RESUMEN
AIM: Absence of the F-wave may represent the inability of spinal motor neurons to be excited after periods of inactivity. Repetitive stimulation in an otherwise immobile patient acts as a voluntary movement therefore allowing for the production of an F-wave in a patient with previously demonstrated absent F-waves. Through this case report, we attempt to highlight that the absence of the F-wave may result from inexcitability of spinal motor neurons after reduced mobilization. CASE: We present the case of a 48-year-old woman who had been hospitalized in an ICU setting for almost one month due to a subarachnoid hemorrhage, pancreatitis, and respiratory failure. An electromyogram and nerve conduction study (NCS) was performed for weakness in all four extremities. On routine NCS, her F-waves were absent, but after repetitive stimulation was performed, her F-waves appeared. DISCUSSION: This may be further evidence that the absence of the F-wave may result from inexcitability of spinal motor neurons after immobilization or reduced mobility rather than true pathology of the peripheral nerve. The ability to recover F-waves after an initial absence could assist in differentiating between inexcitability of the anterior horn cell and proximal nerve conduction block. This case presentation is an attempt to show that repetitive nerve stimulation may prove to be a useful technique to restore F-waves in patients who are unable to voluntarily contract their muscles, which may help exclude certain pathologic processes.
RESUMEN
Diamond-Blackfan anemia is a congenital hypoproliferative anemia known to be associated with diverse physical anomalies affecting the thumb, craniofacial bones, urogenital system, and heart; prematurity; and fetal demise. We report the case of a 16-month-old boy with Diamond-Blackfan anemia noted to have decreased use of his right side since birth. Magnetic resonance imaging demonstrated a large area of encephalomalacia in the left middle cerebral artery territory. Magnetic resonance angiography showed marked attenuation of the left middle cerebral artery, suggesting a remote thromboembolic event. The laboratory results were remarkable for a decreased hemogolobin of 9.5 g/dL and increased platelets of 591,000/microL. He was heterozygous for the methylenetetrahydrofolate reductase gene C677T mutation. An echocardiogram demonstrated a patent foramen ovale versus an atrial septal defect with left to right shunting. Perinatal stroke may be a rare complication of Diamond-Blackfan anemia in the setting of other risk factors.
