Microelectrode recordings in adult mammals have clearly demonstrated that somatosensory cortical maps reorganize following peripheral nerve injuries and functional modifications; however, such reorganization has never been directly demonstrated in humans. Using magnetoencephalography, we have been able to demonstrate the somatotopic organization of the hand area in normal humans with high spatial precision. Somatosensory cortical plasticity was detected in two adults who were studied before and after surgical separation of webbed fingers (syndactyly). The presurgical maps displayed shrunken and nonsomatotopic hand representations. Within weeks following surgery, cortical reorganization occurring over distances of 3-9 mm was evident, correlating with the new functional status of their separated digits. In contrast, no modification of the somatosensory map was observed months following transfer of a neurovascular skin island flap for sensory reconstruction of the thumb in two subjects in whom sensory transfer failed to occur.Understanding the presence, degree, and functional correlations for human cortical plasticity is of major significance for fundamental neuroscience as well as a potential aid in the diagnosis and rehabilitation of patients with peripheral and central nervous system injuries. That cortical maps can undergo reorganization in adult mammals has been demonstrated following a variety of peripheral sensory alterations including nerve transection (1-3), digital amputation (4,5) and syndactyly (6), and behavioral modification (7,8). Direct neurophysiological evidence for human somatosensory cortical plasticity, however, has never been demonstrated (9).Magnetoencephalography (MEG) is a noninvasive functional brain imaging technique that provides information regarding neuronal activity with high temporal and spatial resolution (10-14). Initial studies using MEG (10,12,14) demonstrated the somatotopy of the human somatosensory cortex, and present-day technology allows such functional maps to be defined with millimeter precision (14). We have been investigating the detailed functional organization of the hand area in normal adult humans and in patients with a variety of congenital and traumatic hand abnormalities. We report here evidence of adult human cortical plasticity, occurring over a time period of weeks to months following surgical correction of congenital syndactyly in two adult males. METHODSA 14-and a 37-channel biomagnetic recording system (Biomagnetic Technologies, San Diego) were used. The orientation of the subject's head in relation to the MEG recording probes was calculated using the sensor position indicator (SPI), a system of transmitters located on the dewars and receivers. affixed to a headband on the patient's head. Sensor locations were expressed using a head-based coordinate system whose origin was defined as the point of perpendicular intersection of the line extending from the nasion and the line connecting the penauricular points. The x, y, and z axes were the lines from t...

No abstract

No abstract

No abstract

No abstract

Proximal radial nerve compression occurs infrequently and is diagnosed successfully even less frequently. A large clinical series of patients with proximal radial nerve compression neuropathy was reviewed to determine better the common symptoms, physical findings, and electrodiagnostic findings, and to identify the predictors of better or worse outcome after surgical decompression. Seventy-nine proximal radial compression neuropathies were treated in 71 patients by the same surgeon between 1991 and 2000. The most consistent symptoms were deep aching pain in the forearm, pain radiation to the neck and shoulder, and a "heavy" sensation of the affected arm. The most common physical findings were tenderness over the radial nerve at the supinator muscle level, pain on resisted supination, and the presence of a Tinel sign over the radial forearm. Electrophysiologic studies were of limited value in diagnosis, with 90% of patients having normal findings. On operation, prominent pathology of the posterior interosseous nerve was observed in 36 of 79 limbs (46%). Follow-up ranged from 12 to 86 months (mean, 21 months) with no significant complications or recurrence of symptoms. Of the 79 nerve decompressions, 77% had excellent recovery and 20% were judged to be good. Of 69 patients employed when treated, 60 resumed gainful employment, including 53 who returned to their regular jobs. Proximal radial compression neuropathies are uncommon but present with a basic constellation of symptoms and physical findings, and decompression can provide excellent relief of symptoms.

No abstract

No abstract