Pariwat Thaisetthawatkul

A controlled study of peripheral neuropathy after bariatric surgery

Background: Although peripheral neuropathy (PN) occurs after bariatric surgery (BS), a causal association has not been established. Objectives: To ascertain whether PN occurs more frequently following BS vs another abdominal surgery, to characterize the clinical patterns of PN, to identify risk factors for PN, and to assess if nerve biopsy provides pathophysiologic insight. Methods: Retrospective review identified patients with PN after BS. The frequency of PN was compared with that of an age- and gender-matched, retrospectively evaluated cohort of obese patients undergoing cholecystectomy. Results: Of 435 patients who had BS, 71 (16%) developed PN. Patients developed PN more often after BS than after cholecystectomy (4/126; 3%) (p < 0.001). The clinical patterns of PN were polyneuropathy (n = 27), mononeuropathy (n = 39), and radiculoplexus neuropathy (n = 5). Risk factors included rate and absolute amount of weight loss, prolonged gastrointestinal symptoms, not attending a nutritional clinic after BS, reduced serum albumin and transferrin after BS, postoperative surgical complications requiring hospitalization, and having jejunoileal bypass. Most risk factors were associated with the polyneuropathy group. Sural nerve biopsies showed prominent axonal degeneration and perivascular inflammation. Conclusions: Peripheral neuropathy (PN) occurs more frequently after bariatric surgery (BS) than after another abdominal surgery. The three clinical patterns of PN after BS are sensory-predominant polyneuropathy, mononeuropathy, and radiculoplexus neuropathy. Malnutrition may be the most important risk factor, and patients should attend nutritional clinics. Inflammation and altered immunity may play a role in the pathogenesis, but further study is needed.

Dispersion of the distal compound muscle action potential as a diagnostic criterion for chronic inflammatory demyelinating polyneuropathy

Objective: To assess distal compound muscle action potential (DCMAP) duration as a diagnostic criterion for chronic inflammatory demyelinating polyneuropathy (CIDP). Background: Current electrodiagnostic criteria for CIDP have high specificity but limited sensitivity. Prolonged DCMAP duration has been reported in acute inflammatory demyelinating polyneuropathy. The authors have compared DCMAP duration in patients with CIDP, diabetic polyneuropathy (DP), ALS, and musculoskeletal pain syndrome (MSP) to determine whether it enhances the sensitivity of electrodiagnostic criteria for CIDP. Methods: Data from 23 CIDP, 34 DP, 34 ALS, and 54 MSP patients were reviewed. The time interval between onset of the first negative peak and return to baseline of the last negative peak of the DCMAP was calculated for each nerve. To distinguish CIDP from DP, ALS, and MSP, optimal cutoff values for DCMAP duration were achieved with receiver-operating characteristic curves. The sensitivity and specificity of these cutoff values were compared with each of four sets of electrodiagnostic criteria for CIDP. Results: Mean DCMAP duration in CIDP was significantly longer than in DP, ALS, and MSP. The sensitivity of existing electrodiagnostic criteria for CIDP ranged between 0.43 and 0.61. Their specificity vs DP or ALS was 0.91 to 1. Using DCMAP duration of ≥9 milliseconds for any of four motor nerves yielded a sensitivity of 0.78 for CIDP and specificity of 0.94 vs DP or ALS. Adding DCMAP duration criteria to any one of the three accepted criteria enhanced their sensitivity with little sacrifice of specificity. Conclusion: Quantitation of DCMAP dispersion shows promise as a sensitive and specific adjunctive electrodiagnostic criterion for CIDP.

Contribution of QSART to the diagnosis of small fiber neuropathy

Introduction: We evaluated incorporation of the quantitative sudomotor axon reflex test (QSART) into the diagnostic criteria for small fiber neuropathy (SFN) as an addition to quantitative sensory testing (QST) and intraepidermal nerve fiber density (IENFD) testing. Methods: One hundred one patients with clinically suspected SFN underwent QSART, QST, and skin biopsy. The diagnostic yield of existing SFN criteria in these patients was compared with criteria incorporating QSART. The new combined diagnostic criteria were evaluated. Results: SFN was diagnosed in 38 of the 101 patients (38%) using current criteria. Addition of QSART existing SFN criteria resulted in an increased diagnostic yield to 67 patients (66%). Applying new SFN criteria requiring abnormality in at least 2 assessments among QSART, QST, and IENFD resulted in a diagnosis of SFN in 57 patients (56%). Conclusion: Assessment of both somatic and peripheral autonomic small nerve fibers enhances diagnostic criteria for SFN. Muscle Nerve 48: 883–888, 2013

Acute inflammatory demyelinating polyneuropathy: contribution of a dispersed distal compound muscle action potential to electrodiagnosis.

Prolonged duration of the distal compound muscle action potential (DCMAP) (“DCMAP dispersion”) is useful in the electrodiagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) with good specificity in distinguishing CIDP from amyotrophic lateral sclerosis (ALS) and diabetic polyneuropathy, but its role in the electrodiagnosis of acute inflammatory demyelinating polyneuropathy (AIDP) is unclear. This study addresses this issue by determining the optimal cutoff for DCMAP duration using receiver operating characteristic (ROC) analysis in 207 motor nerves from 53 clinically defined AIDP patients compared to 148 motor nerves from 55 ALS patients. We also determined whether the presence of DCMAP dispersion improves the sensitivity of four of the most sensitive published sets of electrodiagnostic criteria for AIDP. Using the ROC‐derived optimal DCMAP duration cutoff of 8.5 ms, DCMAP dispersion was found in at least one motor nerve in 66% of subjects with AIDP compared to 9% of subjects with ALS. DCMAP dispersion improved the sensitivity of the four tested criteria sets to 76%–87% from 43%–77%. Moreover, of 13 AIDP patients who met none of the four published criteria sets, 5 (38%) had at least one dispersed DCMAP. These findings indicate that the presence of DCMAP dispersion adds electrodiagnostic sensitivity to the currently published criteria sets, while maintaining reasonably high specificity against a prototypical disorder of the primary motor neuron with axon loss. Muscle Nerve, 2006

Dispersion of the distal compound muscle action potential in chronic inflammatory demyelinating polyneuropathy and carpal tunnel syndrome.

Median neuropathy at the wrist can confound the electrodiagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP), since both conditions can prolong median distal motor latency. Dispersion of the distal CMAP (DCMAP) has recently emerged as a potentially useful adjunct in the electrodiagnosis of CIDP, with good specificity in distinguishing CIDP from certain axon‐loss disorders. However, it is uncertain whether focal compression neuropathies produce dispersion of the DCMAP in a manner similar to CIDP. In this study we compared median DCMAP duration in 27 patients with CIDP and 86 with carpal tunnel syndrome, using 39 patients with non‐neuropathic musculoskeletal pain syndromes as electrophysiologic controls. We found that, in contrast to CIDP, dispersion of the median DCMAP is uncommon, even in advanced carpal tunnel syndrome, being seen in only 8 of 103 (7.8%) hands. Although the pathophysiologic reasons for a differential effect of focal compression‐mediated demyelination and multifocal immune‐mediated demyelination (CIDP) on DCMAP duration are uncertain, our findings suggest that the presence of dispersion of the median DCMAP may prove useful in distinguishing immune‐mediated demyelination from compression neuropathy alone. Muscle Nerve 28: 189–193, 2003

Vasculitic neuropathy associated with minocycline use.

Introduction: Minocycline is an antibiotic used for the treatment of acne. It has been associated with several autoimmune syndromes, including drug-induced lupus, autoimmune hepatitis, and vasculitis. Method and Results: We report a case of a 28-year-old previously healthy woman who developed a left sciatic mononeuropathy 2 weeks after starting minocycline for acne. Magnetic resonance imaging studies supported the localization. A biopsy of the left sural nerve revealed acute nerve large arteriole necrotizing vasculitis. Her condition improved after the withdrawal of minocycline and a course of treatment with methylprednisolone. Conclusion: This case provides further evidence that minocycline may induce a nonsystemic necrotizing vasculitis.

Peripheral nervous system manifestations of lyme borreliosis

Lyme disease is a tick-borne illness that has protean neurologic manifestations involving both the central and peripheral nervous system. The peripheral nervous system manifestations of Lyme borreliosis can be divided chronologically into acute and chronic forms. Within weeks after disease onset, approximately 15% of untreated patients develop an acute Lyme meningoradiculoneuritis with headache, fever, radicular pain, weakness, and sensory loss, often associated with cranial neuropathy, usually facial palsy. Cerebrospinal fluid typically shows lymphocytic pleocytosis, high protein, and normal glucose. Diagnosis is made by recognition of characteristic clinical features with a history of preceding exposure and confirmed by serologic evidence of exposure to B. burgdorferi or by antibody or PCR evidence of cerebrospinal fluid infection. Months to years after onset, rare patients may develop chronic polyradiculoneuropathy presenting with sensory symptoms or radicular pain. Diagnosis is confirmed by a history of exposure, previous systemic or acute neurologic manifestations of Lyme borreliosis, and serologic evidence of infection. Pathology of acute or chronic Lyme radiculoneuropathy reveals axonal degeneration with perivascular mononuclear infiltration. Eradication of the organism can be achieved with 2 to 4 weeks of ceftriaxone for both acute and chronic Lyme neuroborreliosis. Isolated facial palsy without evidence of cerebrospinal fluid infection can be treated with oral antibiotics such as doxycycline. Prognosis after therapy is good, but neurologic recovery is slower for chronic than acute Lyme radiculoneuropathy.

Neuromuscular Complications of Bariatric Surgery

Bariatric surgery is being performed more often to alleviate the symptoms of severe obesity. There are complications to this surgery that need to be understood, however. To help understand the pathophysiology of neuromuscular complications after bariatric surgery, this article reviews the techniques and surgical and metabolic complications of bariatric surgery. Then, neuromuscular complications after the surgery are reviewed.

Postsurgical inflammatory neuropathy: A report of five cases

BACKGROUND Clinical and pathologic descriptions of postsurgical inflammatory neuropathy have been reported but this condition is still under recognized. METHODS We reviewed 5 cases of a biopsy-proven inflammatory neuropathy that occurred within 30 days after surgical procedures. These patients were seen at one center in a 2-year period. RESULTS All patients developed neuropathy symptoms with time delay between the surgery and the neuropathy onset. In all, the symptoms progressed up to the time of evaluation. Electrophysiological studies revealed mononeuropathy or asymmetrical polyneuropathy with active denervation. Nerve biopsies showed ischemic injury and perivascular inflammatory collections in all cases. All patients were treated with intravenous methylprednisolone and four of them showed clinical improvement. The non-responsive patient did not receive immunotherapy until 2 years after neuropathy onset. CONCLUSIONS The report illustrates that focal or asymmetrical neuropathy is typical of postsurgical inflammatory neuropathy and has a favorable outcome after intravenous corticosteroid treatment. The report underscores the importance for considering potentially treatable inflammatory neuropathies in the post-surgical setting.

Autonomic evaluation is independent of somatic evaluation for small fiber neuropathy

BACKGROUND The relationship between the autonomic reflex screening test (ARS) and measures of sensory function and structure (quantitative sensory testing (QST) and intraepidermal nerve fiber density (IENFD)) remains uncertain in patients with distal small fiber neuropathy (SFN). The aim of this study was to evaluate the correlations among a range of autonomic (quantitative sudomotor axon reflex test (QSART), cardiovagal and cardio adrenergic tests and the composite autonomic severity score (CASS)) and somatic sensory measures (QST of vibration, cooling and heat-pain thresholds and IENFD). METHOD 122 patients with clinically suspected sensory neuropathy without motor weakness and with normal nerve conduction studies underwent blinded autonomic reflex screening test (ARS), quantitative sensory testing (QST) and skin biopsy (IENFD) for diagnosis of SFN. The relationship between autonomic and somatic sensory measures was assessed. RESULTS There was no association between autonomic function measures (QSART volume, CASS_QSART, CASS_vagal, CASS_adrenergic or total CASS) and small fiber sensory measures (IENFD, cooling or heat-pain thresholds). Weak correlations were noted among some modalities of QST (vibration and cooling thresholds) and IENFD. DISCUSSION Autonomic and sensory outcomes are independent (complementary) measures of distal SFN, and should where feasible be used concurrently in the evaluation of SFN.