Deep Brain Stimulation Modulates Gamma Oscillations and Theta-Gamma Coupling in Treatment Resistant Depression.

BACKGROUND: Deep brain stimulation (DBS) in the subcallosal cingulate gyrus (SCG) is becoming an effective therapeutic option for treatment resistant depression (TRD). OBJECTIVE/HYPOTHESIS: Identifying the neurophysiological mechanisms altered by DBS may lead to more tailored treatment parameters and enhanced efficacy. METHODS: Twenty TRD patients with implanted DBS in the SCG were recruited. Patients participated in three EEG recording sessions, one with DBS ON, one with DBS randomized to ON or OFF, and one with DBS OFF. During each session, subjects performed N-back working memory tasks, namely the 0-back and 3-back. Fourteen subjects with valid EEG were included in the analysis. Changes in frontal gamma oscillations (30-50 Hz) and coupling between theta (4-7 Hz) and gamma oscillations as a result of DBS stimulation were quantified and correlated with depressive symptoms. RESULTS: DBS stimulation resulted in suppression of frontal oscillations in the ON state relative to the OFF state during the N-back tasks. Greatest suppression was demonstrated in beta and gamma oscillations and most pronounced during the 3-back. Suppression of gamma oscillations in the 3-back correlated with a reduction in depressive symptoms. DBS ON relative to OFF in the 3-back also resulted in an increase in theta-gamma coupling that correlated with a reduction in depressive symptoms. CONCLUSION: Suppression of gamma oscillations and increased theta-gamma coupling through DBS is likely mediated by both SCG activation of inhibitory circuits and an enhancement of plasticity in the frontal cortex. Activation of both pathways may explain the therapeutic properties of DBS in TRD.

EEG power asymmetry and functional connectivity as a marker of treatment effectiveness in DBS surgery for depression.

Recently, deep brain stimulation (DBS) has been evaluated as an experimental therapy for treatment-resistant depression. Although there have been encouraging results in open-label trials, about half of the patients fail to achieve meaningful benefit. Although progress has been made in understanding the neurobiology of MDD, the ability to characterize differences in brain dynamics between those who do and do not benefit from DBS is lacking. In this study, we investigated EEG resting-state data recorded from 12 patients that have undergone DBS surgery. Of those, six patients were classified as responders to DBS, defined as an improvement of 50% or more on the 17-item Hamilton Rating Scale for Depression (HAMD-17). We compared hemispheric frontal theta and parietal alpha power asymmetry and synchronization asymmetry between responders and non-responders. Hemispheric power asymmetry showed statistically significant differences between responders and non-responders with healthy controls showing an asymmetry similar to responders but opposite to non-responders. This asymmetry was characterized by an increase in frontal theta in the right hemisphere relative to the left combined with an increase in parietal alpha in the left hemisphere relative to the right in non-responders compared with responders. Hemispheric mean synchronization asymmetry showed a statistically significant difference between responders and non-responders in the theta band, with healthy controls showing an asymmetry similar to responders but opposite to non-responders. This asymmetry resulted from an increase in frontal synchronization in the right hemisphere relative to the left combined with an increase in parietal synchronization in the left hemisphere relative to the right in non-responders compared with responders. Connectivity diagrams revealed long-range differences in frontal/central-parietal connectivity between the two groups in the theta band. This pattern was observed irrespective of whether EEG data were collected with active DBS or with the DBS stimulation turned off, suggesting stable functional and possibly structural modifications that may be attributed to plasticity.

Use of flexible intramedullary nails in pediatric femur fractures.

Flexible intramedullary nails are now routinely used for stabilization of pediatric femur fractures. Few data are available regarding patients' postoperative range of motion, weight-bearing status, activity levels, use of immobilization, and radiographic leg length discrepancy measured via routine scanograms. Patients who underwent placement of flexible intramedullary nails for a pediatric femur fracture at a single institution from 1998 to 2003 were identified retrospectively. Ninety-one patients were identified with 94 femur fractures. The complication rate was 17% for the 94 fractures, with 8 patients requiring an unplanned return to surgery. The complication rate was significantly higher for patients aged 10 years or older (34%) as compared with that for younger patients (9%). Average time to full weight bearing was 10 weeks, time to radiographic union averaged 10.7 weeks, and time to return to preoperative level of activity averaged 4.9 months. Immediate postoperative weight bearing status was nonweight bearing in 57%. Immobilization or support was used postoperatively in 60% of the patients. Postoperatively, patients had minimal loss of range of motion in hip internal and external rotation and knee extension. Hip and knee flexion rapidly improved postoperatively with an average loss of hip flexion of 0 degree by 3 months and an average loss of knee flexion of 4 degrees by 6 months. Postoperatively, limb length discrepancy was greater than 1 cm in 7 patients at 6 months, 11 patients at 12 months, 3 patients at 18 months, and 2 patients at 2 years. Two patients had persistent limb length discrepancy of greater than 2 cm, but only one patient required an epiphysiodesis for his limb length inequality. Although the end results are favorable, complications are relatively frequent, particularly in older children.

Position of the distal fibular fragment in pronation and supination ankle fractures: a CT evaluation.

BACKGROUND: Although classically the fibula has been reported to be in external rotation after supination-external rotation (SER) or pronation-external rotation (PER) ankle fractures, a previous CT study demonstrated that what had traditionally been interpreted as external rotation of the distal fibular fracture fragment is actually internal rotation of the proximal fibular fragment. The purpose of this study was to evaluate a series of CT scans in patients who have suffered type IV SER or PER ankle fractures to assess the rotational deformity of the fibular fragment. MATERIALS AND METHODS: CT scans of the injured and uninjured extremities were performed on 30 extremities which had sustained either SER (21) or PER (9) injuries. The rotational relationship between the tibia and fibula was determined by a measured rotational ratio. A qualitative assessment of the rotational relationship between the tibia and fibula above, at, and below the fracture site at the level of the mortise was also performed. The difference in the ratio (calculated by subtracting the rotation ratio of the normal side from the fracture side) demonstrated whether the fractured fibula is externally or internally rotated compared to the uninjured side. RESULTS: The average rotational ratio difference above the fracture compared to below the fracture for the SER group demonstrated significant external rotation (p < .001). The PER fracture also demonstrated external rotation of the distal fragment compared to the proximal fragment (p = .002). Additionally, qualitative assessment of the relationship demonstrated no obvious change in the rotational relationship in any patient above the fracture site except one where mild internal rotation of the proximal fragment was noted. However, at the level of the mortise, all had a normal talofibular rotational relationship while 24 of 30 had widening of the medial clear space with external rotation clearly evident on 15 of these 24 scans. CONCLUSION: Our study demonstrated that the distal fibular fragment in both SER and PER fractures is externally rotated relative to both the contralateral normal side and compared to the proximal fibular fragment.

Growth arrest of the distal radius following a metaphyseal fracture: case report and review of the literature.

We report a 12-year-old girl who developed growth arrest of the distal radius physis 9 months after sustaining a complete fracture of the distal radial and ulnar metaphysis with no involvement of the physis evident at time of injury. The girl sustained a fracture of the metaphysis of her right distal radius and ulna after a fall. Anterior-posterior, lateral and oblique radiographs at injury, and during subsequent healing show no evidence of the fracture involving the physis. She was treated with closed reduction and casting for 6 weeks and healed uneventfully. She returned 4 month later concerned about distal ulnar prominence. Radiographs revealed a loss of radial tilt and with suspicion of a physeal bar. Magnetic resonance imaging confirmed a physeal bar located in the dorsal radial region. A literature search of the Medline database was used to obtain prior case reports for review purpose. The patient underwent an epiphysiodesis of the distal radius and ulna along with an opening wedge osteotomy and bone grafting of the distal radius to restore radial height and inclination. She healed without complication and with restoration of the normal relationship of the distal radius and ulna. A review of the literature reveals five reported case of distal radial metaphyseal fractures not invloving the physis leading to growth arrest. By comparison, there are 31 reported cases of distal radius physeal arrest following fractures involving the physis. The physician should be aware that common distal radius metaphyseal fractures may rarely lead to growth arrest.