Proximal forearm nerve branching patterns: an anatomical study and its clinical significance.

OBJECTIVE: The aim of this study was to add to the understanding of nerve branching patterns in the proximal forearm and consider optimal nerve transfer options to address the various injuries that affect the function of the upper extremity. METHODS: Eleven upper-extremity cadaveric specimens were dissected to expose the radial, median, and ulnar nerves in the proximal forearm. The site of origin of nerve branches from the major nerves was assessed, with measurements made in reference to the lateral epicondyle for the radial nerve branches and the medial epicondyle for the median and ulnar nerve branches. The distances to where these branches entered their respective muscles (muscle entry point) were assessed using the same landmarks. To plan a transfer, the length of the nerve branches was then calculated as the difference from the apparent origin from the main nerve trunk to the location where the nerve entered the muscle. Importantly, the nerve branch origin was established as the location of obvious separation from the main nerve trunk without additional fascicular dissection from the major nerve trunk. The number of branches was determined, and the diameter for each branch was measured using a Vernier caliper. RESULTS: The radial nerve branch to the extensor carpi radialis brevis (ECRB) muscle had an average length of 50.7 mm and average diameter of 1.6 mm. The mean medial and lateral lengths of the radial branches to the supinator muscle were found to be 22.2 mm (diameter 1.4 mm) and 15.3 mm (diameter 1.3 mm), respectively. The anterior interosseous nerve (AIN) branch of the median nerve was found 67.8 mm distal to the medial epicondyle with a diameter of 2.3 mm. The flexor carpi ulnaris (FCU) muscle innervation from the ulnar nerve was provided by 3 or 4 branches in most specimens. The second and third of these branches were the longest, with means of 30.5 mm (diameter 1.4 mm) and 30.7 mm (diameter 1.3 mm), respectively. CONCLUSIONS: While there is variability of the nerve branching pattern in the proximal forearm between specimens, the authors provide evidence of commonalities (branching patterns and distances) that can facilitate planning for upper-extremity nerve reconstructions. Importantly, all measurements are provided with reference to easily identified bony landmarks and to their muscle entry points to aid operative decision-making. These data complement the growing practice of nerve transfers in the upper extremity for a variety of pathologies.

A standardized ultrasound approach in neuralgic amyotrophy.

Neuralgic amyotrophy (NA), also referred to as idiopathic brachial plexitis and Parsonage-Turner syndrome, is a peripheral nerve disorder characterized by acute severe shoulder pain followed by progressive upper limb weakness and muscle atrophy. While NA is incompletely understood and often difficult to diagnose, early recognition may prevent unnecessary tests and interventions and, in some situations, allow for prompt treatment, which can potentially minimize adverse long-term sequalae. High-resolution ultrasound (HRUS) has become a valuable tool in the diagnosis and evaluation of NA. Pathologic HRUS findings can be grouped into four categories: nerve swelling, swelling with incomplete constriction, swelling with complete constriction, and fascicular entwinement, which may represent a continuum of pathologic processes. Certain ultrasound findings may help predict the likelihood of spontaneous recovery with conservative management versus the need for surgical intervention. We recommend relying heavily on history and physical examination to determine which nerves are clinically affected and should therefore be assessed by HRUS. The nerves most frequently affected by NA are the suprascapular, long thoracic, median and anterior interosseous nerve (AIN) branch, radial and posterior interosseous nerve (PIN) branch, axillary, spinal accessory, and musculocutaneous. When distal upper limb nerves are affected (AIN, PIN, superficial radial nerve), the lesion is almost always located in their respective fascicles within the parent nerve, proximal to its branching point. The purpose of this review is to describe a reproducible, standardized, ultrasonographic approach for evaluating suspected NA, and to share reliable techniques and clinical considerations when imaging commonly affected nerves.

Diagnostic yield of nerve biopsy in the evaluation of peripheral neuropathies.

BACKGROUND: With progress made in neurogenetics and neuroinflammation, the indications and value of nerve biopsies in the diagnostic evaluation of peripheral neuropathies are less clear. In this study, we aimed to evaluate the diagnostic yield of nerve biopsies in patients with peripheral neuropathies. METHODS: We performed a retrospective review of nerve biopsy reports from April 1998 to June 2021 of patients with peripheral neuropathies presenting to the Department of Pathology, University of Malaya Medical Centre, Kuala Lumpur, Malaysia. The diagnostic value of the biopsies was determined based on the criteria by Midroni and Bilbao as follows: contributive (essential and helpful), non-contributive and inadequate. RESULTS: A total of 107 nerve biopsies were analysed. Sixty-four (60 %) were males and the mean age was 52 years, ranging from 13 to 86 years. Ninety-four (88 %) were sural nerve biopsies; and only one patient (1 %) each had superficial peroneal and superficial radial nerve biopsy. The indications for the procedure were vasculitis (34 %), peripheral neuropathy of unknown aetiology (34 %), amyloidosis (14 %) and chronic inflammatory demyelinating polyneuropathy (10 %). In 68 (63 %) biopsies, the diagnostic value was contributive. Of these, 28 (26 %) were essential and 40 (37 %) were helpful. In contrast, 35 (33 %) biopsies were non-contributive and 4 (4 %) were inadequate. In 66 % (71/107) of cases, the nerve biopsy did not reveal a definite pathological diagnosis. However, in the remainder, a diagnosis of vasculitis (18 %, 19/107), followed by amyloidosis (10 %, 11/107) could be determined. For 32/71 biopsies with undetermined pathological diagnosis, neuropathy remained cryptogenic in 22 % (7/32) upon follow up. CONCLUSIONS: With the exception of vasculitis and amyloidosis, there is limited value in performing nerve biopsies in the evaluation of patients with peripheral neuropathy. However, this should be interpreted with caution as the number of patients with a clinical diagnosis of vasculitis and amyloidosis were relatively larger than patients with other diagnosis. Refinement and careful selection of cases are required to increase the diagnostic yield of nerve biopsy.

Hourglass-Like Constriction Neuropathy of the Upper Limb Nerve: Diffusion-Weighted Magnetic Resonance Neurography Imaging Findings.

OBJECTIVE: The purposes of this study were to determine reliable diffusion-weighted magnetic resonance neurography (DW-MRN) features of hourglass-like constriction of the upper limb nerve and to evaluate the application value of DW-MRN compared with ultrasonography (US). METHODS: We retrospectively reviewed MRN studies of 13 patients. Qualitative and quantitative image analyses were carried out. The number of constrictions based on DW-MRN and US findings was compared. RESULTS: Of the 13 cases, there were 7 cases with radial nerve abnormalities, 4 with median nerve abnormalities, and 2 with radial and median nerve abnormalities. Diffusion-weighted MRN showed a single-segmental constriction in 7 of 13 cases and multisegmental constrictions in 6 of 13 cases; the hourglass-like constriction appeared in all cases (13 of 13). Thirty-three nerve constrictions were found in DW-MRN, and 29 nerve constrictions were found in US. CONCLUSIONS: Diffusion-weighted MRN is a noninvasive and helpful diagnostic for hourglass-like constriction of the upper limb nerve.

Porphyric neuropathy.

Acute hepatic porphyrias are inherited metabolic disorders that may present with polyneuropathy, which if not diagnosed early can lead to quadriparesis, respiratory weakness, and death. Porphyric neuropathy is an acute to subacute motor predominant axonal neuropathy with a predilection for the upper extremities and usually preceded by a predominantly parasympathetic autonomic neuropathy. The rapid progression and associated dysautonomia mimic Guillain-Barré syndrome but are distinguished by the absence of cerebrospinal fluid albuminocytologic dissociation, progression beyond 4 wk, and associated abdominal pain. Spot urine test to assess the porphyrin precursors delta-aminolevulinic acid and porphobilinogen can provide a timely diagnosis during an acute attack. Timely treatment with intravenous heme, carbohydrate loading, and avoidance of porphyrinogenic medications can prevent further neurological morbidity and mortality.

Long-Term Outcomes after Surgical Treatment of Radial Sensory Nerve Neuromas: Patient-Reported Outcomes and Rate of Secondary Surgery.

BACKGROUND: This study aimed to (1) describe long-term patient-reported outcomes of surgically treated symptomatic radial sensory nerve neuromas on function, pain interference, pain intensity, and satisfaction; (2) assess which factors were associated with worse function, higher pain intensity, and more pain interference; and (3) describe the secondary surgery rate and factors associated with secondary surgery. METHODS: The authors conducted a retrospective review of patients surgically treated for radial sensory nerve neuroma from 2002 to 2016 (n = 54). Twenty-five of these 54 patients completed a follow-up survey including the Patient-Reported Outcomes Measurement Information System (PROMIS) upper extremity, pain interference, and depression scales; numerical rating scale pain and satisfaction instruments; and the global rating scale of change, at a mean period of 10.7 ± 4.3 years after neuroma surgery. RESULTS: The mean PROMIS scores were 45.0 ± 12.1 for upper extremity, 55.5 ± 10.3 for pain interference, and 49.9 ± 10.2 for depression, and were within 1 SD of the general population. Eight patients (32 percent) reported symptoms as unchanged or worse following neuroma surgery. The median numerical rating scale pain was 3 (interquartile range, 1 to 6) and the global rating scale of change satisfaction was 10 (interquartile range, 7 to 10). Older patients (p = 0.002) and patients with higher PROMIS pain interference (p < 0.001), higher numerical rating scale for pain (p = 0.012), and lower global rating scale of change scores (p = 0.01) had worse PROMIS upper extremity scores. The secondary surgery rate was 20 percent and was associated with the presence of multiple neuromas (p = 0.001). CONCLUSIONS: Radial sensory nerve neuromas remain difficult to treat. They have a high secondary surgery rate (20 percent), with only 68 percent of patients reporting improvement after surgical intervention. Patient-reported outcomes after surgery are similar to conditions of the general population; however, the range of outcomes is wide.

Leiomyoma of digit of hand: Report of three cases with literature review.

Leiomyoma is a benign tumor of smooth muscle origin most common in areas of the body with abundant smooth muscle including the gynecologic, genitourinary, and gastrointestinal system. Leiomyoma outside of these locations is believed to arise from vascular smooth muscle and arrector pili muscles. Leiomyoma of an extremity is a rare diagnosis, especially when present in a digit of the hand due to the paucity of smooth muscle in this location. We report three cases of leiomyoma of a digit of the hand.

Epineural glomus tumor of the posterior interosseous nerve: Case report.

Among peripheral nerve sheath tumors, epineural glomus tumors represent a rare differential diagnosis for peripheral nerve schwannoma, displaying the same appearance on MRI. Here we present the case of a 68-year-old man complaining of pain in the left forearm, with paresthesias in the first three fingers. MRI demonstrated a round mass along the course of the posterior interosseous nerve with homogeneous contrast enhancement. Complete surgical removal successfully relieved the symptoms. Pathological analysis led to the diagnosis of glomus tumor of uncertain malignant potential. This is to our knowledge the first reported case of epineural glomus tumor of the radial nerve.

Ipsilateral radial nerve, median nerve, and ulnar nerve injury caused by crush syndrome due to alcohol intoxication: A case report.

RATIONALE: Autologous peripheral nerve injury caused by crush syndrome due to alcohol intoxication is relatively rare, and to our knowledge, the compression of 3 upper limb nerves at the same time has not been reported previously. If a compressive peripheral nerve injury is not treated in a timely manner, it is difficult to recover neurological function, and the prognosis is poor. PATIENT CONCERNS: Here, we present a case of a 50-year-old man with ipsilateral radial nerve, median nerve, and ulnar nerve injuries caused by autogenous compression after drunkenness. DIAGNOSIS: Electromyography and nerve conduction studies suggested peripheral nerve injury in the left upper limb. The diagnosis was injury to the radial nerve, median nerve, and ulnar nerve in the left upper arm. INTERVENTIONS: Exploratory neurolysis surgery of the radial nerve, median nerve, and ulnar nerve was performed in the left upper arm. Postoperative oral neurotrophic drugs were administered, and functional exercise was performed. OUTCOMES: After timely diagnosis and treatment, the strength of the left upper arm muscle recovered, and the prognosis of neurological function was satisfactory during 3 years of follow-up sessions. LESSONS: In the treatment of such patients, a comprehensive understanding of their medical history and a strict physical examination should be performed. Combined with neuroelectrophysiological and imaging examination, the diagnosis can be confirmed. After timely diagnosis and treatment, the prognosis is mostly excellent.

The casual association of cervical spinal cord ischemia and axonal degeneration in second motor neuron following subarachnoid hemorrhage: Experimental study.

AIM: Muscle abnormalities after spinal cord ischemia caused by subarachnoid hemorrhage (SAH) have not been explored for degenerative variations in the soma of second motor neurons of the spinal cord gray matter. This study aimed to investigate histopathological alterations in the gray matter and the role of peripheral nerves in SAH. MATERIAL AND METHODS: Twenty-two rabbits were allocated in the control (Group I, n = 5), SHAM (Group II, n = 5), and research (Group III, n = 12) groups. Muscle weakness of the upper extremities innervated by radial nerves was evaluated at the initial day, and outcomes were recorded as control data. Re-measurements were done after injecting 0.5 ml of SF for SHAM and autolog artery blood inside craniocervical subarachnoid space for the study group. After 3 weeks, radial nerve roots, their ganglia, and segments of the spinal cord around C5-6 root entry zones were extracted bilaterally. Degenerated second motor neuron somas and the degenerated radial nerve motor axons at the intervertebral foramen were assessed. RESULTS: The average degenerated soma intensity/mm3 at the C5-6 levels in the spinal cord was 2 ±â€¯1/mm3, 13 ±â€¯4/mm3, and 56 ±â€¯10/mm3 for Groups I, II, and Group III. The average degenerated axon intensity of radial nerves was 3 ±â€¯1/mm2, 34 ±â€¯9/mm2, and 234 ±â€¯78/mm2 for Groups I, II, and III. CONCLUSION: Gray matter ischemia in the spinal cord may lead to axonal deterioration on equal levels at the peripheral nerves with advanced SAH. Detected or undetected spinal SAH should be considered an important factor on the etiology of second motor neuron diseases.

Quantifying the Location of the Radial Nerve in Children for Intraoperative Use.

BACKGROUND: In adults, a relative "safe zone" for lateral approaches to the elbow has been well described in efforts to reduce iatrogenic injury, typically a minimum of 6 cm proximal to the lateral epicondyle. To avoid iatrogenic injury to the radial nerve intraoperatively, we investigated the distance of the nerve from the distal humeral physis in children. METHODS: All patients who had axial and coronal T1-weighted magnetic resonance imagings of the humerus and elbow between 2005 and 2015 were eligible. Patients were excluded if there was any pathology causing significant alteration to the normal anatomy of the distal humerus or surrounding soft tissue. The axial cut in which the radial nerve was positioned along a line passing through the center of the humerus in the transverse plane was identified, and the location of the nerve was marked. This axial cut was cross-referenced with the corresponding coronal view. The distance along the lateral edge of the humerus in a straight line from the marked location of the radial nerve to the distal humeral physis was measured. RESULTS: In total, 21 magnetic resonance imagings of 20 patients met the inclusion criteria. The mean distance of the radial nerve proximally from the distal humeral physis was as follows by age group: below 1-year old=1.7 cm (range, 1.2 to 2.5 cm); 1 to 2-years old=2.8 cm (range, 1.8 to 3.2 cm); 4 to 5-years old=5.3 cm (range, 5.1 to 5.5 cm); 6-years old and above=7.3 cm (range, 6.0 to 9.2 cm). For below 6-years old, when age was multiplied by 1 cm to define a predicted safe zone all radial nerves were found proximal to this. All patients 6 years and above had measurements that fell into the adult range of >6 cm, whereas no patients below 6-years old had measurements in this range. CONCLUSIONS: The distance of the radial nerve proximally from the distal humeral physis can be safely approximated for children below 6 years of age by multiplying patient age in years by 1 cm. By the age of 6 the distance of the radial nerve falls within the adult range (>6 cm). LEVEL OF EVIDENCE: Level III.

High-resolution ultrasonography and shear-wave sonoelastography of a cystic radial nerve Schwannoma.

Peripheral nerve tumors are often evaluated with magnetic resonance imaging (MRI), although there are many advantages offered with high-resolution ultrasonography (HRUS). This case report emphasizes the value of HRUS in the diagnosis and management of a patient with a cystic radial nerve Schwannoma. In addition, information on tumor stiffness, obtained with shear-wave sonoelastography (SWE), is presented.

El neuroma de la porción distal del nervio interóseo posterior como causa de dolor dorsal persistente de muñeca / Neuroma of the distal posterior interosseous nerve as a cause of persistent dorsal wrist pain

El dolor en el dorso de la muñeca es una causa frecuente de consulta médica en nuestra práctica clínica habitual. Normalmente este dolor puede ser debido a procesos traumáticos, inflamatorios o degenerativos. Pero en ocasiones el origen del dolor se aleja de estas causas frecuentes. Presentamos un caso de dolor crónico al nivel dorsal de muñeca sin claro antecedente traumático ni componente degenerativo o inflamatorio atribuible. Siendo de etiología neuropática, debido a un neuroma del nervio interóseo posterior precapsular. Se discuten posibles causas, métodos de diagnóstico y opciones de tratamiento (AU)

Dorsal wrist pain is a very common cause of complaint in the clinical practice of the hand surgeon. Such pain can frequently be related to traumatic, inflammatory or degenerative diseases, but sometimes its origin is far away from these common causes. A rare case is reported of chronic dorsal wrist pain of neuropathic origin, due to a pre-capsular neuroma of the posterior interosseous nerve. Possible causes, diagnostic hints, and treatment options are thoroughly discussed (AU)