Spinal accessory neuropathy,droopy shoulder,and thoracic outlet syndrome

Droopy shoulder has been proposed as a cause of thoracic outlet syndrome. Two patients developed manifestations of neurovascular compression upon arm abduction, associated with unilateral droopy shoulder and trapezius muscle weakness caused by iatrogenic spinal accessory neuropathies following cervical lymph node biopsies. The first patient developed a cold, numb hand with complete axillary artery occlusion when his arm was abducted to 90 degrees. The second patient complained of paresthesias in digits 4 and 5 of the right hand, worsened by elevation of the arm, with nerve conduction findings of right lower trunk plexopathy (low ulnar and medial antebrachial cutaneous sensory nerve action potentials). Spinal accessory nerve grafting (in the first patient) coupled with shoulder strengthening physical exercises in both patients resulted in gradual improvement of symptoms in 2 years. These two cases demonstrate that unilateral droopy shoulder secondary to trapezius muscle weakness may cause compression of the thoracic outlet structures.     

Usefulness of antegrade selective cerebral perfusion during aortic arch operations

BACKGROUND: To evaluate the safety and usefulness of antegrade selective cerebral perfusion (SCP) during arch aneurysm or aortic dissection operations. METHODS: Between January 1986 and December 2001, 330 patients underwent aortic arch repair using SCP. Operations were performed with the aid of hypothermic extracorporeal circulation, SCP, and systemic circulatory arrest in most cases. In all, 89 patients (27%) were operated on for acute aortic dissection, 77 (23%) for chronic aortic dissection, and 164 (50%) for degenerative aneurysm. Total arch replacement using a branched graft was performed in 288 patients (94%). Mean SCP time was 86.2 +/- 28.5 minutes. RESULTS: The overall in-hospital mortality rate was 11.2% (falling to 3.2% in the 124 patients operated on between 1997 and 2001). Independent determinants of hospital mortality were pump time, renal/mesenteric ischemia, chronic renal failure, increasing age, period of operation, and nonuse of four-branched arch graft. The overall postoperative incidences of temporary and permanent neurologic dysfunction were 4.2% and 2.4%, respectively. There was no significant correlation between SCP time and in-hospital mortality or neurologic outcome. CONCLUSIONS: Selective cerebral perfusion is a reliable technique for cerebral protection and it facilitates complex and time-consuming total arch replacement.     

Impact of an aggressive surgical approach on surgical outcome in type A aortic dissection

BACKGROUND: To evaluate the impact of an aggressive surgical approach on early and late outcome in type A aortic dissection. METHODS: From 1983 to 2001, 240 patients underwent operation for acute (n = 138) and chronic (n = 102) type A aortic dissection. The extent of distal aortic resection included the ascending aorta in 39 (16%) patients, hemiarch (HAR) in 47 (20%), and total arch (TAR) in 154 (64%), including 19 patients who also had their descending aorta replaced (DAR). RESULTS: The in-hospital mortality did not differ between TAR with or without DAR and other more conservative techniques (12.3% versus 16.3%). Actuarial survival at 10 years including in-hospital mortality was 72.4% +/- 3.3% and freedom from reoperation was 77.2% +/- 3.6% for all patients: neither was influenced by the extent of distal aortic resection or acuity of aortic dissection. Multivariate analysis revealed younger age and failure to resect the intimal tear to be independent determinants for late reoperation. However, in contrast to 22 patients who had more conservative operations, none of the patients with TAR required reoperation on the aortic arch through a sternotomy incision. CONCLUSIONS: An aggressive surgical approach did not adversely influence early and late survival following type A aortic dissection; it reduced the necessity of late reoperation and facilitated distal aortic reoperation.     

Electrodiagnostic approach to the patient with suspected mononeuropathy of the lower extremity

Lower extremity mononeuropathies are less common than those affecting the upper limb. Yet, they are often challenging and more difficult to diagnose. The electrodiagnostic (EDX) studies play a pivotal role in diagnosis. Well planned and executed studies are very useful, although limiting factors such as age, foot swelling or prior lumbar spine surgery may hinder making a definite diagnosis. In this section, the author emphasizes the EDX studies of most lower extremity mononeuropathies and discusses, briefly, their anatomical and clinical aspects.     

Modeling and characterization of a nanoliter drug-delivery MEMS micropump with circular bossed membrane

A MEMS (micro-electro-mechanical systems) micropump with circular bossed membrane designed for nanoliter drug delivery is characterized in this article. A quasistatic model under consideration of low operating frequency is used to characterize this micropump. The mathematical model is an ordinary differential equation that describes the behavior of the micropump by including its key components of bossed membrane and inlet/outlet microvalves. Characterizations of bossed membrane and microvalves are carried out separately in the finite element analysis ANSYS package. The stroke volume of the membrane is calculated within the range that the linear deflection theory is valid. Analysis of the microvalve is a challenging task in microfluidics because it is a coupled field (solid-fluid coupling) problem. To solve the structural (solid) or fluid part separately is impractical in characterizing drug-delivery micropumps. Based on sequential weak solid-fluid coupling in ANSYS/FLOTRAN, the flow rates across the inlet and outlet microvalves are analyzed and simulated. Because the quasistatic equation contains several nonlinear terms, closed-form analytical solution for this equation is impossible; thus MATLAB is used to solve it numerically. The transient flow rate of the micropump is obtained by substituting the pressure in microchamber into the flow rate function of outlet microvalves. Integration of the function over 1 driving cycle and multiplication by the driving frequency provides the drug-delivery rate of the micropump.     

Adult polyglucosan body disease: a case report of a manifesting heterozygote

A 62-year-old man developed progressive gait instability, bladder dysfunction, proximal weakness, distal sensory loss, and mild cognitive impairment over 6 years. Neurologic examination revealed upper and lower motor neuron dysfunction in the lower extremities, with distal sensory loss. Electrodiagnostic studies, magnetic resonance imaging of the brain, and sural nerve biopsy were consistent with adult polyglucosan body disease. Biochemical and genetic analyses demonstrated reduced glycogen brancher enzyme levels associated with a heterozygous point mutation (Tyr329Ser or Y329S) in the glycogen brancher enzyme gene on chromosome 3. Mutational heterozygosity in the glycogen brancher enzyme gene has not been previously reported as a cause for this rare disease. A review of the clinical presentation, pathogenesis, etiology, and diagnosis of this disease is presented.     

Chronic hepatitis C treatment. Side effects and their management

The current standard of treatment of chronic hepatitis C infection is the combination therapy of pegylated interferon plus ribavirin for 48 weeks for genotype 1 and 4 and 24 weeks for genotype 2 and 3. Side effects such as influenza-like syndrome, gastrointestinal, neuropsychiatric, dermatological and endocrinological symptoms are not uncommon. Laboratory abnormalities such as hematological and biochemical may be frequent. These side effects are compatible with treatment continuation if symptoms are managed carefully. The adverse effects are dose dependent and often reversible. Premature withdrawal rates can be reduced if side effects are identified early. It is, however, pertinent to target treatment to early responders and avoid side effects in patients who have low predictive response to treatment.