We admitted an 83-year-old male from a neurological department, with 2-month persistent symptoms and slowly developing paraparesis. The MRI identified a rheumatoid pannus causing ventral compression at the C1-2 level. Two days after the posterior C1-2 fixation and laminectomy, we performed the ASR surgery without any complications. After the procedure, the patient’s paraparesis gradually resolved itself and he became self-sufficient.
The 62-year-old male presented with moderate tetraparesis, dysphagia, and Bechterew disease in the anamnesis. From the MRI scans we identified a rheumatoid pannus compressing the medulla oblongata. Nine days after the dorsal C1-2 fusion we performed the ASR surgery, during which the anterior arch of the C1, the upper two-thirds of the odontoid process, and the pannus causing the compression were removed. This surgery was completed without complications. The neurological deficit, dysphagia and tetraparesis gradually resolved themselves, and 10 days after the second surgery the patient was discharged to his home.
With the 42-year-old female, the CT and contrast MRI showed the C1 and C2 vertebra’s tumorous infiltration – due to a metastatic cervix squamous cell carcinoma metastasis - which caused the ventral compression of the spinal cord. She had no neurological deficits, only pain in her nape which radiated to the left shoulder. Two days after the occipitocervical – C0-3 dorsal stabilization, we performed the ASR surgery to remove the metastasis and free up the spinal cord. On the fourth day after the second surgery she was discharged to her home with relieved pain.
Patient four – our first patient with the ASR procedure:
The 44-year-old male had a motorcycle accident, and the CT showed that he had suffered an Anderson-D’Alonso type II. odontoid fracture, during which a 17 mm long cortical bone fragment from the process broke off and punctured the dura while causing compression to the medulla oblongata. The MRI scan confirmed liquor-leakage behind the odontoid process and showed injury to the posterior ligamentous complex. The patient was tetraplegic on admission. At the first step, we performed an emergency C1-2 fusion and the removal of the posterior arch of the C1 vertebra to decompress the medulla oblongata. Due to the patient’s instable circulatory system we could not perform the ventral decompressive surgery immediately, but only 7 days later. During this ASR procedure we removed the middle third of the odontoid process, as well as the haematoma and the cortical bone fragment causing the compression. In the course of the operation we also explored the dural injury, and successfully tamponaded and tissue-glued it. The patient is now self-sufficient.
The mean operative time in the cases was 145 minutes. Tracheostomy was not needed in any of the cases. The patients were extubated immediately after the procedure. They spent 12 hours in the intensive care unit for observation and were started on an oral diet within 24 hours. There were no intra- or postoperative complications, and significant neurological improvement presented in every case. The mean follow-up time was 8.25 months (15, 8, 4, 6). The 83-year-old male operated due to the rheumatoid pannus died four months after the surgery in Clostridium difficile sepsis. The other three patients are alive, able to walk and are self-sufficient. During the four surgeries - on average - we operated 94.3 mm deep, measured from the skin incision. This was calculated by averaging the distance measured from the skin surface to the C1 tubercle, the ventral surface of the C2 and the deepest point of the freed-up dura in all four cases (altogether 12 values). The area of decompression measured in the coronal plane was 5.44, 4.84, 4.83 and 3.50 cm2 - 4.65 cm2 in average. We planned the surgeries with the TO method using CT scans. In these cases, the mean length of the surgical channel would have been 89.8 mm - 4.5 mm less than with the MIS ASR. The maximum possible area of decompression, measured in the coronal plane on the CT scans, would have been 7.35, 5.81, 5.61 and 5.44 cm2 - 6.05 cm2 in average. Based on our calculations, we assume that by using the TO approach, we could have decompressed a larger dural surface by an average of 1.40 cm2. We believe that this difference occurs due to the fact that during the MIS ASR surgery - compared to the TO method - the distance between the C1 anterior tubercle and the midline of the corpus of C2 is seen at a more obtuse angle, reducing the possible area of decompression by 1.40 cm2 (Figure 3).