and Uwe Spetzger1
Department of Neurosurgery, Klinikum Karlsruhe, Karlsruhe, Baden-Württemberg, Germany
Due to the experiences with cervical spinal surgery for decades, the statistical risks of severe complications caused by an operation have significantly decreased. Nevertheless, the patient has to be informed about these risks, and this information has to be documented in a consent form. In general, the risks for severe complications (injury of the spinal cord or nerve roots or blood vessels as well as the trachea and oesophagus) lie in the field of single-digit percentage or even less than 1 %. The prognosis of remission of a radicular syndrome after surgical decompression is very good. Likewise the results after surgical decompression in cases of spondylotic myelopathy have significantly improved.
9.1 Outcome and Risks of Surgery
The main percentage of patients with cervical disc herniation shows cervicobrachialgia as the leading symptom, often accompanied by sensory disorders of the upper limb. The prognosis in terms of remission of these symptoms after surgery is very good. In cases of motor deficits, the prognosis is best in cases of short history and/or slight pareses.
The daily clinical practice shows that by an operation and the consecutive local decompression, a fast remission of pain is achieved that usually is sustained in the long term. Nevertheless, the patient has to be informed that due to progression of degeneration of one or more cervical levels, it is possible that symptoms reoccur.
For cervical spondylotic myelopathy, the preoperative prevalence of motor deficits of upper and lower limbs as well as sensory deficits of upper and lower limbs is higher than that of other disorders, whereas motor deficits of the lower limbs and sensory deficits of the lower limbs often persist after surgery (Machino et al. 2012). The risk of persisting damage of the spinal cord increases with higher age, smoking and/or vascular risk factors.
For the informed consent about surgery, there are special printed forms that were elaborated together by physicians and patients. These forms explain the surgical strategies and inform about the potential risks of surgery. Both should be discussed with and explained to the patient.
The worst complications during cervical spine surgery are of course injuries of the spinal cord, the main blood vessels, the trachea and the oesophagus as well as dislocations or breakout of implants (Bilbao et al. 2010; Saunders et al. 1998; Vaccaro et al. 1998). Further severe complications are CSF leaks, deep infections, secondary instability at the operated level and a palsy of the laryngeal recurrent nerve with hoarseness and dysphagia.
Implant-related complications can be heterotope ossification and pseudarthrosis at the operated level as well as accelerated adjacent level degeneration after fusion surgeries (Eleraky et al. 1999; Swank et al. 1997). General surgical risks include thrombosis, superficial wound healing disorder and keloid formation. The anaesthesiologist has to inform the patient about risks of anaesthesia.
If the harvesting of an iliac crest bone graft is indicated, the patient has to be informed about potential morbidity at the site of harvesting: haematoma, fracture and nerve injury.
Fehlings et al. (2012) analysed 302 cases that underwent either an anterior, posterior or circumferential procedure for the surgical treatment of cervical spondylotic myelopathy and detected a total complication rate of 15.6 %. The most frequent complications were cardiopulmonary events (3.0 %), dysphagia (3.0 %) and superficial wound healing disorder (2.3 %). A perioperative worsening of myelopathy was observed in 1.3 % of cases. In a follow-up after 2 years, the delayed complication rate was 4.4 %. Multivariate factors that were associated with a higher risk of complications were higher age, long operation time and combined approaches.
The incidence of intraoperative injury of the vertebral artery was quantified by Lunardi et al. (2013) with 0.07 % for all kinds of cervical spine surgeries. In 90 % the injury of the vertebral artery does not have permanent consequences for the patient. In 5.5 % it leads to persisting neurological deficits. Mortality was 4.5 %.
Zhu et al. (2013) found a significantly higher reoperation rate for anterior procedures (8.57 %) compared to posterior procedures (0.3 %) in a meta-analysis that included eight studies. Nevertheless, this meta-analysis showed a better recovery of myelopathy after anterior surgery than after posterior surgery.
For posterior fusions with lateral mass screws, Heller et al. (1995) found the following complication rates: injury of a nerve root in 0.6 %, injury of the spinal cord in 2.6 % and loosening of screws in 1.3 %.
In case of a radicular injury, the most frequent deficits are found for the C5 nerve root (Chiba et al. 2002; Tsuzuki et al. 1993). In patients with postoperative C5 palsy in half of the cases, a sensory deficit or pain in the C5 dermatome was observed. In the other half of cases, there was a weakness of the biceps muscle besides the weakness of the deltoid muscle (Yonenobu et al. 1991). The general incidence of postoperative C5 paresis is 4.6 % (Sakaura et al. 2003), whereas there are no significant differences between anterior (4.3 %) and posterior approach (4.7 %). A C5 injury is a serious complication for the patient since the deltoid muscle is innervated by this nerve root only. Thus, a C5 injury leads to a total loss of arm abduction which is a severe handicap in everyday life. Other muscles show only a partial weakness after monoradicular injury due to innervation by two or three nerve roots (e. g. the C5 and C6 innervation of the biceps brachii muscle).