treatments.

A Special type of non-traumatic posterior interosseous nerve compression syndrome.

The posterior interosseous nerve (PIN) is the terminal branch of the radial nerve. The symptoms of PIN palsy vary markedly according to its types. In this report, we present the case of a 61-years-old male patient with an unusual manifestation of non-traumatic novel type of PIN palsy. A complicated course was involved in the diagnosis of this disease. The operation was performed after verification of PIN palsy. Recovery of symptoms was observed in a follow-up conducted three years later. Additionally, the electromyography examination returned to normal.

Peripheral Nerve Entrapment and Injury in the Upper Extremity.

Peripheral nerves in the upper extremities are at risk of injury and entrapment because of their superficial nature and length. Injury can result from trauma, anatomic abnormalities, systemic disease, and entrapment. The extent of the injury can range from mild neurapraxia, in which the nerve experiences mild ischemia caused by compression, to severe neurotmesis, in which the nerve has full-thickness damage and full recovery may not occur. Most nerve injuries seen by family physicians will involve neurapraxia, resulting from entrapment along the anatomic course of the nerve. In the upper extremity, the brachial plexus branches into five peripheral nerves, three of which are commonly entrapped at the shoulder, elbow, and wrist. Patients with nerve injury typically present with pain, weakness, and paresthesia. A detailed history and physical examination alone are often enough to identify the injury or entrapment; advanced diagnostic testing with magnetic resonance imaging, ultrasonography, or electrodiagnostic studies can help confirm the clinical diagnosis and is indicated if conservative management is ineffective. Initial treatment is conservative, with surgical options available for refractory injuries or entrapment caused by anatomic abnormality.

The role of structure and function changes of sensory nervous system in intervertebral disc-related low back pain.

Low back pain (LBP) is a common musculoskeletal symptom, which can be developed in multiple clinical diseases. It is widely recognized that intervertebral disc (IVD) degeneration (IVDD) is one of the leading causes of LBP. However, the pathogenesis of IVD-related LBP is still controversial, and the treatment means are also insufficient to date. In recent decades, the role of structure and function changes of sensory nervous system in the induction and the maintenance of LBP is drawing more and more attention. With the progress of IVDD, IVD cell exhaustion and extracellular matrix degradation result in IVD structural damage, while neovascularization, innervation and inflammatory activation further deteriorate the microenvironment of IVD. New nerve ingrowth into degenerated IVD amplifies the impacts of IVD-derived nociceptive molecules on sensory endings. Moreover, IVDD is usually accompanied with disc herniation, which could injure and inflame affected nerves. Under mechanical and pro-inflammatory stimulation, the pain-transmitting pathway exhibits a sensitized function state and ultimately leads to LBP. Hence, relevant pathogenic factors, such as neurotrophins, ion channels, inflammatory factors, etc., are supposed to serve as promising therapeutic targets for LBP. The purpose of this review is to comprehensively summarize the current evidence on 1) the pathological changes of sensory nervous system during IVDD and their association with LBP, and 2) potential therapeutic strategies for LBP targeting relevant pathogenic factors.

Wide distribution of central myelin segment along the facial nerve might explain hemifacial spasm with distal nerve compression.

INTRODUCTION: Many researchers have assumed that neurovascular compression of the facial nerve at the site covered by central myelin sheath causes hemifacial spasm. However, some cases do not correspond to this hypothesis. The aim of this study was to clarify the myelin histology in the facial nerve. MATERIALS AND METHODS: Histological analyses were conducted on 134 facial nerves from 67 cadavers. Three dimensions were measured in these sections: the length from the upper border of the medullopontine sulcus to the boundary between the central and peripheral myelin sheath along the anterior side; the length from the detachment point of the brain stem to the boundary along the posterior side; and the length of the transitional zone (TZ), known as the Obersteiner-Redlich zone. RESULTS: Of the 134 facial nerves, 41 were available for study. The length of the central myelin segment ranged from 4.62 to 12.6 mm (mean 8.06 mm; median 7.98 mm) along the anterior side and from 0.00 to 4.58 mm (mean 1.68 mm; median 1.42 mm) along the posterior side of the facial nerve, and the length of the TZ ranged from 0.00 to 2.76 mm (mean 1.51 mm; median 1.42 mm). CONCLUSIONS: In this study, the length of the central myelin segment in the facial nerve was found to be longer than that previously reported.

Clinical Importance of the Posterior Inferior Cerebellar Artery: A Review of the Literature.

The posterior inferior cerebellar artery (PICA), with its unique anatomical complexity, is of great clinical importance and involved in many diseases including aneurysm, ischemic stroke, neurovascular compression syndrome (NVCS), arteriovenous malformation (AVM), and brain tumor. However, a comprehensive systematic review of the importance of the PICA is currently lacking. In this study, we perform a literature review of PICA by searching all the associated papers in the PUBMED database hoping to provide a better understanding of the artery. The PICA has tortuous and variable course and territory, divided into 5 segments. Various aneurysms involving PICA were not uncommon, of which the treatment is challenging. The PICA infarct typically manifests lateral medullary syndrome (LMS) and is more likely to cause mass effects. The PICA frequently compresses the medulla and the cranial nerves resulting in various neurovascular compression syndromes (NVCS). Arteriovenous malformation (AVM) fed by PICA are associated with aneurysm and dissection which have high risk of rupture and worse outcome. PICA injured by head trauma can cause fatal SAH. VA terminating in PICA probably cause Bow hunter's syndrome (BHS). The PICA supplies many brain tumors and can be used in intracerebellar chemotherapy. The PICA can be exposed and injured during surgeries especially in telovelar approach, and it also plays an important role in bypass surgeries, hinting the surgical importance of PICA. In conclusion, PICA is very important in clinical practice.

Pain Syndromes Secondary to Cluneal Nerve Entrapment.

PURPOSE OF REVIEW: The purpose of this review is to provide an overview of the cluneal nerves, present a summary of pain syndromes secondary to clunealgia, and evaluate current literature for diagnostic and treatment modalities. RECENT FINDINGS: Multiple trials and studies have reported success with numerous modalities ranging from nerve blocks, neuroablation, and even peripheral neuromodulation with varying degrees of clinical benefit. Cluneal nerve entrapment or chronic impingement can cause buttock pain or referred pain to nearby areas including the lower back, pelvic area, or even the lower extremities. Clunealgias and associated pain syndromes can often be challenging to diagnose and differentiate. An appreciation of the pathophysiology of clunealgias can assist with patient selection for interventional pain strategies targeted towards the cluneal nerves, including nerve blocks, neuroablation, and peripheral neuromodulation. More research is needed to better delineate the efficacy of these procedures for clunealgias.

Ocular Hypertension, Glaucoma or Compressive Neuropathy in Patient with Active TED.

INTRODUCTION: Severe cases of thyroid eye disease with high intraocular pressure and visual field defects are a real diagnostic challenge requiring the exclusion of dysthyroid optic neuropathy and differential diagnosis with glaucoma. AIM: To report а case of a patient with active thyroid eye disease (TED), decreased visual acuity and elevated intraocular pressure. MATERIALS AND METHODS: We present a 52-year-old woman with TED in both eyes, class 2c3c4a6a (NOSPECS), with 6 points (by CAS) activity, who received corticosteroid therapy to a maximum cumulative dose of 5750 mg, with non-insulin-dependent diabetes mellitus and topical antihypertensive treatment with tapticom, brizadopt, and luxfen. The patient received full ophthalmological exam, tonometry, exophthalmometry, computer perimetry, optical coherence tomography (OCT) and computed tomography (CT) scan of orbits. RESULTS: The following results were obtained: BCVA of right eye = 0.6, BCVA of left eye = 0.3; TOD = 26 mm Hg and ТОS = 21 mm Hg; exophthalmometry: 30 mm for the right eye and 31 mm for the left one; diplopia in all directions, edema and hyperemia of the eyelids and conjunctiva, eyelids retraction, sluggish pupil reactions, normal color vision, transparent ocular media, indistinct borders of the optic nerve disc, without glaucomatous excavation, tortuosity and dilation of the venules, retina - without diabetic changes, maculas - with normal reflex; CP datа for a localized inferotemporal visual field defect, CT data for thickening of all extraocular muscles, soft tissue orbital edema, and optic nerves compression. CONCLUSION: Our results confirmed the presence of dysthyroid optic neuropathy based on the decreased visual acuity, ophthalmo-scopic evaluation of the optic nerve head, lack of glaucomatous OCT changes, atypical perimetric changes and the CT data. The optic neuropathy is the most severe complication in patients with TED which develops due to the compression of the optic nerve and/or its blood supply from the enlarged extraocular muscles and soft tissues in the orbital apex and due to the mechanical tension of the optic nerve in cases moderate or severe proptosis is present.

The Chiasmal Compression Index: An Integrative Assessment Tool for Visual Disturbances in Patients with Pituitary Macroadenomas.

OBJECTIVE: Visual status is routinely evaluated by neuro-ophthalmologic examination and computerized visual field (VF) tests in patients with chiasmal compression secondary to pituitary macroadenoma. Currently, no relevant data exists to accurately quantify the extent of optic apparatus compromise to further guide clinical decision-making. We aimed to assess for a possible quantitative correlation between optic chiasm geometric properties on magnetic resonance imaging (MRI) and VF deficits. METHODS: Visual assessments and concurrent MRI scans were retrospectively reviewed from patients treated for pituitary macroadenoma in a single medical institution. Chiasm width, chiasm minimal and maximal height, and chiasm angle were measured on MRI coronal plane images by 3 independent reviewers (for the sake of variability analysis). VF numerical summary parameters were also retrieved. RESULTS: A total of 30 patients were included in the final analysis. Average VF index was 70% (±30), and averaged mean deviation was 10.0 db (±9). Chiasm angle and width (which together represents the bending and stretching of the chiasm by the upward directed compression; both of which demonstrated high inter- and intraobserver agreement) showed strong correlation with VF loss. Chiasmal compression index derived from those parameters showed even stronger correlation. CONCLUSIONS: The strong correlation demonstrated by our results of this relatively simple radiologic measurement with VF status, despite the relatively small cohort, calls for further investigation in this promising direction, and may facilitate with basic assessment and clinical decision-making for patients with equivocal neuro-ophthalmologic evaluation, as well as with poor compliance.

Distal radius fractures: an evidence-based approach to assessment and management.

Distal radius fractures account for one in five bony injuries in both primary and secondary care. These are commonly the result of a fall on outstretched hands or high-energy trauma. On assessment, clinicians should determine the mechanism of injury, associated bony or soft tissue injuries, and neurovascular symptoms. Investigations should always include radiographs to evaluate for intra-articular involvement and fracture displacement. Owing to the heterogeneous injury patterns and patient profiles, the preferred management should consider the severity of the fracture, desired functional outcome and patient comorbidities. Non-operative management in select patients can give good results, especially in older adults. Immobilisation with or without reduction forms the mainstay of non-operative treatment. Surgical management options include closed reduction and application of a cast, percutaneous K-wires, open reduction and internal fixation with plates, or external fixation. Patients should be encouraged to mobilise as soon as it is safe to do so, to prevent stiffness. Median nerve compression is the most common complication followed by tendon rupture, arthrosis and malunion. This article outlines the British Orthopaedic Association Standards for Trauma and Orthopaedics for the management of distal radius fractures.

[Tarlov cyst and faecal incontinence: A case report and literature review]. / Quiste de Tarlov e incontinencia fecal: caso clínico y revisión de la literatura.

Tarlov, or perineural cysts, are lesions of the nerve root usually located at the sacral level of the spine. Their cause is unclear. These cysts are generally identified as an incidental finding and are usually asymptomatic. Symptomatic cysts are infrequent, with symptoms usually consisting of pain, radiculopathy and, less frequently, bladder, bowel and sexual dysfunction. We report the case of a 70-year-old woman with Tarlov cyst, provoking faecal incontinence, and review the aetiology, pathophysiology and management of this particular case.

(Cost-)effectiveness of lower extremity nerve decompression surgery in subjects with diabetes: the DeCompression (DECO) trial-study protocol for a randomised controlled trial.

INTRODUCTION: The peripheral nerves of patients with diabetes are often pathologically swollen, which results in entrapment at places of anatomical narrowing. This results in nerve dysfunction. Surgical treatment of compression neuropathies in the lower extremities (lower extremity nerve decompression (LEND)) results in relief of symptoms and gain in peripheral nerve function, which may lead to less sensory loss (short term) and less associated detrimental effects including foot ulceration and amputations, and lower costs (long term). The aim of the DeCompression trial is to evaluate the effectiveness and (cost-)effectiveness of surgical decompression of compressed lower extremity nerves (LEND surgery) compared with patients treated with conventional (non-surgical) care. METHODS AND ANALYSIS: A stratified randomised (1 to 1) controlled trial comparing LEND surgery (intervention) with conventional non-surgical care (control strategy) in subjects with diabetes with problems of neuropathy due to compression neuropathies in the lower extremity. Randomisation is stratified for participating hospital (n=11) and gender. Patients and controls have the same follow-up at 1.5, 3, 6, 9, 12, 18, 24 and 48 months. Participants (n=344) will be recruited in 12 months and enrolled in all affiliated hospitals in which they receive both the intervention or conventional non-surgical care and follow-up. Outcome assessors are blinded to group assignment. PRIMARY OUTCOME: disease-specific quality of life (Norfolk Quality of Life Questionnaire-Diabetic Neuropathy). SECONDARY OUTCOMES: health-related quality of life (EuroQoL 5-dimension 5-level (EQ-5D5L), 36-item Short Form (SF-36)), plantar sensation (Rotterdam Diabetic Foot Test Battery), incidence of ulcerations/amputations, resource use and productivity loss (Medical Cost Questionnaire, Productivity Cost Questionnaire) during follow-up. The incremental cost-effectiveness ratio will be estimated on the basis of the collected empirical data and a cost-utility model. ETHICS AND DISSEMINATION: Ethics approval has been granted by the Medical Research Ethics Committee of Utrecht University Medical Center (reference: NL68312.041.19v5, protocol number: 19-335/M). Dissemination of results will be via journal articles and presentations at national and international conferences. TRIAL REGISTRATION NUMBER: NetherlandsTrial Registry NL7664.

A Vascular Malformation in the Hand with Compromised Neurologic Status.

BACKGROUND: Vascular malformations of the hand are rare vascular malformations that are challenging to treat. METHODS: We present a case of a large vascular malformation with left hand pain and decreased sensation of the small and ring fingers. The lesion was treated operatively with surgical excision. RESULTS: The malformation was successfully removed surgically, and pain resolved and numbness recovered by 2 weeks after surgery. CONCLUSIONS: This is a rare case of large vascular malformation in the hand with compromised neurologic status. Surgical treatment provided complete relief of the disease, and the patient returned to normal daily activities.

Phenytoin Cream for the Treatment of Sciatic Pain: Clinical Effects and Theoretical Considerations: Case Report.

Chronic sciatic pain is difficult to treat. Patients often suffer from considerable pain and are severely hampered in their everyday activities. Most pharmacologic analgesic treatments have disappointing effects, and often are limited due to adverse events. New treatments are therefore needed. Surprisingly we found fast pain reduction after applying topical phenytoin cream at the painful dermatome in a 55-year-old patient suffering from sciatic pain due to pathology of a disc. This patient was treatment resistant for 13 years. Prescribing topical analgesic cream seemed to us at first sight quite counter-intuitive. The clear response in a treatment-resistant patient however provoked us to look deeper in the pathophysiology of sciatic nerve impingement. Recently it has been documented that proximal nerve lesions are followed by small fiber pathology in the skin. This might be a responsible peripheral wind-up generator for the chronification of pain in sciatic nerve compression. Topical application of the broad-acting voltage-gated sodium channel blocker phenytoin could reduce neuropathic pain in our case completely, supporting a peripheral mechanism of action for phenytoin cream in sciatic pain.