C1-C2 transarticular screw fixation for treatment of C1-C2 instability

C1-C2 instability has traditionally been treated by C1-C2 posterior wiring and bone grafting. However, this technique has an incidence of non-union which may exceed 10%. Transarticular screw fixation has developed as a technique of providing increased strength of fixation of C1-C2 arthrodesis, while at the same time avoiding the need for postoperative halo bracing and avoiding the risk of neurological injury associated with the passage of sublaminar wires. We present a retrospective review of 12 patients with C1-C2 instability treated by C1-C2 transarticular screw fixation. Eight patients underwent this procedure as primary treatment, and 4 after a failed Gallie fusion. Five patients had a cruciate ligament rupture, 5 had an odontoid process fracture, 1 had os odontoideum, and 1 had rheumatoid instability. There was no surgical morbidity or mortality and, at a mean follow up of 12.1 +/- 3 months (range 8-14 months), all patients had achieved solid fusion, and all neurological symptoms referable to the instability had resolved. C1-C2 transarticular screw fixation has been shown to be safe and effective and has a number of advantages when compared to traditional posterior wiring techniques. We recommend that this technique be considered as a primary treatment of C1-C2 instability.     

Troublesome Occipital Neuralgia Developed by C1-C2 Harms Construct

Recently, Harms and Melcher modified Goel''s approach, the C1 lateral mass and C2 pedicle screw fixation, and the new technique is currently in favor among neurosurgeons. Comparing to the advantages of Harms construct, the disadvantages were not extensively investigated. We experienced a patient with severe occipital pain developed after the C1 lateral mass screw placement for the traumatic atlantoaxial instability. We reviewed literatures about Harms construct with focus on the occipital neuralgia as a postoperative complication and suggest here technical tips to avoid the troublesome pain.     

Clinical and radiological Comparison of treatment of atlantoaxial instability by posterior C1–C2 transarticular screw fixation or C1 lateral mass-C2 pedicle screw fixation

We compared the clinical and radiological results of posterior atlantoaxial fixation surgery using transarticular screws to those using a polyaxial screw–rod system in 55 patients with symptomatic atlantoaxial instability. Patients underwent posterior C1–C2 fixation: 28 patients (group 1) underwent C1–C2 transarticular screw fixation and 27 patients (group 2) underwent C1 lateral mass–C2 pedicle screw fixation. Patients were followed-up for at least 24 months. The clinical and radiological results were evaluated in the early postoperative period and at 3, 6, 12 and 24 months after surgery. Long-term postoperative stability and bone fusion were examined. After surgery, 93% of patients in group 1 and 96% of patients in group 2 were free of neck pain. The solid fusion rates were 82% for group 1 patients and 96% for group 2 patients at 12 months (p < 0.092). In group 1, three patients showed fibrous union. Four patients had hardware failure due to a screw malposition (one in group 1) and pseudoarthrodesis (two in group 1 and one in group 2). One patient in group 1 had cerebrospinal fluid leakage. One patient in group 2 had occipital neuralgia. One vertebral artery injury occurred during the screw placement in group 1 and another in group 2 during the muscle dissection. C1–C2 transarticular screw fixation and C1 lateral mass–C2 pedicle screw fixation both produced excellent results for stabilization of the atlantoaxial complex, but the radiological outcome tended to be superior in C1 lateral mass–C2 pedicle screw fixation.     

Rheumatoid atlantoaxial instability treated by anterior transarticular C1-C2 fixation. Case report

The authors present a case that demonstrates the usefulness of anterior transarticular screw fixation in the treatment of instability due to rheumatoid arthritis. The surgical technique of this infrequently used procedure is presented. A 35-year-old female patient with medical history significant for rheumatoid arthritis complained of persistent headache and upper neck pain. Examination revealed a decreased range of cervical rotational motion. Magnetic resonance imaging of the cervical spine revealed anterior displacement of C1, destruction of the left lateral atlantoaxial articulation and bony erosion of the C2 vertebral body below the base of the odontoid. Dynamic radiographs showed increased C1-C2 mobility. The authors used a right anterolateral approach to the cervical spine to perform fixation of lateral atlantoaxial articulations by means of titanium cannulated compressive screws. On 4-month follow-up examination, successful C1-C2 stabilization was documented. Despite restriction of neck rotation, the patient reported satisfactory improvement and returned to work.     

An anterior high cervical retropharyngeal approach for C1-C2 intrafacetal fusion and transarticular screw insertion

Craniovertebral instability is a significant challenge to neurosurgeons. We describe an alternative anterior high cervical retropharyngeal approach for C1-C2 intrafacetal fusion and transarticular screw insertion. We dissected 10 cadaveric specimens and fixed the atlantoaxial joint with C1-C2 intrafacetal fusion and transarticular screw insertion. We achieved good surgical exposure and fixation in all cadavers with this technique. The anterior high cervical retropharyngeal approach for C1-C2 intrafacetal fusion and transarticular screw insertion may provide an alternative fusion technique for craniovertebral fusion.     

Modified Brooks posterior wiring technique for three-point C1-C2 arthrodesis

BACKGROUND: The optimal surgical treatment of atlanto-axial instability remains controversial despite the variety of modifications and supplemental techniques currently available. METHODS: We describe a modification of the Brooks posterior wiring technique supplemented with transarticular screws for C1-C2 instability. RESULTS: This method has been implemented in 30 patients in our institution with no radiological failures. CONCLUSIONS: The modification provides several technical advantages and potentially stronger fixation compared to methods currently in use.     

Convergence of trigeminal input with visceral and phrenic inputs on primate C1-C2 spinothalamic tract neurons.

Trigeminal, spinal and vagal afferent fibers overlap in C1-C2 segments. We hypothesized that trigeminal input from the superior sagittal sinus (SSS) can excite C1-C2 spinothalamic tract (STT) neurons receiving thoracic visceral or phrenic inputs. Effects of SSS stimulation were evenly divided among cells responding to each nerve stimulus; magnitude of responses to ipsilateral vagal input was greater in neurons excited by SSS input. Somatic fields of 80% of neurons responding to SSS stimulation included face areas innervated by the trigeminal nerve, whereas somatic fields of 89% of neurons unaffected by SSS stimulation were located only on areas innervated by cervical spinal nerves. Results are consistent with the idea that pain referred to trigeminal areas could originate in thoracic organs.     

Occipital neuralgia: A neurosurgical perspective

Occipital neuralgia typically arises in the setting of nerve compression by fibrosis, surrounding anatomic structures, or osseous pathology, such as bone spurs or hypertrophic atlanto-epistropic ligament. It generally presents as paroxysmal bouts of sharp pain in the sensory distribution of the first three occipital nerves. Due to the long course of the greater occipital nerve (GON), and its peculiar anatomy, and location in a mobile region of the neck, it is unsurprising that the GON is at high risk for compression. Little is known how to diagnose or treat this neuropathic pain syndrome. The objective of this paper is to isolate the etiology involved, and treat this condition promptly. After all nonoperative efforts are exhausted, surgical transection of the nerve is the treatment of choice in these cases. An isolated C2 neurectomy or ganglionectomy is performed for an optimal pain relief. C1-2 instrumented fusion can be considered if, extensive facet arthropathy with instability is identified. Authors review the spectrum of treatment options for this debilitating condition, and discuss the case example of a patient who required conversion to a C1-C2 instrumented fusion following C2 ganglionectomy due to an underlying extensive degenerative disease and intraoperative findings suggestive of atlantoaxial instability.     

Routine sectioning of the C2 nerve root and ganglion for C1 lateral mass screw placement in children: surgical and functional outcomes

Purpose

Adult studies have shown that sectioning the C2 nerve root and ganglion may facilitate placement of C1 lateral mass screws and lead to decreased operative time and blood loss. We report the functional outcomes and complications following routine sectioning of the C2 nerve root and ganglion, which have not been reported in pediatric patients.

Methods

Fifteen consecutive pediatric patients underwent C1 lateral mass screw insertion and bilateral C2 nerve root and ganglion sectioning. Clinical and radiographic assessments were performed at follow-up. Numbness in the C2 distribution and/or occipital neuralgia, operative times, estimated blood loss (EBL), length of stay (LOS), and complications were recorded.

Results

Average follow-up time was 35.7 months. Overall mean operative time was 250.5 min, LOS was 8.46 days, and EBL was 337 cc. When considering only atlantoaxial fusions, mean operative time was 180.7 min and EBL was 97.1 cc. There were no intraoperative complications, and no patient reported new onset occipital neuralgia or numbness in the C2 distribution that would interfere with daily living. Of the patients, 93 % achieved Lenke fusion grade A; one achieved Lenke fusion grade B.

Conclusions

Routine C2 nerve root sectioning and ganglionectomy enhanced surgical exposure of the C1 lateral mass and C1–2 facet joint, potentially maximizing fusion rate and minimizing intraoperative complications. This technique may yield favorable operative times, EBL, and LOS in children undergoing C1 lateral mass screw insertion without negatively affecting functional outcome.     

Resultados de la fijación transarticular C1-C2 en una serie de 20 pacientes

ObjectiveC1-C2 transarticular fixation is an increasingly used surgical method of treating atlantoaxial instability. When properly performed, it can safely provide fusion rates near 100%, but techniques of fixation in this region allow only a small margin of error. We here report the results of C1-C2 transarticular fixation in a series of 20 patients in which different procedures were selected according to the presenting disorder in each case.MethodsThe study group included 9 men and 11 women with a mean age of 48 years (range 17 to 68 years). The causes of instabilities were rheumatoid arthritis in nine patients, type II and III Hangman's fracture of traumatic origin in nine (in association with other lesions in three cases), pseudoarthrosis after type II odontoid fracture in one, and type III complex Cl fracture in a patient with ankylosing spondylitis. Preoperative assessment included flexion and extension plain radiographs and computed tomography (CT) and magnetic resonance imaging (MRI) scans. Operations included transarticular screw fixation in all cases; in patients with rheumatoid arthritis it was associated with sublaminar fixation and bone grafting following Sonntag's technique in all but two cases. Postoperative results were evaluated in relation to the biomechanical stability and fusion was studied by flexion and extension radiographs and CT scans. Pain relief in patients with rheumatoid arthritis patients was assessed using a 0–10 visual analogic scale (V.A.S.).ResultsIn the traumatic group, a consolidation of the fracture and radiologic stability was achieved in all cases. In patients with rheumatoid arthritis, pain improved in all but not the neurological deficit, and in all cases a C1-C2 biomechanical stability was reached despite interlaminar graft resorption in two (25%) cases. With respect to complications, a lesión of the vertebral artery occurred in one case, deviation of the screw in two cases, and breakage of the screw without clinical repercussion in two other cases.ConclusionC1-C2 transarticular screw fixation was a useful technique to achieve satisfacory biomechanical stability in patients with atlatoaxial instability of both inflammatory and traumatic origin with a low rate of complications.     

Modified C1 lateral mass screw insertion using a threaded K-wire. A technical note

Instrumented fixation of the C1-C2 motion segment is a standard surgical technique to stabilise that spinal segment. Instability at C1-C2 can arise from a number of conditions. Fixation of the C1 lateral mass usually involves dissection and exposure of the C2 nerve root and the posterior wall of the C2 lateral mass which can result in significant bleeding from the venous plexus. Whilst image guidance is increasing in accessibility, there are few public hospitals in Australia that have access to this technology. The authors describe their technique for insertion of a C1 lateral mass screw over a threaded K-wire to avoid extensive dissection of the C2 nerve root, reducing the risk of significant haemorrhage from the epidural venous plexus during the procedure. A retrospective analysis was undertaken on 18 consecutive patients who underwent C1-C2 instrumented fixation using this technique. Indications for C1-C2 instrumented fixation included traumatic injury (10 patients), failure of non-operative management of odontoid fractures (5 patients), pathological fractures of C2 (2 patients) and inflammatory conditions (1 patient). All patients underwent successful C1-C2 stabilisation using this technique. Blood loss did not exceed 400mls in any patient. There were no vertebral artery injuries and no patient experienced a neurological deterioration. The authors propose that their technique for insertion of a C1 lateral mass screw over a threaded K-wire is safe and effective with a low risk of neurological or vertebral artery injury. The technique may be considered as a slight modification of the Harm’s procedure to reduce disturbance of the adjacent venous plexus and thereby reduction in intraoperative bleeding and operative time.     

Posterior percutaneous transarticular stand-alone screw instrumentation of C1-C2 with endoscopic assistance: A report of two cases

We present two cases of minimally invasive posterior transarticular screw fixation of C1-C2. The points for screw insertion were visualized by endoscopy via the instrumental port. A patient with a type III odontoid fracture with subluxation underwent a minimally invasive posterior stand-alone transarticular screw fixation. Despite the application of compression screws, for technical reasons, only minimal compression on the anterior third of the C1-C2 lateral joint was achieved. However, complete fracture fusion was achieved with stable fibrous C1-C2 fusion 2.5 years postoperatively. A second patient with a chronic type II odontoid fracture underwent percutaneous C1-C2 fixation by the same method. After 2 years, fracture fusion and C1-C2 lateral mass ankylosis were achieved. The use of a tubular retractor and endoscopy in stand-alone screw fixation of C1-C2 allows direct visualization of the screw entry point and decreases surgical trauma. This procedure might be an alternative to other methods of transarticular instrumentation.     

Total ipsilateral C7 root neurotization to the upper trunk for isolated C5-C6 avulsion in obstetrical brachial plexus palsy: a preliminary technical report

Background

C5-C6 root avulsion in obstetrical brachial plexus palsy (OBPP) is a rare injury with poor prognosis usually associated with breech delivery. The treatment is challenging and requires high microsurgical skills. The triple nerve transfer (spinal accessory nerve, ulnar fascicles, and triceps long or lateral head branch) represents the gold standard treatment. The total ipsilateral C7 nerve root neurotization is a promising technique, which has never been described in OBPP.

Objective

The total ipsilateral C7 nerve root is used as a neurotizer transferred to the upper trunk as an alternative method to other intra- or extra-plexual reconstruction techniques.

Methods

During brachial plexus surgical exploration, an intraoperative neurostimulation was performed to confirm the integrity of C7 and the lesion of C5 and C6. The entire C7 nerve root and the upper trunk are cut. The C7 root was transferred to the upper trunk with a fibrin sealant.

Result

This technique was easily performed with a single approach and avoided intercalated nerve grafts. The C7 nerve root provided a large number of nerve fibers with an adequate diameter to be transferred to the upper trunk. We illustrated this technique with a typical case of a child at 8 years of follow-up.

Conclusion

The total ipsilateral transfer of the C7 root to the upper trunk is a viable alternative procedure for newborns with C5-C6 avulsion.     

Surgical approach to C1-C2 nerve sheath tumors

BACKGROUND: C1 and C2 nerve sheath tumors (NST) are unique in presentation, relationship to neighbouring structures and surgical approaches when compared to their counterparts in other regions of the spine. AIM: The strategies involved in the surgery for C1-C2 NST are discussed SETTING AND DESIGN: Retrospective study. METHODS: 21 patients with C1 (n=6) and C2 (n=15) NST were operated based on their position with respect to the cord i.e. anterior (4), anterolateral (10), posterolateral (5), and posterior (2). The tumors had extra- and intradural components in 20 patients; while in one, the tumor was purely intradural. The operative approaches included the extreme lateral transcondylar approach (3); laminectomy with partial facetectomy (5); laminectomy (11); and, suboccipital craniectomy and laminectomy (2). RESULTS: Total excision was performed in 13 patients; while in 7, a partial extraspinal component, and in 1, a small intradural component were left, in situ. Thirteen patients showed improvement by one or more grades in the Harsh myelopathy score; 2 patients with normal power had significant decrease in spasticity; while 5 maintained their grade. One poor-grade patient succumbed to septicemia. CONCLUSIONS: C1-C2 NST may have exuberant growth due to the capacious spinal canal and the absence of a "true" intervertebral foramen at this level. Surgical approaches are determined by its relationship to the cord. A "T incision" on the dura, the partial drilling of the facets, sectioning of the denticulate ligament, rotating the operating table 15 to 30 degrees, and at times sectioning the posterior nerve roots are all useful adjuncts for facilitating access.     

Posterior C1 lateral mass and C2 pedicle screw internal fixation for atlantoaxial instability

From January 1999 to May 2005, 25 patients (15 males and 10 females; age range, 18–70 years; mean, 42 years) who demonstrated clinical and radiographic evidence of atlantoaxial instability underwent C1 lateral mass and C2 pedicle screw internal fixation with or without fusion at our Orthopedic Unit. The cause of instability was: 13 patients, traumatic fracture; three patients, rheumatoid arthritis; two patients, rotatory subluxation; two patients, congenital malformation; five patients, failed previous surgery. A mean follow-up of 16 months was obtained (range, 4–48 months). Mean operative time was 107 minutes (range, 80–141 minutes). No patient received a blood transfusion. No patient experienced worsening neurological function related to the procedure postoperatively or at follow-up. No other postoperative complication was observed. All patients were relieved from axial pain. Screw placement and reduction were achieved satisfactorily in all patients. Each patient showed evidence of solid fusion after 12 months by plain radiography and dynamic films. During follow-up, no complications were observed related to the bone graft or the screw rod. We suggest that C1 lateral mass and C2 pedicle screw internal fixation is a reliable method to repair atlantoaxial instability.     

Pain referral patterns of the C1 to C3 nerves: Implications for headache disorders

The cervical nerves may play a significant role in primary headache disorders. We reviewed the patterns of pain evoked by stimulation of the first 3 cervical nerves (C1–C3) in 10 patients with chronic occipital pain, 6 of whom also had migraine. Stimulation at the C1 level evoked periorbital and frontal pain in 6 of 6 patients with migraine but evoked occipital or cervical pain in those without migraine. C2 and C3 stimulation resulted in occipital or cervical pain in all patients. The C1 nerve may have an important sensory function in headache disorders that have orbital and frontal pain as a prominent feature. Ann Neurol 2013;74:145–148     

Unilateral C1 Lateral Mass and C2 Pedicle Screw Fixation for Atlantoaxial Instability in Rheumatoid Arthritis Patients: Comparison with the Bilateral Method

Objective

Bilateral C1 lateral mass and C2 pedicle screw fixation (C1LM-C2P) is an ideal technique for correcting atlantoaxial instability (AAI). However, the inevitable situation of vertebral artery injury or unfavorable bone structure may necessitate the use of unilateral C1LM-C2P. This study compares the fusion rates of the C1 lateral mass and C2 pedicle screw in the unilateral and bilateral methods.

Methods

Over five years, C1LM-C2P was performed in 25 patients with AAI in our institute. Preoperative studies including cervical X-ray, three-dimensional computed tomography (CT), CT angiogram, and magnetic resonance imaging were performed. To evaluate bony fusion, measurements of the atlanto-dental interval (ADI) and CT scans were performed in the preoperative period, immediate postoperative period, and postoperatively at 1, 3, 6, and 12 months.

Results

Unilateral C1LM-C2P was performed in 11 patients (44%). The need to perform unilateral C1LM-C2P was due to anomalous course of the vertebral artery in eight patients (73%) and severe degenerative arthritis in three patients (27%). The mean ADI in the bilateral group was 2.09 mm in the immediate postoperative period and 1.75 mm in 12-months postoperatively. The mean ADI in the unilateral group was 1.82 mm in the immediate postoperative period and 1.91 mm in 12-months postoperatively. Comparison of ADI measurements showed no significant differences in either group (p=0.893), and the fusion rate was 100% in both groups.

Conclusion

Although bilateral C1LM-C2P is effective for AAI from a biomechanical perspective, unilateral screw fixation is a useful alternative in patients with anatomical variations.     

Activation of α2-adrenergic receptors decreases nerve trauma-induced afferent barrage but not autotomy

Effects of the selective α₂-adrenoceptor agonist, medetomidine, on a compound volley of a tibial nerve stimulation-evoked spinal reflex, pain-induced phrenic motor responses and on postoperative neuropathic pain behavior were studied in rats. Medetomidine (0.3 mg/kg) decreased the amplitude of the compound volley recorded from peroneal nerve in response to tibial stimulation in pentobarbital (40 mg/kg) anesthetized rats. Atipamezole, an α₂-adnenoceptor antagonist (1.5 mg/kg) fully restored the response when given 60 min after the medetomidine administration. Pain-evoked phrenic motor responses were completely inhibited upon combination anesthesia by pentobarbital (40 mg/kg) and medetomidine (0.3 mg/kg) (PB+M) but not upon plain pentobarbital anesthesia (50 or 60 mg/kg) (PB50, PB60). To study the effect of medetomidine on postoperative neuropathic pain behavior (autonomy), transection of sciatic nerve was done under PB+M, PB50 or PB60 anesthesia. No differences between the groups were found in the postoperative pain behavior during eight-week follow up. The results show that activation of α₂-adrenergic receptors by medetomidine under pentobarbital anesthesia mitigates trauma-induced afferent barrage, whereas it does not reduce the subsequent autotomy.     

Descending modulation of thoracic visceroreceptive transmission by C1-C2 spinal neurons

Extracellular potentials of single T3 neurons were recorded in pentobarbital anesthetized male rats. Thoracic esophageal distension (ED, 0.3-0.4 ml, 20 s) and intrapericardial injection of bradykinin (BK, 10(-5) M, 0.2 ml, 1 min) were used as noxious visceral stimuli. Chemical activation of C1-C2 neurons with glutamate pledgets (1 M, 1-3 min) decreased background activity and/or excitatory responses of 26/35 (74%) neurons to ED and 34/44 (77%) neurons to BK. After spinal transection at rostral C1 in five animals, glutamate at C1-C2 still significantly reduced excitatory responses of five neurons to BK. Data showed that intraspinal descending modulation of C1-C2 neurons primarily produced descending inhibition of excitatory responses of thoracic spinal neurons to noxious visceral stimuli.     

A Role for Transmembrane Protein 16C/Slack Impairment in Excitatory Nociceptive Synaptic Plasticity in the Pathogenesis of Remifentanil-induced Hyperalgesia in Rats

Remifentanil is widely used to control intraoperative pain. However, its analgesic effect is limited by the generation of postoperative hyperalgesia. In this study, we investigated whether the impairment of transmembrane protein 16C (TMEM16C)/Slack is required for α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptor (AMPAR) activation in remifentanil-induced postoperative hyperalgesia. Remifentanil anesthesia reduced the paw withdrawal threshold from 2 h to 48 h postoperatively, with a decrease in the expression of TMEM16C and Slack in the dorsal root ganglia (DRG) and spinal cord. Knockdown of TMEM16C in the DRG reduced the expression of Slack and elevated the basal peripheral sensitivity and AMPAR expression and function. Overexpression of TMEM16C in the DRG impaired remifentanil-induced ERK1/2 phosphorylation and behavioral hyperalgesia. AMPAR-mediated current and neuronal excitability were downregulated by TMEM16C overexpression in the spinal cord. Taken together, these findings suggest that TMEM16C/Slack regulation of excitatory synaptic plasticity via GluA1-containing AMPARs is critical in the pathogenesis of remifentanil-induced postoperative hyperalgesia in rats.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12264-021-00652-5.