Neurovascular Contacts in the Pathophysiology of Neuralgic Amyotrophy: An Observational Study.

Neurovascular conflict is considered one of the main causes of Trigeminal neuralgia, and 3D fast imaging employing steady-state acquisition magnetic resonance imaging (MRI) is the diagnostic imaging of choice. However, no tool is available to confirm imaging findings as the primary cause of trigeminal neuralgia because neurovascular contact is frequently found in asymptomatic individuals, according to some literature, although very little data is available till now. Therefore, we aim to determine the frequency of trigeminal neurovascular contact, involved nerve segment, culprit vessel, and characteristics of contacts in asymptomatic individuals. Knowledge about this is very crucial so that every patient may not be labeled as having neurovascular conflict as the primary cause and can be saved from unnecessary surgeries. A retrospective observational study was conducted on 105 MRI brain scans of asymptomatic individuals for trigeminal neurovascular relationships by two expert neuro-radiologists. Percentages calculated for categorical variables and for continuous variables Shapiro-Wilk test were used. The Fisher Exact test is used to assess the association between conflict and other variables. Inter-rater reliability was computed for the outcome and other variables and Cohen's kappa to evaluate the strength of agreement. All calculations were performed using STATA version 17.0. Out of 105 cases, neuro-vascular contact was identified in 64 cases. The most common contacting vessel was the superior cerebellar artery. The most common nerve segment involved was the cisternal segment, followed by the Root entry zone and porous trigeminus. In about 54 cases, the vessel was abutting the nerve, while in eight cases, it was compressing and, in two cases, displacing the nerve. The superior surface of the nerve was commonly involved. The inter-rater reliability between both neuroradiologists showed significant agreement. Neurovascular contact is found in asymptomatic individuals, so just the presence of contact in symptomatic individuals on MRI should not be considered as only the cause of trigeminal neuralgia. It is important to identify nerve thinning and distortion, which are more reliable signs.

Surgical Outcomes of Revision Microvascular Decompression for Persistent or Recurrent Hemifacial Spasm After Surgery: Analysis of Radiologic and Intraoperative Findings

Diagnostic capabilities of MRI for recognition of neurovascular conflict in patients with classical trigeminal neuralgia (CTN) are still discussed. Analyzing the anatomical relationships of trigeminal nerve root (TNR) with superior cerebellar artery (SCA) on 100 facial specimens of persons without CTN, the authors describe various neurovascular contacts. Some ones can transform into neurovascular conflict as damping properties of arterial wall are lost in accordance with hydrodynamic laws. The authors described 2 variants of neurovascular conflict between TNR and SCA after microvascular decompression in 100 patients. Both variants were diagnosed after CT angiography. The first type is observed only in patients with CTN (65% of cases). The second type is observed in 35% of patients with CTN, but it also occurs on the intact side and in people without CTN. FIESTA imaging does not provide adequate data on neurovascular conflict. The authors believe that MRI programs providing quantitative characterization of TNR demyelination at the site of neurovascular conflict will be valuable to differentiate neurovascular contact from neurovascular conflict.

Superior oblique myokymia is a rare movement disorder thought to be caused by vascular compression of the trochlear nerve. Direct display of such neurovascular compression by magnetic resonance imaging has been lacking. The goal of this study was to assess the presence of neurovascular contacts in patients with superior oblique myokymia, using a specific magnetic resonance imaging protocol. A total of 6 patients suffering from right superior oblique myokymia underwent detailed neuro-ophthalmological examination, which showed tonic or phasic eye movement. All patients underwent magnetic resonance imaging, using a magnetic resonance imaging Fourier transform constructive interference in steady-state sequence in combination with magnetic resonance imaging time of flight magnetic resonance arteriography both before and after the administration of Gd-DTPA. With this protocol, the trochlear nerve could be visualized on 11 of 12 sides (92%). Arterial contact was detected at the root exit zone of the symptomatic right trochlear nerve in all 6 patients (100%). No arterial contact was identified at the root exit zone of the asymptomatic left trochlear nerve in any of the 5 left nerves visualized. In conclusion, superior oblique myokymia can result from neurovascular contact at the root exit zone of trochlear nerve, and therefore should be considered among the neurovascular compression syndromes.

With increasing use of cross-sectional imaging, a thorough knowledge of the normal anatomy and its variation is crucial to obtain proper differential diagnosis without ‘pathologizing’ common variant anatomy. In our daily reporting of magnetic resonance imaging (MRI) scans of the brain, we frequently observed neurovascular contacts between an elongated vertebral artery and the medullary oblongata in patients without obvious neurological symptoms. In contrast, this finding has been linked to neurological symptoms [1]. To study this finding, brain MRI scans of 100 consecutive patients without clinical neurological findings undergoing staging because of lung cancer were retrospectively assessed. The patient sample consisted of 58 men and 42 women with a mean age of 66.6 years (range 44–84 years). All patients were examined on the same 1.5 T MRI using a basic T2-weighted sequence with a slice thickness of 5 mm. All images were viewed on a standard medical workstation using the departmental PACS. A contact of a vertebral artery with the adjacent brain stem causing a visible impression of the brain parenchyma was found in 25 patients (25 %) (Fig. 1). The right side of the brain stem was affected in 13 and the left side in 12 patients. In none of the cases, an edema of the compressed brain stem was found. The mean age of patients with contact of a vertebral artery to the brain stem was higher (70.4 years) than in patients without contact (66.2 years). Despite this high incidence of asymptomatic brain stem compression to an elongated vertebral artery, symptomatic cases responding to microvascular decompression have been reported [2]. This phenomenon is not unknown in other cases of neurovascular compression syndromes. For example, trigeminal neuralgia due to a neurovascular conflict is an established diagnosis. Nonetheless up to 87.5 % of asymptomatic individuals may show a vascular compression of the trigeminal nerve [3]. Recent reports stressed that secondary imaging signs like nerve atrophy, alteration in fractional anisotropy, and the diffusion capacity may be suggestive of a symptomatic neurovascular contact in the case of trigeminal neuralgia [4]. In a reported case of a symptomatic neurovascular contact of an elongated vertebral artery, the compressed medulla showed edematous changes [5]. In contrast, in the case series of Savitz et al., no signal alteration of the compressed brainstem was reported or visible in the presented figures [1]. The found high prevalence in our small study and the contrasting small number of case reports may indicate the limited clinical significance of this finding in most patients. Without the secondary sign of local edema, causal relationship in the case of otherwise unexplained neurological findings should be made cautiously. Interestingly, hypertension has been repeatedly linked to vascular compression of the medulla oblongata, but no differences in the frequency of neurovascular compression have been found in a study comparing individuals with and without hypertension [6]. These findings support the assumption of an anatomical variation without clinical significance in most cases. Limitations of this study are the retrospective design, and the fact that patients in the setting of a recently diagnosed lung cancer may have not adequately reported subtle neurological symptoms. & J. Gossner johannesgossner@gmx.de

Superior oblique myokymia: magnetic resonance imaging support for the neurovascular compression hypothesis. Yousry I, Dieterich M, Naidich TP, Schmid UD, Yousry TA. Ann Neurol 2002;51:361–368

Perivascular neurons instruct 3D vascular lattice formation via neurovascular contact

Neuralgic amyotrophy (NA) is an uncommon neurological disorder characterized by acute pain followed by muscle weakness and atrophy. Advanced imaging techniques, such as ultrasound and MRI, can reveal structural nerve abnormalities including fascicular enlargement [1, 2]. Nerve ultrasound findings of fascicular entwinement (the abnormal rotation of nerve fascicles), or fascicular constriction, are quite specific to NA and may have implications for diagnosis and management [2]. We present a case of NA following coronary artery bypass grafting (CABG), with persistent nerve constriction noted on ultrasound despite clinical improvement. A 68-year-old male with a history of diabetes and idiopathic thrombocytopenic purpura developed severe left arm and forearm pain lasting for a week, beginning four days after undergoing coronary artery bypass grafting (CABG), followed by progressive weakness in left wrist and finger extension and hand numbness. Electrodiagnostic testing conducted 2 months post symptoms onset revealed a non-localizing, subacute, proximal left radial nerve injury. Brachial plexus MRI was unrevealing. Upon referral to a neuromuscular specialist four months post-surgery, he exhibited persistent weakness in left finger extension, grade 3/5 on the Medical Research Council (MRC) Scale for Muscle Strength, along with atrophy involving forearm and intrinsic hand muscles. Although the radial nerve was most involved, there were milder, widespread motor deficits in the left arm, in keeping with NA. A repeat electrodiagnostic study five months post-symptom onset demonstrated a low radial compound muscle action potential (CMAP), which had improved compared to the prior study, and preserved left radial sensory response. Clinically, he improved in left finger extension (MRC grade 4/5). An ultrasound of the left radial nerve, using a 12–22 MHz linear transducer, revealed two focal regions of nerve constriction between the spiral groove and antecubital fossa. Figure 1 demonstrates one of these regions, with an incomplete fascicular constriction and an hourglass deformity. Surrounding the constriction, the fascicle demonstrated increased cross-sectional area and reduced echogenicity (Figure 2). Increased Doppler signal within or surrounding a nerve, representative of abnormal vascularity, is often seen in inflammatory nerve conditions. In this case, the absence of a Doppler signal along the course of the left radial nerve may indicate chronicity [2]. In NA, nerve enlargements are the most common ultrasound finding, followed by constriction, and fascicular entwinement is the least common [3]. There was no fascicular entwinement noted through the extent of the left radial nerve. The superficial radial and posterior interosseous nerves appeared normal distally. This case highlights the utility of ultrasound in identifying sonographic features of NA. The presence of both nerve constriction and enlargement in our patient raises the question of whether these findings reflect differential involvement of individual fascicles versus the entire nerve or represent stages in a stepwise pathological progression. The nerve lesions were distal to the brachial plexus, and out of field for the brachial plexus MRI. Surgical treatment for nerve constrictions may be considered, but this patient had clinical improvement despite persistent nerve constrictions. Understanding the imaging characteristics of NA can aid in diagnosis and may inform treatment decisions. Further research is needed to clarify the prognostic implications of nerve constriction in NA. The authors declare no conflicts of interest.

Although neurovascular compression of the cochlear nerve (NVC-C) presenting as typewriter tinnitus is a discrete disease category, verified diagnostic criteria are lacking. We sought to refine the diagnostic criteria for NVC-C by reference to a relatively large case series. The medical records of 22 NVC-C patients were retrospectively reviewed. Psychoacoustic characteristics, the results of diagnostic work-up (including audiovestibular neurophysiological tests and radiological evaluations), and the initial treatment response to carbamazepine were investigated. All subjects described their tinnitus as a typical “typewriter” or “staccato” sound. Of the 22 subjects, 11 (50%) had histories of vertiginous spells, but none had ipsilesional hearing loss. Vestibular function tests in 11 subjects tested revealed only 2 (18.2%) isolated cervical vestibular evoked myogenic potential abnormalities. Radiological comparisons of the symptomatic and asymptomatic sides, regarding the type of the vascular loop and neurovascular contact, revealed no significant differences. However, all 22 subjects exhibited immediate and marked responses to short-term carbamazepine treatment. Meticulous history-taking in terms of the psychoacoustic characteristics and the response to initial carbamazepine, are more reliable diagnostic clues than are radiological or neurophysiological data in NVC-C subjects. Therefore, the typical psychoacoustic characteristics and the response to initial carbamazepine should be included in the diagnostic criteria.

Background: Neuralgic amyotrophy (NA) is an acute, monophasic, painful inflammatory dysimmune focal, or multifocal mononeuropathy. The lesion in NA is not always restricted to the brachial plexus but also involves individual nerves or branches. The prognosis of NA is less favorable than previously assumed, but the reasons for poor recovery remain unknown. Nerve constriction may be one of the causes of poor prognosis in NA.Case Presentation: Herein, we described a 54-year-old male with a history of type 2 diabetes in whom bilateral neuralgic amyotrophy developed with constriction of the posterior interosseous fascicle within the radial nerve. The patient experienced sudden-onset severe pain in both shoulders followed, 2 days later, by weakness in bilateral shoulders and the left forearm extensors over the subsequent month. The left forearm extensors were more severely affected than both shoulder girdle muscles. He noted a 7-kg weight loss for 1 month before pain onset. After diagnosing diabetic NA based on the clinical symptoms, imaging, and electrophysiological studies, treatment with systemic steroids improved pain and weakness in both shoulder muscles. Weakness in the left forearm extensors persisted after 1 month of steroid treatment. Follow-up ultrasound revealed constriction of the posterior interosseous fascicle within the main trunk of the left radial nerve at the elbow. Surgical exploration at 6 months after onset identified fascicle constriction, for which neurolysis was performed. Weakness in the extensors of the wrist and fingers did not improve during the 16-month follow-up.Conclusion: A single constriction of the fascicle within a peripheral nerve may often be under-recognized if NA presents with variable degrees of weakness in bilateral upper limbs. Furthermore, fascicular constriction without edema of the parent nerve may be easily missed on the initial ultrasound. A lack of early recognition of nerve constriction and delay in surgical intervention can result in unfavorable outcomes. The physician should consider the possibility of the fascicular constriction when evaluating patients suspected of brachial NA with significant weakness in the distal upper limb compared to the proximal weakness or weakness of the distal upper limb that does not improve over time.

Hourglass-like constrictions (HGCs) of involved nerves in neuralgic amyotrophy (NA) (Parsonage-Turner syndrome) have been increasingly recognized with magnetic resonance neurography (MRN). This study sought to determine the sensitivity of HGCs, detected by MRN, among electromyography (EMG)-confirmed NA cases. This study retrospectively reviewed records of patients with the clinical diagnosis of NA, and with EMG confirmation, who underwent 3-Tesla MRN within 90 days of EMG at a single tertiary referral center between 2011 and 2021. "Severe NA" positive cases were defined by a clinical diagnosis and specific EMG criteria: fibrillation potentials or positive sharp waves, along with motor unit recruitment (MUR) grades of "discrete" or "none." On MRN, one or more HGCs, defined as focally decreased nerve caliber or diffusely beaded appearance, was considered "imaging-positive." Post hoc inter-rater reliability for HGCs was measured by comparing the original MRN report against subsequent blinded interpretation by a second radiologist. A total of 123 NA patients with 3-Tesla MRN performed within 90 days of EMG were identified. HGCs were observed in 90.2% of all NA patients. In "severe NA" cases, based on the above EMG criteria, HGC detection resulted in a sensitivity of 91.9%. Nerve-by-nerve analysis (183 nerve-muscle pairs, nerves assessed by MRN, muscles assessed by EMG) showed a sensitivity of 91.0%. The second radiologist largely agreed with the original HGC evaluation, (94.3% by subjects, 91.8% by nerves), with no significant difference between evaluations (subjects: χ2 = 2.27, P = .132, nerves: χ2 = 0.98, P = .323). MRN detection of HGCs is common in NA.

Neuralgic amyotrophy (NA), also known as acute brachial plexitis, is postulated as an autoimmune pathogenesis. In a well-defined cohort of patients with NA, we analyzed the cerebrospinal fluid (CSF) profile and the prevalence of antiganglioside antibodies. Patients with Varicella zoster-associated radiculitis and healthy blood donors served as controls. An abnormal routine laboratory CSF profile was found in 29% of those with NA, mostly showing a disruption of the blood-brain barrier. Antibodies predominantly from the immunoglobulin M (IgM) isotype against at least one human ganglioside were detected in 36% of sera from patients with NA but in only 2% of controls. An NA-specific reactivity pattern was not detected, and there was no significant association with clinical or CSF parameters. This suggests that the seroprevalence of antiganglioside autoantibodies in patients with NA is nonspecific.

Nonsystemic vasculitic neuropathy (NSVN) is an under-recognized single-organ vasculitis of peripheral nerves that can only be diagnosed with a nerve biopsy. A Peripheral Nerve Society guideline group published consensus recommendations on the classification, diagnosis and treatment of NSVN in 2010, and new diagnostic criteria for vasculitic neuropathy were developed by the Brighton Collaboration in 2015. In this Review, we provide an update on the classification, diagnosis and treatment of NSVN. NSVN subtypes include Wartenberg migratory sensory neuropathy and postsurgical inflammatory neuropathy. Variants include diabetic radiculoplexus neuropathy and - arguably - neuralgic amyotrophy. NSVN with proximal involvement is sometimes termed nondiabetic lumbosacral radiculoplexus neuropathy. Cutaneous polyarteritis nodosa and other skin-nerve vasculitides overlap with NSVN clinically. Three patterns of involvement in NSVN have been identified: multifocal neuropathy, distal symmetric polyneuropathy, and overlapping multifocal neuropathy (asymmetric polyneuropathy). These patterns lack standard definitions, resulting in inconsistencies between studies. We propose definitions and provide an up-to-date differential diagnosis of multifocal neuropathy. Available evidence suggests that NSVN and neuropathy-predominant systemic vasculitis might be controlled better by treatment with corticosteroids and an immunosuppressive agent than with corticosteroids alone. Treated NSVN rarely spreads to other organs, but 30% of patients experience a relapse. Long-term neurological outcome is favourable, but chronic pain is common.

A family with neuralgic amyotrophy (idiopathic brachial plexus neuropathy) associated with a multifocal sensory neuropathy is described. Four members over two generations were affected by neuralgic amyotrophy, inherited as an apparent autosomal dominant trait; two also had a multifocal relapsing sensory neuropathy with the clinical features of Wartenberg's migrant neuropathy.

Viral communication has experienced noticeable changes since its first definition by Rushkoff in 1994. Some changes have been of such a nature that they have rendered the notions employed at the end of the last century and at the start of the 21st century obsolete. This present article tries to update and synthesize the concept of virality as the backbone of the current forms of communication and, especially, those that are born and triggered in social networks. For this we will use a classic bibliographic review methodology, which will try to investigate the background, the elements and the foundations of the concept. As a result of this revision, we will extract a new concept of viral communication, as a form of integration between the media and their messages or, also, as a form of global hybridization. In this context, the article will try to establish the theoretical foundations of virality as a paradigm of digital and connected communication. Personal communication, originally developed from leader theory and personal influence starting with contacts in close proximity (word-of-mouth), is redefined by the Internet and by the application of marketing (which has developed it under the name of permission or relational). With its rapid expansion in the early 1990s, the phenomenon of personal influence took on a new dimension. This happened mainly because the Internet is essentially a decentralized structure, where the nodes and points of influence are crucial for the flow of information. So we must think of network-based communication as a collaborative process. These forms of communication stand out for requiring personal information and allowing segmentation of the public and personalization of communication related actions.