Anatomical variability and histological structure of the ulnar nerve in the Guyon's canal

Ethics on academic procurement of cadavers

Anatomy is a vital discipline in the realm of Medicine, and its primary means of study is through the use of cadavers. Experts in the medical, legal, and ethical domains have discussed the use of cadavers or their anatomical parts for educational purposes, which are considered a severe drawback. The advantages of using cadavers include their contribution to medical education, research, the investigation of innovative surgical procedures or techniques, the detection of anatomical differences at an individual or population level, the enhancement of surgical skills, and the support of other anatomical investigations. This review highlights the issues like consent, respect for the deceased and cultural beliefs on cadaver procurement practices and also it emphasizes the need for better body donation initiatives and public awareness campaigns to ensure sustainable cadaver procurement practices, ensuring consent, respect for the deceased and cultural beliefs.

Compressive Neuropathies of the Upper Extremity: Anatomy for the Peripheral Nerve Surgeon

Advance knowledge of anatomy is a prerequisite for the peripheral nerve surgeon. This article serves to provide an outline of anatomic regions where nerve entrapment or compression can occur. Each section is subdivided into anatomic regions where the etiology, indications, and relevant and aberrant anatomy are discussed, as well as common surgical approaches to the problematic anatomic site. The purpose is to provide an overview for the peripheral nerve surgeon and offer a valuable resource to provide a better understanding and optimal care for this patient population.

Ultrasound of the Ulnar Nerve: A Pictorial Review: Part 1: Normal Ultrasound Findings

This is the first of a two-part article in which we focus on the ultrasound (US) appearance of the normal ulnar nerve (UN) and its main branches. The detailed US anatomy of the UN course is presented with high-resolution US images obtained with the latest-generation US machines and transducers.

High-resolution ultrasound and magnetic resonance imaging of ulnar nerve neuropathy in the distal Guyon tunnel

OBJECTIVE

The aim of the present study is to describe the ultrasound (US) and magnetic resonance imaging (MRI) findings in patients with neuropathies affecting the deep (DB) and superficial (SB) branches of the Ulnar nerve (UN) and to investigate the potential role of imaging modalities in the diagnostic workup of these conditions.

MATERIALS AND METHODS

We screened our institutional imaging database to identify patients with a diagnosis of UN mononeuropathy, and among them, we reviewed the cases where US disclosed pathological findings affecting the UN terminal divisions. In this latter subgroup, we retrieved available data on MRI and electrodiagnostic tests performed by the patients during the diagnostic workup. All the patients were evaluated with US machines equipped with 17-5-MHz, 18-4-MHz, 24-8-MHz, or 22-8-MHz probes. MRI exams were performed on a 3-T unit equipped with a 64-channel head RF coil.

RESULTS

Among 166 patients with UN mononeuropathy, we retrieved 15 patients (9%) for which US detected pathological findings affecting the UN terminal divisions, consisting of 7 cases of DB neuropathy, 4 cases of SB neuropathy, and 4 cases of combined neuropathy involving both nerves. Seven (46.7%) patients were submitted to MRI to integrate US findings. Among patients with SB and DB neuropathies, imaging allowed the identification of 7 traumatic nerve injuries, 2 nerve tumors, and 6 entrapment neuropathies, including 4 cases of nerve compression by a ganglion cyst.

CONCLUSION

High-resolution US and MRI are accurate modalities for the investigation of patients with SB/DB neuropathy, can provide critical information on the cause of nerve damage, and guide therapeutic decisions.

CRITICAL RELEVANCE STATEMENT

High-resolution US and MRI are accurate modalities for the investigation of patients with superficial/deep branch of the ulnar nerve neuropathy. In the proper setting, US may be regarded as a first-line approach in patients with suspected neuropathies affecting these small branches.

KEY POINTS

• Neuropathies affecting the distal ulnar nerve often require multimodal investigations. • US and MRI can provide detailed morphological information about the terminal branches of the ulnar nerve. • US may be considered as a first-line approach in suspected distal ulnar nerve neuropathies.

Hand size affects branching of the deep ulnar nerve and deep palmar arch

PURPOSE

Understanding the anatomy of the deep neurovascular structures of the hand is essential in surgical planning. There is a lack of literature regarding hand size and its influence in branching variation and the distances between branches of various neurovascular structures. Our study quantifies the variation in branching distances of the deep ulnar nerve and deep palmar arch branches.

METHODS

Twenty-five fresh-frozen cadaveric hands were dissected. Each branch of the deep ulnar nerve and deep palmar arch was identified. The distance from the most distal portion of the pisiform to the proximal aspect of the branch was measured. The relationship between the length of the third metacarpal and the distance of each branch from the pisiform was examined.

RESULTS

There was no relationship between branching differences in the deep ulnar nerve and the length of the third metacarpal. There was a significant association between the length of the third metacarpal and the second, third, and fourth branches of the deep palmar arch (p < 0.05).

CONCLUSIONS

Our study found a significant association between the branching distances of the second, third, and fourth branches of the deep palmar arch and hand size as measured by the length of the third metacarpal.

Ultrasound-guided ethyl alcohol injection to the deep branch of the ulnar nerve to relieve hand spasticity in stroke patients: A case series

Hand spasticity with a flexor pattern is a common problem affecting stroke patients and can result in pain, contractures, esthetic concerns, skin maceration, and overall loss of function. Poststroke (≥6 months) hemiparetic adult patients having a Modified Ashworth Scale (MAS) score of ≥1 for metacarpophalangeal flexion and thumb adduction spasticity were selected to receive an ultrasound-guided 20% ethyl alcohol block performed perineurally at the level of the deep branch of the ulnar nerve. Their MAS scores were evaluated pretreatment at 1 month and the change in MAS scores was assessed using Wilcoxon’s test. The threshold for statistical significance was set at p < 0.05. The mean MAS score for the flexor muscles of the 5 MCP joints and for thumb adduction was reduced from 3.3 ± 0.5 at pretreatment to 0.9 ± 0.5 at 1 month after the injection for the 10 patients. One month after the injection, the MAS scores were significantly reduced compared with those at pretreatment (p < 0.001), without complications. These are encouraging results showing that ultrasound-guided alcohol blocks of the deep branch of the ulnar nerve are safe and can help chronic stroke patients with metacarpophalangeal flexion and thumb adduction spasticity at 1 month.

Differentiation of ulnar neuropathy at the wrist due to ganglion cyst from ulnar neuropathy at the elbow

OBJECTIVE

Here, we aimed to describe the clinical, electrodiagnostic (EDx) and ultrasonographic (US) findings in a series of patients with ulnar neuropathy at the wrist (UNW) due to compression by a ganglion cyst. We also sought features that differentiate UNW from ulnar neuropathy at the elbow (UNE).

METHODS

We reviewed electronic medical records of consecutive patients with UNW caused by ganglion cysts. We compared their clinical, EDx and US findings to findings in our previously reported prospective series of UNE patients.

RESULTS

We identified 10 patients with UNW caused by ganglion cyst compression, who all presented with intrinsic hand muscle weakness and atrophy. Compared to 175 UNE patients they less often complained of paresthesia (60% vs. 98%) and presented less sensory loss in the palm (30% vs. 96%) and little finger (50% vs. 95%). They more often had distal ulnar motor latency recorded from the abductor digiti minimi (ADM)>3.6ms (80% vs. 30%), and denervation activity on needle EMG in the first dorsal interosseous (FDI) compared to ADM (100% vs. 60%). Only 20% of our UNW patients had ulnar nerve swelling at the site of compression on US.

CONCLUSION

UNW potentially caused by ganglion cyst should be suspected in patients presenting with intrinsic hand muscle atrophy and weakness, particularly in cases with normal sensation, increased distal ulnar motor latency recorded from ADM and more severe neuropathic changes in FDI compared to ADM muscle.

Ultrasound of the ulnar-palmar region of the wrist: normal anatomy and anatomic variations

Ultrasound (US) assessment of the wrist is frequently used for the evaluation of carpal tunnel due to high frequency of local compression of the median nerve (MN), but the ulnar-palmar wrist region (UPWR) has received limited attention in the medical literature. The possibilities of US in the assessment of UPWR are therefore likely underestimated by sonologists. This review article is focused on the US assessment of the normal anatomy and anatomic variations of the UPWR. The anatomy of this region of the wrist is complex and less studied than the radial side. In an effort to simplify it and to present it didactically, we have divided this region in three parts on the basis of osseous landmarks. Our review indicates sonography is effective in identifying the UPWR and related disorders, and is thus a valuable tool for ensuring appropriate management of a variety of disorders.

Reliability of focal identification of motor fascicles of the ulnar nerve proximal to the wrist: an anatomical study

We investigated whether motor fascicles of the ulnar nerve can be reliably identified proximal to the wrist. In 17 cadaveric upper limbs, the anterior interosseous nerve was transected at its arborization in the pronator quadratus and transposed to the palmar aspect of the ulnar nerve. The motor fascicular bundle was identified at this level after distinguishing the intraneural epineural involution by microsurgical probing. The motor branch was identified in Guyon's canal and traced retrograde via intraneural dissection to assess accuracy of the original identification. The motor fascicular bundle was found to have been correctly identified in all specimens. We conclude that local anatomic landmarks allow for the motor fascicular group to be correctly identified. Therefore, retrograde, internal dissection of the ulnar nerve is not likely to be required for reliable transfer of anterior interosseous nerve to ulnar nerve motor fascicles.

Electrodiagnostic Findings in 441 Patients with Ulnar Neuropathy - a Retrospective Study

Purpose

Ulnar neuropathy (UN) is the second most common focal neuropathy in the upper extremities. Electrodiagnostic studies (EDx), including nerve conduction study (NCS) and electromyography (EMG), are reliable tools for the diagnosis of ulnar neuropathy. We aimed to retrospectively analyze the medical records of patients diagnosed with ulnar neuropathy in a seven-year period and report our findings.

Patients and methods

In this retrospective study, documents of the patients whose ulnar nerve injury was confirmed through electrodiagnostic study in two departments of Physical Medicine and Rehabilitation were collected and demographic data, subjective complaints of the patient, the cause, and electrodiagnostic findings were extracted from each patient’s file. The following points were specifically evaluated in the electrodiagnostic records; type of injury, location, accompanying injuries, sensory nerve action potentials (SNAP) of the fifth finger, SNAP of dorsal ulnar cutaneous nerve (DUCN), compound muscle action potential (CMAP) of abductor digiti minimi (ADM) muscle, nerve conduction velocity (NCV) across elbow, patterns of muscle involvement, and the severity of insult.

Results

Out of 441 records, 305 (69.2%) were male and 68.1% were non-traumatic. Based on our clinical criteria, the intensity of the injury was mild in most cases. The elbow and forearm were the most involved regions in non-traumatic and traumatic cases respectively. Across elbow nerve conduction velocity showed decreased velocity in 71% of records. In non-traumatic cases, the most affected muscle was ADM (97%) and then FDI (85%).

Conclusion

In focal entrapments such as ulnar neuropathy, electrodiagnostic findings are very helpful in assessing location, severity, and type of injury. If a consensus is achieved for the diagnosis of UN, even retrospective studies can become valuable sources for studying UN.

Use of collision tests to identify physiological differences between the median and ulnar nerves

INTRODUCTION

Median and ulnar nerves are used in comparative electrophysiological studies. We analyzed the conduction values in these hand nerves in healthy volunteers to find any physiological differences between them.

METHODS

We performed standard conduction studies and conduction velocity distribution (CVD) tests with estimation of 3 quartiles in 31 healthy right-handed volunteers (17 women, 14 men) with a mean age of 44.8 ± 15.5 years.

RESULTS

The conduction velocities in all quartiles of CVD tests were statistically faster in the ulnar nerve (P < 0.00001), with no differences in the spread of conduction values and no differences between sides. In the ulnar nerve, CVD velocities in all quartiles were faster in the female group (P < 0.05).

DISCUSSION

The ulnar nerve has more fibers conducting with high velocities than does the median nerve. Electrophysiological comparisons between hand nerves must be performed carefully. Muscle Nerve 59:470-474, 2019.

Bodies for Anatomy Education in Medical Schools: An Overview of the Sources of Cadavers Worldwide

The International Federation of Associations of Anatomists (IFAA) recommended in 2012 that only donated bodies be used for anatomy teaching and research. However, in many countries around the world, anatomists still depend on bodies that do not stem from voluntary donations by the deceased but, rather, are "unclaimed." A broad search of the literature was conducted to produce a baseline overview of the sources of cadavers used for anatomy teaching in undergraduate medical curricula on a global scale. Information from the literature search was supplemented with data from a 2016-2017 survey of selected senior local anatomists. Of 165 countries with medical schools, information was gathered for 71. In 22 (32%) of the 68 countries that use cadavers for anatomy teaching, body donation is the exclusive source of bodies. However, in most other countries, unclaimed bodies remain the main (n = 18; 26%) or exclusive (n = 21; 31%) source. Some countries import cadavers from abroad, mainly from the United States or India. In one country, bodies of executed persons are given to anatomy departments. The heterogeneous geographical distribution of body sources cannot easily be accounted for, but religion, culture, and folk beliefs about what should happen to bodies after death seem to play a role. Implementation of the IFAA recommendations still has a long way to go, but it is encouraging that functioning body donation programs exist on all continents and that there are examples of recent rises in donations and of anatomists initiating new donation programs.

Hypothenar hammer syndrome: caused by a muscle anomaly? A case report with review of the literature

The hypothenar hammer syndrome (HHS) is a rare entity of secondary Raynaud's phenomenon. The blunt hypothenar trauma causes a lesion of the vessel wall with a consecutive thrombosis or aneurysm of the ulnar artery at the Guyon's canal. Different risk factors are discussed such as nicotine abuse, or a muscle anomaly in the Guyon's canal. To date, there are five case reports published about muscle anomalies and HHS. We present a case of a 51-year-old shipbuilder with a unilateral HHS on his right dominant hand with a bilateral muscle anomaly. We successfully treated the patient by resection of the aneurysm without a resection of the atypical muscle.