Cubital tunnel syndrome pathophysiology

Cubital tunnel syndrome is the second most common peripheral compression neuropathy. The unique anatomic relationships of the ulnar nerve at the elbow place it at risk for injury. Normally with elbow range of motion, the ulnar nerve is subjected to compression, traction, and frictional forces. As the elbow is flexed the arcuate ligament elongates producing a decrease in canal volume of 55%. Intraneural and extraneural pressures increase and have been shown to exceed 200 mm Hg with elbow flexion and flexor carpi ulnaris contraction. Because the ulnar nerve courses behind the elbow axis of rotation, elbow flexion produces excursion of the nerve proximal and distal to the medial epicondyle. The ulnar nerve also elongates 4.7 to 8 mm with elbow flexion. Cubital tunnel syndrome may develop because of various factors including repetitive elbow motion, prolonged elbow flexion, or direct compression. An understanding of the anatomy and pathophysiology associated with cubital tunnel syndrome will aid in patient evaluation and determination of the appropriate treatment.     

Exertional compartment syndrome of the upper extremity

Exertional compartment syndrome is characterized by intracompartmental pressures that rise transiently following repetitive motion or exercise, thereby producing temporary, reversible ischemia, pain, weakness, and, occasionally, neurologic deficits. The exact cause or pathogenesis remains unclear; a disturbance of microvascular flow caused by elevated intramuscular pressure leads to tissue ischemia, depletion of high-energy phosphate stores, and cellular acidosis. Anatomic contributing factors may include a limited compartment size, increased intracompartmental volume, constricted fascia, loss of compartment elasticity, poor venous return, or increased muscle bulk. The diagnosis is suspected based on history and confirmed with physical examination and intramuscular pressure evaluation before and after exercise (stress test). Differential diagnosis includes claudication or other vascular abnormalities, myositis, tendinitis, periostitis, chronic strains or sprains, stress fracture, other compression or systemic neuropathies, and cardiac abnormalities with angina or referred extremity pain. Initial treatment includes activity modification; refractory symptoms can be managed with elective fasciotomy.     

Causes of upper extremity compartment syndrome

Multiple causes, including various types of trauma, prolonged compression, muscle avulsions, burn, snake bites, high-pressure injection injuries, exercise, infection, bleeding, and intravenous drug infiltration, have been reported to lead to the development of a compartment syndrome in the upper extremity. Awareness of the different causes and risks of compartment syndrome should facilitate early diagnosis and prompt treatment to help avoid the development of serious sequelae such as Volkmann's ischemic contracture. A review of the various reports of upper extremity compartment syndromes and classification systems is presented to assist in the understanding of this condition's development.     

Prosthesis of the upper extremity

In functional impairment of a joint due to pain and (or) limited mobility in which conservative measures are inadequate, an operation may be considered. The principal possibilities are arthrodesis and implantation of an artificial joint. Reasons to opt for a prosthesis are involvement of adjacent articulations (in rheumatoid arthritis) and preservation of mobility which, together with stability, is necessary for good articular function. The principal indications for implantation of an artificial joint in the upper extremity are rheumatoid arthritis and (to a lesser degree) osteoarthritis and posttraumatic impairments. The functional results of prostheses in the shoulder, elbow and wrist are good, but the proportion of complications is relatively large (compared with that in hip and knee prostheses) and follow-up so far has only been short.     

Pathophysiology and treatment of painful diabetic neuropathy of the lower extremity

BACKGROUND: Symptomatic peripheral neuropathy is the most common complication of diabetes mellitus, affecting up to 62% of Americans with diabetes. METHODS: We reviewed the literature using the National Library of Medicine's MEDLINE search service. In total, we reviewed 54 articles. RESULTS: Hyperglycemia leads to increased activity in the polyol pathway in nerve cells; this ultimately results in abnormal nerve function. Numerous pharmacologic agents have been used to treat symptomatic peripheral neuropathy, but all of these drugs can be associated with adverse side effects. Recent work has indicated that subsensory electrical stimulation may be preferred to pharmacotherapy, since it is equally effective and has a more favorable safety profile. CONCLUSION: Although the pathophysiology of diabetic neuropathy is well understood, treatment of the symptoms associated with this condition can be challenging. Additional research is needed to reveal a safe and effective treatment for this debilitating sequela of diabetes mellitus.     

Neurologic evaluation of the upper extremity

Symptoms and disease processes can overlap, and neurologic symptoms of the hand or arm are not necessarily due to local pathology. To combat these difficulties, the authors present a basic review of neuroanatomy, the neurologic examination, the principles of electromyography, and the process of formulation.     

Necrotizing fasciitis and gangrene of the upper extremity

Necrotizing fasciitis is a severe, fulminant infection most commonly encountered in patients with diabetes mellitus, alcohol abuse, and intravenous drug abuse. The infection can spread-unrecognized along fascial planes beneath seemingly normal skin. The relatively benign appearance of the extremity is misleading and often results in delay in diagnosis and increased morbidity or death. Immediate aggressive surgical debridement through extensile incisions in combination with antibiotic therapy is necessary for control of these limb- and life-threatening, soft-tissue infections. Gas gangrene, or clostridial myonecrosis, is encountered commonly in those extremity wounds that involve devitalized or necrotic soft tissues. Clostridial microorganisms are anaerobes that produce local and systemic toxins. Delay in treatment can lead to hemolysis, renal failure, and death. Treatment consists of immediate wound debridement, intravenous antibiotics, and hyperbaric oxygen therapy. Diabetic gangrene typically occurs in those diabetic patients with severe peripheral vascular or renal disease. The infections are usually polymicrobial. Treatment involves broad-spectrum antibiotics and multiple surgical debridements or amputation.     

Soft tissue coverage for the upper extremity

Soft tissue coverage of the upper extremity continues to be a challenging and evolving field. The expeditious and reliable methods of soft tissue coverage currently in use are discussed with reference to their shortcomings and advantages. For soft tissue coverage of fingertip injuries, open treatment or local flaps from the hand remain the mainstay of treatment. For dorsal and volar hand defects, distal axial flaps, such as the groin flap or microvascular tissue transfer, are utilized most commonly. For large defects proximal to the wrist, trunk axial pattern flaps, microvascular transfer, or the radial forearm flap have the greatest utility. Finally, technical points necessary for the success of some of the flaps are discussed.     

Dynamic skeletal fixation in the upper extremity

Recent advances in the understanding of the biomechanics of the elbow and improvement in material designs have revolutionized the ability to treat difficult problems of the proximal interphalangeal and elbow joints. Dynamic skeletal fixation addresses the desire to allow an injured joint to heal, move, and remain stable simultaneously. In the past, such goals were achieved sequentially or in series. It is now possible to perform such tasks in parallel.     

Tire explosion injuries to the upper extremity

The influence of interferon (IFN) coadministered subcutaneously with the biomodulating agent folinic acid on the blood serum levels of 5-formyl-tetrahydrofolic acid (CHO-THFA) and the biotransformation into its main metabolite in the blood 5-methyltetrahydrofolic acid (CH3-THFA) was studied in patients receiving a chemotherapy with 5-fluorouracil. IFN causes a clear decrease of the serum concentrations of CHO-THFA and a statistically significant decrease of CH3-THFA concentrations (P < 0.01). The effect on serum concentrations could be observed in each patient, but in a different order of magnitude. As a consequence, the preadministration of IFN leads to a significant change in the basic pharmacokinetic parameters of both compounds: the mean area under the concentration-time curve is decreased at 27.4% for CHO-THFA (P < 0.025) and at 22.4% for CH3-THFA (P < 0.025), respectively. The total body clearance is elevated at 45.4% for CHO-THFA (P < 0.05) and at 23.4% for CH3-THFA (P < 0.05). The mean volume of distribution is increased by IFN at 38.2% for CHO-THFA (P < 0.025) and at 22.3% for CH3-THFA (P < 0.05). The nearly identical mean residence time in both groups indicates that CHO-THFA elimination is not affected by IFN. But the results prove a certain interaction between IFN and CHO-THFA. IFN accelerates the distribution of CHO-THFA as well as of its main metabolite from the blood into the tissue or activates the biotransformation of CHO-THFA into CH3-THFA inside the cells of the tissue. The extent of biotransformation of CHO-THFA into CH3-THFA, which takes place in the blood, is not influenced by IFN because percentage AUC-ratios CHO-THFA:CH3-THFA were 89.5:10.5% for the control group and 88.8:11.2% for the IFN group.     

Anatomy of the upper extremity muscle compartments

Schizophrenia, a devastating disease characterized by a combination of various types of disturbed behaviors, thoughts, and feelings, may likewise be heterogeneous in etiology. Recent advances in neuroscience and psychopharmacology have suggested a wide array of competing mechanisms that may be involved in schizophrenia, including but not limited to deficits in one or more neurotransmitters and second messenger systems (e.g., dopamine, serotonin, gamma-aminobutyric acid, glutamate, and noradrenaline), neurodevelopmental defects in brain circuitry, and viral infection. Psychiatric genetic studies indicate that schizophrenia is a disorder with multifactorial inheritance. Since cerebral metabolic activity reflects regional brain work for all neurotransmitter systems, imaging metabolism directly with fluorodeoxyglucose and indirectly with blood flow and hemoglobin oxygen saturation can provide information about the functional neuroanatomy of a deficit in individual patients and allow patients to be grouped into more homogeneous subgroups for intensive study. This review summarizes metabolic imaging studies in schizophrenia over the past decade.     

Volkmann's ischemic contracture of the upper extremity

Upper extremity deformity of ischemic contracture usually includes elbow flexion, forearm pronation, wrist flexion, thumb flexion and adduction, digital metacarpophalangeal joint extension, and interphalangeal joint flexion. Treatment of mild contractures consists of either nonoperative management with a comprehensive rehabilitation program (to increase range of motion and strenght) or operative management consisting of infarct excision or tendon lengthening. Treatment of moderate-to-severe contractures consists of release of secondary nerve compression, treatment of contractures (with tendon lengthening or recession), tendon or free-tissue transfers to restore lost function, and/or salvage procedures for the severely contracted or neglected extremity.     

Dislocations of the upper extremity in children

Traumatic dislocations and subluxations of the upper extremity in children have been surveyed. The elbow joint is most commonly dislocated and is dislocated more frequently in children than in adults. Severe neurovascular injury may be associated with dislocation of this joint. The most common subluxation is that of the radial head, secondary to a "pulled elbow." Otherwise dislocations and subluxations of the upper extremity are uncommon in children, apparently because of the relative weakness of the epiphyseal plate. Most of these injuries are the result of predictable indirect forces. Principles of reduction and immobilization are based on the unique anatomic structure of the joint involved and the known anatomic disruption resulting from the trauma.     

Bioconverter for upper extremity rehabilitation

The bioconverter is a simple instrument which uses the output of the Basmajian-Emory myotrainer to activate electrical devices, such as radios, television, etc. It can be used to assist in training by providing an acceptable and/or pleasurable stimulus (such as a radio) as muscle activation improves. The myotrainer contains adjustable sensitivity circuits, and the bioconverter has a pre-set holding circuit of 2, 4, or 6 seconds duration. A case of a deaf and blind patient is presented where the bioconverter is used to activate other sensory (skin) stimuli rather than audio-visual ones. The bioconverter can also be used in relaxation training. In this mode of operation the controlled equipment is on when no EMG is present and is turned off when too high an EMG level exists.     

Computer keyboard force and upper extremity symptoms

This case-control study assessed whether office workers who report more severe levels of musculoskeletal symptoms of the upper extremities demonstrate higher levels of keyforce in comparison to controls with less severe symptoms. Office workers reporting working on computer keyboards for four hours per day were classified as cases or controls based upon a median split on a Composite Symptom Severity score (cases = 23, controls = 25). Keyboard force and keying rate were measured during a 15-minute keyboarding task. Measures of task-related discomfort, muscular fatigue, pain, upper extremity symptoms, psychological distress and force were collected at baseline, post-keyboard task, and recovery. Ratings of perceived effort and task credibility were also obtained. Measures of work demands, perceived job stress, and upper extremity strength and flexibility were also collected. The results indicated group equivalence on reported work demands and upper extremity strength. Cases were more likely to receive a medical diagnosis of upper extremity cumulative trauma disorder, awaken from sleep due to symptoms, report higher levels of pain during work, experience greater impact of pain on function, and report higher workload pressure and lower support. Cases generated significantly higher keyboarding forces than controls, although both groups produced forces well above that required to operate the keyboard (4-5 times activation force). Cases reported higher levels of upper extremity symptoms and discomfort than controls, and these measures were highest after the keyboarding task for both groups. No significant correlation between keyforce and key rate was observed in either group. Results suggest that generation of excessive force while working on a computer keyboard may contribute to the severity of upper extremity symptoms. Clinically, the findings suggest that evaluating how an individual worker performs keyboarding tasks, or his or her workstyle, may be helpful in the management of these symptoms and disorders.     

Rehabilitation following electrical injury to the upper extremity

This review emphasizes two of the difficult problems associated with electrical injury to the hand and forearm. Early wound closure to preserve important vascular, nerve, and tendon structures in the hand must be considered, recognizing the tendency for continued necrosis of tissue in this type of injury. Tissue fibrosis, even in areas of the hand not grossly injured, may develop, progressively compromising function. Five patients are presented to illustrate the early care and rehabilitation of these patients.     

Current indications for reimplantation of the upper extremity

In the last decades there has been a great development in microsurgery that has enabled successful replantation of totally severed parts. Nowadays, the important issue is to decide which segments should be replanted, in order to achieve a good functional result. In this paper we study the indications and contraindications of replantation, based in our experience and we present a review of the recent literature. We consider the following aspects: general condition and age of the patient, mechanism of lesion, amputation level, ischemic time and also economic aspects. We conclude that replantation should be attempted in thumb and multiple digits amputations, in amputations at the palm, wrist and forearm, in single digit amputations distal to the flexor superficialis insertion and in any case in children.     

Anatomy of upper extremity skin flaps

This article reviews some recent applications of time and frequency domain cross-correlation techniques to human motor unit recording. These techniques may be used to examine the pre-synaptic mechanisms involved in control of motoneuron activity during on-going motor tasks in man without the need for imposed and artificial perturbations of the system. In this review we examine, through several examples, areas in which insights have been gained into the basic neurophysiological processes that bring about motoneuron firing in man and illustrate how these processes are affected by central nervous system pathology. We will demonstrate that synchronization and coherence may be revealed between human motor unit discharges and give examples that support the hypothesis that these phenomena are generated by activity in a focused common corticospinal input to spinal motoneurons. Disruption of central motor pathways due to diseases of the nervous system leads to pathophysiological alterations in the activity of these pre-synaptic motoneuron inputs that can be revealed by cross-correlation analysis of motor unit discharges. The significance of these studies and outstanding questions in this field are discussed.     

Social and economic course after amputation of the upper extremity

Scopadulcic acid B (SDB), a tetracyclic diterpenoid isolated from a medicinal plant, Scoparia dulcis L., inhibited the effects of tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in vitro and in vivo; SDB inhibited TPA-enhanced phospholipid synthesis in cultured cells, and also suppressed the promoting effect of TPA on skin tumor formation in mice initiated with 7,12-dimethylbenz[a]anthracene. The potency of SDB proved to be stronger than that of other natural antitumor-promoting terpenoids, such as glycyrrhetinic acid.