Three-dimensional soft tissue prediction in orthognathic surgery: a clinical comparison of Dolphin, ProPlan CMF, and probabilistic finite element modelling.

Three-dimensional surgical planning is used widely in orthognathic surgery. Although numerous computer programs exist, the accuracy of soft tissue prediction remains uncertain. The purpose of this study was to compare the prediction accuracy of Dolphin, ProPlan CMF, and a probabilistic finite element method (PFEM). Seven patients (mean age 18years; five female) who had undergone Le Fort I osteotomy with preoperative and 1-year postoperative cone beam computed tomography (CBCT) were included. The three programs were used for soft tissue prediction using planned and postoperative maxillary position, and these were compared to postoperative CBCT. Accurate predictions were obtained with each program, indicated by root mean square distances: RMSDolphin=1.8±0.8mm, RMSProPlan=1.2±0.4mm, and RMSPFEM=1.3±0.4mm. Dolphin utilizes a landmark-based algorithm allowing for patient-specific bone-to-soft tissue ratios, which works well for cephalometric radiographs but has limited three-dimensional accuracy, whilst ProPlan and PFEM provide better three-dimensional predictions with continuous displacements. Patient or population-specific material properties can be defined in PFEM, while no soft tissue parameters are adjustable in ProPlan. Important clinical considerations are the topological differences between predictions due to the three algorithms, the non-negligible influence of the mismatch between planned and postoperative maxillary position, and the learning curve associated with sophisticated programs like PFEM.

Functional outcome of myositis patients: can a low-dose glucocorticoid regimen achieve good functional results?

OBJECTIVE: During the last few years, in an attempt to reduce the side effects of glucocorticoid (GC) therapy, we have been treating polymyositis-dermatomyositis (PM-DM) patients with a lower starting dose of GC than is classically recommended. In order to validate this approach, we performed a functional re-evaluation of these PM-DM patients. METHODS: A comprehensive protocol evaluating muscle strength, muscle function, CK levels, persistence of spontaneous activity on electromyography, disability in daily life activities and degree of dependence was applied in 25 non-cancer-associated biopsy-proven PM-DM patients, 15 of whom had been treated with a high-dose regimen (i.e. > 0.5 mg prednisolone/kg/day) and 10 with a low-dose regimen (i.e. < or = 0.5 mg prednisolone/kg/day). RESULTS: Our results indicate that the functional outcome of PM-DM patients given a low-dose starting regimen of GC does not differ from that observed in patients given higher doses. Interestingly, vertebral fractures were less common in patients treated with lower GC doses. CONCLUSIONS: Although our analysis has certain shortcomings, including the small number of patients investigated and their uncontrolled assignment to a low-dose or a high-dose GC regimen, the results of this retrospective study suggest that a low-dose starting regimen of GC can achieve a good functional outcome in PM-DM patients, with a reduction of treatment-related disability. This approach would be welcome as a step forward should it be validated by a longitudinal study.

The lateral femoral cutaneous nerve: nerve conduction technique.

In 58 subjects without signs or symptoms of peripheral nerve disorders, an antidromic sensory nerve conduction study was performed on the lateral femoral cutaneous nerve. Anatomic dissections were performed on two cadavers to reveal the course of the nerve and to localize the optimal stimulation and recording sites. Mean sensory nerve action potential latency was measured at 1.7 msec (SD = 0.23) with a mean amplitude of 10.5 microV (SD = 4.0). The optimal localization of recording and stimulating surface electrodes and nerve conduction technique procedures are discussed. Reliable electrophysiologic criteria, according to age and body mass index, are obtained.

[Compression neuropathy of the cubital nerve at the elbow]. / La neuropathie du cubital par compression au coude.

Compression neuropathy of the ulnar nerve at the elbow has numerous known etiologies, and the anatomy of the ulnar nerve around the elbow leaves it vulnerable to compression at numerous sites. The compression may be extrinsic such as in occupational neuropathy or in cases of postanesthesia neuropathy. The so-called idiopathic compression may be favored by some anatomic variations. The cubital tunnel retinaculum may be loose, leading to ulnar nerve dislocation or subluxation or tight compression of the nerve during flexion of the elbow. Bulging of the synovium in the floor of the tunnel may be the cause of compression in rheumatoid arthritis, whereas osteophytes may be the cause in degenerative osteoarthritis. Cubitus valgus or instability due to a pseudarthrosis of the lateral epicondyle or to ligamentous injury may stretch the nerve. The choice of a surgical technique must be based on (i) the pathophysiology of chronic nerve compression at the elbow, (ii) an understanding of the etiology of the nerve compression in the particular patient's case, and (iii) the knowledge of the potential technical drawbacks of the various operative procedures. Simple decompression is the first choice in case of minimal compression without instability of the nerve. Decompression of the nerve with a medial epicondylectomy is indicated in case of instability of the nerve and is the first choice in case of pseudarthrosis or malunion of the medial epicondyle. Ulnar nerve transposition is technically the most demanding procedure. Inadequate surgical technique creates new sites of compression.(ABSTRACT TRUNCATED AT 250 WORDS)

Evoked muscular potentials in laryngeal muscles.

Neuromyography is the stimulation of a nerve with recording of the electrically induced muscle activity of the innervated muscle. Reflexmyography is the stimulation of an afferent nerve with recording of the reflex muscular response. In the case of the larynx, the superior laryngeal nerve is stimulated, and a muscle response is picked up in the intrinsic laryngeal muscles. With the use of neuromyography and reflexmyography, it has become possible to test the complex polysynaptic reflex pathways of laryngeal innervation, and to obtain valuable information about the site and the degree of the nerve injury, as well as about the state of nerve regeneration. Further neurophysiological and clinical investigation in the field of supranuclear pathways of phonation seems very promising.

Sciatic neuropathy at the popliteal fossa: clinical, ultrasonographic and computed tomographic diagnosis.

A 22-year-old female had been suffering from sciatica-like pain in the left leg for four years. Clinical findings strongly directed further investigations to the popliteal fossa. Ultrasonography located a hypoechogenic mass in the upper lateral popliteal space. Guided by these data, computerized tomography (CT) with vertical reconstructions made the tentative diagnosis of a common peroneal nerve tumor, which was confirmed at operation. Microscopic examination showed a neurinoma of the mixed neurilemmoma-neurofibroma type. In the presence of atypical features of sciatica, a high index of suspicion seems advisable. Emphasis is laid on the complementary contribution of ultrasonography and CT in this type of ill-defined lower limb pain.

[Loss of digital tissues and carpal canal syndrome. Apropos of 3 cases]. / Pertes de substances digitales et syndrome du canal carpien. A propos de trois observations.

We have observed three cases of carpal tunnel syndrome (CTS) complicated by cutaneous ulcerations and acroosteolysis. Although our first patient had a mild case of CTS, he had a concomitant amphetamine addition. This led to a mania for gnawing away at the digits in the territory of the median nerve. Our other two patients had severe cases of CTS. One suffered from diabetes and the other from primary amyloidosis. Surgical decompression of the median nerve was carried out in these two cases and led to rapid healing of the cutaneous lesions. The latter patients suffered from the entity known in the french literature as carpal tunnel "ulcero-mutilating" (ulcero-osteolytic CTS). This paper discusses possible mechanisms for its pathogenesis. In one of our cases, for example, we were struck by the role played by the patient's behavioral habits whether it be conscious or subconscious in the self-perpetration of the cutaneous and osseous lesions.