R. Shane Tubbs

Meckel's diverticulum: A review

Meckels diverticulum is the most prevalent congenital abnormality of the gastrointestinal tract. This anomaly is due to the incomplete obliteration ofthe omphalomesenteric duct during the 7th week of gestation and is classically located 2 feet proximal to the ileocecal valve. Variations of this congenital malformation have been recorded based on location, size, and form. While most of the population may be asymptomatic, clinical manifestation, including gastrointestinal bleed and intestinal obstruction, can emerge. Despite the frequency of Meckels diverticulum, it is commonly misdiagnosed due to its mimicry of appendicitis. This article aimed to review this derailment of embryological development. Clin. Anat. 24:416–422, 2011.

Review of the surgical anatomy of the axillary nerve and the anatomic basis of its iatrogenic and traumatic injury

The axillary nerve is invariably reported to be one of the most commonly injured nerves during surgical procedures of the shoulder, and the importance of protecting it cannot be overemphasized. Many researchers have tried to identify safe regions, but the results vary among published studies. The axillary nerve may also be injured during acute trauma to the shoulder or by chronic repeated trauma as has been described in the quadrilateral space syndrome. The nerve injury may occur together with shoulder dislocation and rotator cuff tear, thus comprising the so-called “unhappy triad” of the shoulder joint. Simple attention to potential variations in the origin and course of the axillary nerve and its relationship to the shoulder capsule and having a precise knowledge of “safe zones” during operations can enhance clinical outcomes. The objective of this review, therefore, is to discuss the surgical anatomy of the axillary nerve and further emphasize the clinical importance of the its injury following shoulder trauma.

Duraplasty or not? An evidence-based review of the pediatric Chiari I malformation

ObjectivesFew studies are available that directly compare dural opening with and without additional intradural maneuvers. Therefore, the current review analyzed the available literature regarding this topic.MethodsAn Ovid MEDLINE search was completed using each of the terms “Chiari malformation,” “syringomyelia,” “syrinx,” “syringohydromyelia” in combination with “child” or “pediatric.” Publications were considered relevant if they reported the results of posterior fossa decompression without dural opening (PFD) to posterior fossa decompression with duraplasty (PFDD). The included studies were divided into three categories based upon the surgical techniques studied. The first group of papers included works that directly compared PFD to PFDD. The second group included studies in which all patients were treated with PFD. The third group included studies in which all patients were treated with PFDD. Three outcome parameters were assessed: (1) improvement of clinical signs/symptoms, (2) syrinx resolution, and (3) scoliosis progression.ResultsAt this time, there is no level I or IIa evidence comparing PFD with PFDD. The notions that PFDD has a lower rate of reoperation and that PFD has a lower rate of cerebrospinal fluid-related complications are both based on IIb/B evidence.ConclusionsProspective randomized trials are necessary for definitive comments regarding the success of PFD and PFDD.

Surgery for extratemporal nonlesional epilepsy in children: a meta-analysis

PurposePrevious small studies have demonstrated that seizure outcomes following surgery for extratemporal lobe epilepsy (ETLE) in children are worse than those for temporal lobe epilepsy. We have conducted a meta-analysis of the available literature to better understand ETLE surgical outcomes in children.MethodsWe searched PubMed (1990–2009) for appropriate studies using the following terms: ETLE, ETLE surgery, ETLE surgery outcome, frontal lobe epilepsy, occipital lobe epilepsy, and parietal lobe epilepsy. Our collected data included patient age at seizure onset and surgery, the cerebral lobe involved with epileptogenesis, MRI findings, predominant seizure semiology, intracranial monitoring use (electrode implantation), epileptic region histopathology, and postoperative seizure outcome. Statistical analysis was performed to determine associations among these variables and postoperative outcome.ResultsNinety-five patients from 17 studies satisfied the inclusion criteria. Pathological findings (p = 0.039) and seizure type (p = 0.025) were significantly associated with outcome: A larger proportion of patients with cortical dysplasia and complex partial seizures experienced better outcomes. Age at surgery (p = 0.073) and the cerebral resection site (p = 0.059) were marginally associated with seizure outcome.ConclusionsThis study confirms previous reports: Surgical outcomes for ETLE epilepsy are significantly worse than those for temporal lobe epilepsy. The reasons for this difference may include the diffuse nature of the pathology involved in ETLE, difficulty in localizing the seizure focus in young children, and involvement of “eloquent” nonresectable cortex in epileptogenesis. Because of the reporting variability among different epilepsy centers, more uniform protocols are necessary for fair evaluation and comparison of outcomes among the different centers.

Treatment and management of the Chiari II malformation: an evidence-based review of the literature

ObjectiveMultiple surgical strategies exist for the management of the symptomatic Chiari II malformation. To date, no comprehensive analysis of this medical literature in an attempt to seek out standards or guidelines has been performed, thus serving as the impetus for this present review.MethodsA computerized search of the database of the National Library of Medicine was performed on the English-language medical literature between 1966 and 2003. Terms searched for included hindbrain hernia, Chiari II, Arnold-Chiari, surgery, decompression, syringomyelia, and CSF shunts. All literature found was reviewed with associated references from these sources. Each piece of literature reviewed was scrutinized and guidelines developed utilizing the methodology used by the Guidelines for the Management of Acute Cervical Spine and Spinal Cord Injuries.ResultsAll data reviewed were deemed to be Class III in nature. No standards or guidelines could be established from the available literature. There is significant debate and variable results in the current neurosurgical literature regarding the evaluation of shunt function vs. Chiari II decompression in patients with symptomatic hindbrain herniation.ConclusionsMulti-institutional prospective randomized trials are needed before any conclusions can be drawn regarding symptomatic Chiari II and its treatment paradigm. Until this time, clinical practice will be based on individual surgeons’ experience, training, and personal beliefs.

Chiari's network: review of the literature

The Chiari network, present in approximately 2% of the population, and is a reticulated network of fibers originating from the Eustachian connecting to different parts of the right atrium. Its presence results from incomplete reabsorption of the right valve of the sinus venosus. Chiari’s network is often clinically insignificant. However, it has been reported to be involved in the pathogenesis of thromboembolic disease, endocarditis, arrhythmias, and entrapment of catheters upon percutaneous intervention. While initially discovered and researched using autopsy dissections, Chiari’s network is often found as an incidental finding on diagnostic imaging studies, thus providing new methods for studying its incidence and clinical significance.

Peripheral facial nerve communications and their clinical implications.

The facial nerve (CN VII) nerve follows a torturous and complex path from its emergence at the pontomedullary junction to its various destinations. It exhibits a highly variable and complicated branching pattern and forms communications with several other cranial nerves. The facial nerve forms most of these neural intercommunications with branches of all three divisions of the trigeminal nerve (CN V), including branches of the auriculotemporal, buccal, mental, lingual, infraorbital, zygomatic, and ophthalmic nerves. Furthermore, CN VII also communicates with branches of the vestibulocochlear nerve (CN VIII), glossopharyngeal nerve (CN IX), and vagus nerve (CN X) as well as with branches of the cervical plexus such as the great auricular, greater, and lesser occipital, and transverse cervical nerves. This review intends to explore the many communications between the facial nerve and other nerves along its course from the brainstem to its peripheral branches on the human face. Such connections may have importance during clinical examination and surgical procedures of the facial nerve. Knowledge of the anatomy of these neural connections may be particularly important in facial reconstructive surgery, neck dissection, and various nerve transfer procedures as well as for understanding the pathophysiology of various cranial, skull base, and neck disorders. Clin. Anat. 24:10–18, 2011.

The Chiari malformations: A review with emphasis on anatomical traits

Hindbrain herniations come in many forms and have been further subdivided as their original descriptions. For cerebellar tonsillar ectopia, they can be divided into two categories, acquired and congenital. Acquired hindbrain herniations are due to increased intracranial pressure caused by certain conditions such as trauma or brain tumor. Although the mechanism for their formation is not clear, congenital hindbrain herniation makes up the majority of these congenital malformations. Furthermore, these malformations are often found to harbor additional anatomical derailments in addition to the hindbrain herniation whether it be the cerebellar tonsils (Chiari I malformation) or the cerebellar vermis (Chiari II malformation). This article reviews these forms of cerebellar ectopia and describes the details of their anomalous anatomy. Moreover, this article compares and contrasts the differing embryological theories found in this literature. Clin. Anat. 28:184–194, 2015.

Piriformis syndrome: implications of anatomical variations, diagnostic techniques, and treatment options

Details of piriformis syndrome, including the proper diagnosis and most effective form of treatment, continue to be controversial. While the cause, diagnosis, and treatment of piriformis syndrome remain elusive, many studies have been conducted to investigate newly developed diagnostic techniques as well as various treatment options for piriformis-induced sciatica. Despite the quantity of literature, few studies have demonstrated statistically significant results that support one form of treatment over another. Thus, despite the evidence supporting the newer treatment methodologies for piriformis syndrome, research should continue. It is important not only to evaluate treatment outcomes based on associated pain relief, but also to investigate the functional and anatomical return that patients experience from these studied treatments in order to fully explore the most effective form of therapy for piriformis syndrome.

Anatomy and landmarks for the superior and middle cluneal nerves: application to posterior iliac crest harvest and entrapment syndromes

OBJECT To date, only scant descriptions of the cluneal nerves are available. As these nerves, and especially the superior group, may be encountered and injured during posterior iliac crest harvest for spinal arthrodesis procedures, the present study was performed to better elucidate their anatomy and to provide anatomical landmarks for their localization. METHODS The superior and middle cluneal nerves were dissected from their origin to termination in 20 cadaveric sides. The distance between the posterior superior iliac spine (PSIS) and superior cluneal nerves at the iliac crest and the distance between this bony prominence and the origin of the middle cluneals were measured. The specific course of each nerve was documented, and the diameter and length of all cluneal nerves were measured. RESULTS Superior and middle cluneal nerves were found on all sides. An intermediate superior cluneal nerve and lateral superior cluneal nerve were not identified on 4 and 5 sides, respectively. The superior cluneal nerves always passed through the psoas major and paraspinal muscles and traveled posterior to the quadratus lumborum. The mean diameters of the superior and middle cluneal nerves were 1.1 and 0.8 mm, respectively. From the PSIS, the superior cluneal branches passed at means of 5, 6.5, and 7.3 cm laterally on the iliac crest. At their origin, the middle cluneal nerves had mean distances of 2 cm superior to the PSIS, 0 cm from the PSIS, and 1.5 cm inferior to the PSIS. In their course, the middle cluneal nerves traversed the paraspinal muscles attaching onto the dorsal sacrum. CONCLUSIONS Knowledge of the cutaneous nerves that cross the posterior aspect of the iliac crest may assist in avoiding their injury during bone harvest. Additionally, an understanding of the anatomical pathway that these nerves take may be useful in decompressive procedures for entrapment syndromes involving the cluneal nerves.