Detailed Instructions: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
See one example below:
Problem: Abstract: Some patients converted from ventricular fibrillation to organized rhythms by defibrillation - trained ambulance technicians(EMT - Ds) will refibrillate before hospital arrival.The authors analyzed 271 cases of ventricular fibrillation managed by EMT - Ds working without paramedic back - up.Of 111 patients initially converted to organized rhythms, 19(17 % ) refibrillated, 11(58 % ) of whom were reconverted to perfusing rhythms, including nine of 11(82 % ) who had spontaneous pulses prior to refibrillation.Among patients initially converted to organized rhythms, hospital admission rates were lower for patients who refibrillated than for patients who did not(53 % versus 76 % , P = NS), although discharge rates were virtually identical(37 % and 35 % , respectively).Scene - to - hospital transport times were not predictively associated with either the frequency of refibrillation or patient outcome.Defibrillation - trained EMTs can effectively manage refibrillation with additional shocks and are not at a significant disadvantage when paramedic back - up is not available.
Solution: Ventricular Fibrillation
Explanation: This term is directly present in the abstract and it is one of the main topic in it. So can be chosen as the medical subject heading.

Problem: Abstract: Thirty-five patients with complete myelopathies secondary to cervical spine fractures from C-4 to C-7 underwent spinal decompressions and fusions between 1975 and 1981. Twenty-five of these patients underwent simultaneous nerve root decompressions, 23 with an accompanying anterior decompression and fusion and 2 with an accompanying posterior fusion. Substantial recovery of nerve root function occurred in 15 of these patients. A posterior reduction and fusion without nerve root decompression was performed in each of the remaining 10 patients. None of these patients demonstrated a significant improvement neurologically. Operation for nerve root decompression is indicated in selected victims of spinal cord injury.
Solution:
Cervical Vertebrae