2nd Erlangen Interdisciplinary Course for Microscopic and Endoscopic Surgery of the Anterior and Lateral Skull Base

2nd Erlangen Interdisciplinary Course for Microscopic and Endoscopic Surgery of the Anterior and Lateral Skull Base


International course designed for residents in ENT and Neurosurgery as well as more advanced surgeons looking for recent developments in their field of expertise


-> Anterior skull base: Endoscopic/open transfacial approaches to the anterior skull base; Endoscopic/open surgery of the orbita; Cavernous sinus surgery; Pituitary surgery
-> Lateral skull base: Mastoidectomy; Petrosectomy; Translabyrinthine/retrosigmoid/middle fossa approach;
-> Management of complications; Skull base reconstruction, Oncologic therapy concepts

Course Organisation:

Kopf- und Halschirurgie
Director: Prof. Dr. med. Heinrich Iro

Neurochirurgische Klinik
Director: Prof. Dr. med. Michael Buchfelder

Institut für Funktionelle und Klinische Anatomie
Associate Director: Prof. Dr. Lars Bräuer

Anterior percutaneous endoscopic cervical discectomy

Anterior percutaneous endoscopic cervical discectomy

Since the early 2000s, increasingly practical PECD techniques have been introduced because of advancements in working channel endoscope and surgical instrument technology 1) 2) 3) 4).

Anterior percutaneous endoscopic cervical discectomy (PECD) is an effective minimally invasive surgery for soft cervical disc herniation in properly selected cases 5) 6).

The PECD prototype is fluoroscopically guided percutaneous cervical disc decompression without endoscopic visualization, such as automated nucleotomy 7) 8).

Randomized controlled trials

Ahn et al. compared the surgical results of PECD and ACDF. Data from patients treated with single-level PECD (n = 51) or ACDF (n = 64) were analyzed. Patients were prospectively entered into the clinical database and their records were retrospectively reviewed. Perioperative data and clinical outcomes were evaluated using the visual analogue scale (VAS), Neck Disability Index (NDI), and modified Macnab criteriaVAS and NDI results significantly improved in both groups. The rates of excellent or good results were 88.24% and 90.63% in the PECD and ACDF group, respectively. The revision rates were 3.92% and 1.56% in the PECD and ACDF group, respectively. Operative time, hospital stay, and time to return to work were reduced in the PECD group compared to the ACDF group (p < 0.001). The five-year outcomes of PECD were comparable to those of conventional ACDF. PECD provided the typical benefits of minimally invasive surgery and may be an effective alternative for treating soft cervical disc herniation 9).

A total of 103 patients with ACDF or FACD were followed up for two years. In addition to general parameters specific measuring instruments were used. Postoperatively 85.9% of the patients no longer had arm pain, and 10.1% had occasional pain. There were no significant clinical differences between the decompression with or without fusion. The full-endoscopic technique afforded advantages in operation technique, rehabilitation and soft tissue injury. The recorded results show that FACD is a sufficient and safe alternative to conventional procedures when the indication criteria are fulfilled. At the same time, it offers the advantages of a minimally invasive intervention 10).



Chiu, J.C.; Clifford, T.J.; Greenspan, M.; Richley, R.C.; Lohman, G.; Sison, R.B. Percutaneous microdecompressive endoscopic cervical discectomy with laser thermodiskoplasty. Mt. Sinai. J. Med. 2000, 67, 278–282.

Ahn, Y.; Lee, S.H.; Lee, S.C.; Shin, S.W.; Chung, S.E. Factors predicting excellent outcome of percutaneous cervical discectomy: analysis of 111 consecutive cases. Neuroradiology 2004, 46, 378–384.

Ahn, Y.; Lee, S.H.; Shin, S.W. Percutaneous endoscopic cervical discectomy: clinical outcome and radiographic changes. Photomed. Laser Surg. 2005, 23, 362–368.

Ahn, Y.; Lee, S.H.; Chung, S.E.; Park, H.S.; Shin, S.W. Percutaneous endoscopic cervical discectomy for discogenic cervical headache due to soft disc herniation. Neuroradiology 2005, 47, 924–930

Lee, J.H.; Lee, S.H. Clinical and radiographic changes after percutaneous endoscopic cervical discectomy: a long‐term follow‐up. Photomed. Laser. Surg. 2014, 32, 663–668.

Ahn, Y. Percutaneous endoscopic cervical discectomy using working channel endoscopes. Expert. Rev. Med. Devices 2016, 13, 601–610.

Courtheoux, F.; Theron, J. Automated percutaneous nucleotomy in the treatment of cervicobrachial neuralgia due to disc herniation. J. Neuroradiol. 1992, 19, 211–216.

Bonaldi, G.; Minonzio, G.; Belloni, G.; Dorizzi, A.; Fachinetti, P.; Marra, A.; Goddi, A. Percutaneous cervical diskectomy: preliminary experience. Neuroradiology 1994, 36, 483–486.

Ahn Y, Keum HJ, Shin SH. Percutaneous Endoscopic Cervical Discectomy Versus Anterior Cervical Discectomy and Fusion: A Comparative Cohort Study with a Five-Year Follow-Up. J Clin Med. 2020 Jan 29;9(2). pii: E371. doi: 10.3390/jcm9020371. PubMed PMID: 32013206.

Ruetten S, Komp M, Merk H, Godolias G. Full-endoscopic anterior decompression versus conventional anterior decompression and fusion in cervical disc herniations. Int Orthop. 2009 Dec;33(6):1677-82. doi: 10.1007/s00264-008-0684-y. Epub 2008 Nov 18. PubMed PMID: 19015851; PubMed Central PMCID: PMC2899164.

Anterior cervical pseudarthrosis

Anterior cervical pseudarthrosis

Pseudarthrosis may occur with or without supplemental anterior cervical plating.


Difficult to assess because of lack of validated criteria. Estimate: 2–20%. Higher with dowel technique (Cloward) than with the keystone technique of Bailey & Badgley or with the interbody method of Smith-Robinson (10%) or with non-fusion advocated by Hirsch. One criterion: motion>2mm between the tips of the spinous processes on lateral flexion/extension X-rays.

Other criteria that are specific but not sensitive: lucencies around the screws of an anterior plate, toggling of the screws on flexion/extension X-rays.


Not uniformly associated with symptoms or problems. Some patients may have chronic or recurrent neck pain, some may present with radicular symptoms. (NB: when DePalma’s data is analyzed with patients reclassified as failures if the neck and/or arm symptoms persist, the success rate of surgery is lower with pseudarthrosis)


More than 2 mm movement between spinous processes on dynamic (flexion-extension) cervical spine X-rays is recommended as a criterion for pseudarthrosis (Level B Class II); this measurement is unreliable when performed by the treating surgeon (Level C Class II).

Visualization of bone trabeculation across the fusion on static films is a less reliable marker for fusion (Level D Class III) (2D reformatted CT increases the accuracy (Level D Class III)).

see Cervical fusion criteria.


No treatment is required for asymptomatic pseudarthrosis. Options for symptomatic patients include re-resection of the bone graft with repeat fusion (some recommend using autologous bone if allograft was used; a plate may be considered if one was not used previously), cervical corpectomy with fusion, or posterior cervical fusion.

Revision of symptomatic pseudarthrosis should be considered (Level D Class III). Postrior approaches may be associated with higher fusion rates on revision than anterior approaches (Level D Class III).


In 1- and 2-level ACDF with plating involving the same number of fusion levels, there was no statistically significant difference in the pseudarthrosis rate, revision surgery rate, subsidence, and lordosis loss between PEEK cages and structural allograft 1).

Common interbody graft options for anterior cervical discectomy and fusion (ACDF) include structural allograft and polyetheretherketone (PEEK). PEEK has gained popularity due to its radiolucency and its elastic modulus, which is similar to that of bone.

A study sought to compare the rates of pseudarthrosis, a lack of solid bone growth across the disc space, and the need for revision surgery with the use of grafts made of allogeneic bone versus PEEK.

127 cases in which patients had undergone a 1-level ACDF followed by at least 1 year of radiographic follow-up. Data on age, sex, body mass indextobacco use, pseudarthrosis, and the reoperation rate for pseudarthrosis were collected. These data were analyzed by performing a Pearson’s chi-squared test.

Of 127 patients, 56 had received PEEK implants and 71 had received allografts. Forty-six of the PEEK implants (82%) were stand-alone devices. There were no significant differences between the 2 treatment groups with respect to patient age, sex, or body mass index. Twenty-nine (52%) of 56 patients with PEEK implants demonstrated radiographic evidence of pseudarthrosis, compared to 7 (10%) of 71 patients with structural allografts (p < 0.001, OR 9.82; 95% CI 3.836-25.139). Seven patients with PEEK implants required reoperation for pseudarthrosis, compared to 1 patient with an allograft (p = 0.01, OR 10.00; 95% CI 1.192-83.884). There was no significant difference in tobacco use between the PEEK and allograft groups (p = 0.586).

The results of this study demonstrate that the use of PEEK devices in 1-level ACDF is associated with a significantly higher rate of radiographically demonstrated pseudarthrosis and need for revision surgery compared with the use of allografts. Surgeons should be aware of this when deciding on interbody graft options, and reimbursement policies should reflect these discrepancies 2).

The objective of a systematic review done by Kaiser et al. from the Department of Neurological Surgery, Columbia University, New York, USA, was to use evidence-based medicine to identify the best methodology for diagnosis and treatment of anterior pseudarthrosis.

The National Library of Medicine and Cochrane Database were queried using MeSH headings and key words relevant to pseudarthrosis and cervical spine surgery. Abstracts were reviewed, after which studies meeting inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons.

Evaluation for pseudarthrosis is warranted, as there may be an association between clinical outcome and pseudarthrosis. The strength of this association cannot be accurately determined because of the variable incidence of symptomatic and asymptomatic pseudarthroses (Class III). Revision of a symptomatic pseudarthrosis may be considered because arthrodesis is associated with improved clinical outcome (Class III). Both posterior and anterior approaches have proven successful for surgical correction of an anterior pseudarthrosis. Posterior approaches may be associated with higher fusion rates following repair of an anterior pseudarthrosis (Class III).

If suspected, pseudarthrosis should be investigated because there may be an association between arthrodesis and outcome. However, the strength of this association cannot be accurately determined. Anterior and posterior approaches have been successful 3).



Wang M, Chou D, Chang CC, Hirpara A, Liu Y, Chan AK, Pennicooke B, Mummaneni PV. Anterior cervical discectomy and fusion performed using structural allograft or polyetheretherketone: pseudarthrosis and revision surgery rates with minimum 2-year follow-up. J Neurosurg Spine. 2019 Dec 13:1-8. doi: 10.3171/2019.9.SPINE19879. [Epub ahead of print] PubMed PMID: 31835252.

Fivefold higher rate of pseudarthrosis with polyetheretherketone interbody device than with structural allograft used for 1-level anterior cervical discectomy and fusion. J Neurosurg Spine. 2018 Oct 1:1-6. doi: 10.3171/2018.7.SPINE18531. [Epub ahead of print] PubMed PMID: 30485200.

Kaiser MG, Mummaneni PV, Matz PG, Anderson PA, Groff MW, Heary RF, Holly LT, Ryken TC, Choudhri TF, Vresilovic EJ, Resnick DK; Joint Section on Disorders of the Spine and Peripheral Nerves of the American Association of Neurological Surgeons and Congress of Neurological Surgeons. Management of anterior cervical pseudarthrosis. J Neurosurg Spine. 2009 Aug;11(2):228-37. doi: 10.3171/2009.2.SPINE08729. PubMed PMID: 19769502.
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