Mitchel Muhleman

The clinical anatomy of the inferior vena cava: A review of common congenital anomalies and considerations for clinicians

Anomalies in the course and drainage of the Inferior Vena Cava (IVC) may complicate normal functioning, correct diagnosis, and therapeutic interventions within the abdomen. Development of the IVC occurs during the 4th to 8th week of gestation, and due to its developmental complexity, there are many opportunities for malformations to occur. Although most IVC anomalies are clinically silent and are usually discovered incidentally on abdominal imaging, aberrations may be responsible for formation of thrombosis, back pain, and anomalous circulation of blood to the heart. In this review, we will discuss the most common variations and abnormalities of the IVC, which include the posterior cardinal veins, the subcardinal veins, the supracardinal veins, persistent left IVC, IVC duplication, situs inversus, left retroaortic renal vein, left circumaortic renal collar, scimitar syndrome, and IVC agenesis. For each abnormality outlined above, we aim to discuss relevant embryology and potential clinical significance with regards to presentation, diagnosis, and treatment as is important for radiologists, surgeons, and clinicians in current clinical practice. Clin. Anat. 27:1234–1243, 2014.

Occipital neuralgia: Anatomic considerations

Occipital neuralgia is a debilitating disorder first described in 1821 as recurrent headaches localized in the occipital region. Other symptoms that have been associated with this condition include paroxysmal burning and aching pain in the distribution of the greater, lesser, or third occipital nerves. Several etiologies have been identified in the cause of occipital neuralgia and include, but are not limited to, trauma, fibrositis, myositis, fracture of the atlas, and compression of the C‐2 nerve root, C1‐2 arthrosis syndrome, atlantoaxial lateral mass osteoarthritis, hypertrophic cervical pachymeningitis, cervical cord tumor, Chiari malformation, and neurosyphilis. The management of occipital neuralgia can include conservative approaches and/or surgical interventions. Occipital neuralgia is a multifactorial problem where multiple anatomic areas/structures may be involved with this pathology. A review of these etiologies may provide guidance in better understanding occipital neuralgia. Clin. Anat. 28:101–108, 2015.

The proatlas: a comprehensive review with clinical implications

BackgroundThe proatlas is derived from the fourth occipital sclerotome in human embryos. It usually fuses with the three upper occipital sclerotomes to form the occipital bone. However, this does not always occur. Manifestations of a partial proatlas structure may persist due to failure of fusion.Clinical considerationsThese embryological remnants can induce several symptoms in humans, ranging from mild to severe. On occasion, this structure can go unnoticed until a precipitating traumatic event results in symptoms. Proatlas segmentation abnormalities form bony masses at C1 and the foramen magnum. A number of surgical procedures have been devised to rectify the resulting neural compression and vascular compromise.DiscussionThis paper will discuss the development of the proatlas and the resultant anomalies associated with its failure to merge with the occipital sclerotomes to form the occipital bone. In addition, some consideration of comparative anatomy and surgical techniques will be presented.

One is the loneliest number: A review of the ganglion impar and its relation to pelvic pain syndromes

The ganglion impar is often overlooked as a component of the sympathetic nervous system. Despite its obscurity, this ganglion provides a pathway for neurons by accommodating postganglionic sympathetics, visceral afferents, and somatic fibers traveling to and from the pelvis. Its classic anatomic location as described in the 1720s held up until recently, with the current literature now revealing a great deal of anatomical variability. This variation becomes important when the ganglion impar is used as a treatment target for patients with chronic pelvic pain – its primary clinical implication. The aim of this review was to provide a better understanding of the anatomy of ganglion impar, accounting for variation in size, shape, and location. In addition, the clinical importance and treatment modalities associated with the ganglion impar are outlined. Clin. Anat. 26:855–861, 2013.

Benjamin Alcock (1801-?) and his canal.

Benjamin Alcock (1801–?) was a prominent anatomist from Ireland who is remembered most for his description of the pudendal canal. He was privileged to train under the great Irish anatomist, Abraham Colles. Following his training and several early teaching engagements, he was appointed as the first Professor of Anatomy and Physiology at Queens College, Cork. He became a Fellow of the Royal College of Surgeons in Ireland. After several years of teaching at Queens College, Alcock was forced to resign after a dispute over the Anatomy Act of 1832, during which he conveyed his disapproval of participation in the procurement of corpses for the school. Several years after his resignation, he left for the United States and removed himself from the view of the profession. His anatomical contributions were published in The Cyclopaedia of Anatomy and Physiology. The description he gave of the sheath enclosing the pudendal nerve and internal pudendal vessels is his most famous contribution to the literature. He is remembered eponymously for Alcocks canal. This articles intent is to clearly and concisely depict the life and contribution of Benjamin Alcock. Clin. Anat. 26:662–666, 2013.

The vermiform appendix: A review

New research on the vermiform appendix has shed light on its function. In further understanding the function of the appendix, this information should not negatively impact the clinical judgment in the event of appendicitis. Although the appendix and its pathology have been noted for centuries, it still presents a challenge in the operating room. The most common emergency surgical procedure performed is an appendectomy. Its highly variable position within the abdomen can cause confusion for clinicians. However, improved imaging modalities have heightened the physicians ability to diagnose disease of this organ. This article reviews germane literature regarding the human vermiform appendix. Clin. Anat. 26:833–842, 2013.

A new form of herniation: the Chiari V malformation

The Chiari malformations (CM) were first described by Hans Chiari roughly a century ago. Most of these malformations result in herniation of part of the cerebellum and brain stem into and through the foramen magnum. This herniation may cause impingement on the structures in the foramen magnum and upper part of the spinal canal with possible blockage of cerebral spinal fluid. Symptoms may include headache, neck pain, numbness of the extremities, dysphagia, nausea, and vomiting. Often the severity of the symptoms increases with the severity of the malformation [4]. Chiari malformation can be congenital or acquired. Congenital forms are thought to be caused by structural malformations early in fetal life due to either genetic mutations or nutritional deficits. Within the two different groups of CM, further classifications exist. The types are characterized by their severity of the malformation. Type 0 CM, described by Iskandar et al., represents absence of frank tonsilar herniation but syringomyelia that resolves following posterior fossa decompression [6]. Type I CM is the most common and is characterized by the protrusion of the cerebellar tonsils into the foramen magnum but without the brainstem. Type 1.5 CM has recently been described in a group of children as caudal protrusion of the brain stem and cerebellar tonsils [3]. Type II is the protrusion of both the brain stem and cerebellar vermis into the foramen magnum and is seen most often in patients with myelomeningocele and type III is the type II malformation with the addition of an occipital or high cervical myelomeningocele [4]. Type IV CM is classified when there is incomplete or underdevelopment of the cerebellum and is therefore not a form of hindbrain herniation. Herein, we describe, the first to our knowledge, a patient presenting with herniation of the occipital lobes into the neck.

To cut or not to cut, that is the question: A review of the anatomy, the technique, risks, and benefits of an episiotomy: To Cut or Not to Cut, That is the Question

Childbirth can be a traumatic experience on the female body. Some techniques may be implemented to make the process smoother and decrease the potential lacerations that can occur. Episiotomies have been used by obstetricians and midwives to help make the fetal decent down the vaginal canal less turbulent. A physician must use his best judgment on when it is necessary to make this incision and what form of incision to make. Before making an incision one must understand the female external and internal anatomy and thoroughly comprehend the stages of birth to understand how and what complications can occur. Even though an episiotomy is a minor incision, it is still a surgical incision nonetheless and as with any form of surgery there are both risks and benefits that are to be considered. Nevertheless, episiotomies have proven to help ease births that are complicated by shoulder dystocia, prevent severe lacerations, and decrease the second stage of labor. The following comprehensive review provides a description of the female anatomy, as well as an extensive description of why, when, and how an episiotomy is done. Clin. Anat. 30:362–372, 2017.

Clinical evaluation and surveillance imaging in children with spina bifida aperta and shunt-treated hydrocephalus.

OBJECT Most children with spina bifida aperta have implanted CSF shunts. However, the efficacy of adding surveillance imaging to clinical evaluation during routine follow-up as a means to minimize the hazard of shunt failure has not been thoroughly studied. METHODS A total of 396 clinic visits were made by patients with spina bifida aperta and shunt-treated hydrocephalus in a spina bifida specialty clinic during the calendar years 2008 and 2009 (initial clinic visit). All visits were preceded by a 6-month period during which no shunt evaluation of any kind was performed and were followed by a subsequent visit in the same clinic. At the initial clinic visit, 230 patients were evaluated by a neurosurgeon (clinical evaluation group), and 166 patients underwent previously scheduled surveillance CT scans in addition to clinical evaluation (surveillance imaging group). Subsequent unexpected events, defined as emergency department (ED) visits and caregiver-requested clinic visits, were reviewed. The time to an unexpected event and the likelihood of event occurrence in each of the 2 groups were compared using Cox proportional hazards survival analysis. The outcome and complications of shunt surgeries were also reviewed. RESULTS The clinical characteristics of the 2 groups were similar. In the clinical evaluation group, 2 patients underwent shunt revision based on clinical findings in the initial visit. In the subsequent follow-up period, there were 27 visits to the ED and 25 requested clinic visits that resulted in 12 shunt revisions. In the surveillance imaging group, 11 patients underwent shunt revision based on clinical and imaging findings in the initial visit. In the subsequent follow-up period, there were 15 visits to the ED and 9 requested clinic visits that resulted in 8 shunt revisions. Patients who underwent surveillance imaging on the day of initial clinic visit were less likely to have an unexpected event in the subsequent follow-up period (relative risk 0.579, p = 0.026). The likelihood of needing shunt revision and the morbidity of shunt malfunction was not significantly different between the 2 groups. CONCLUSIONS Surveillance imaging in children with spina bifida aperta and shunted hydrocephalus decreases the likelihood of ED visits and caregiver-requested clinic visits in the follow-up period, but based on this study, its effect on mortality and morbidity related to shunt malfunction was less clear.

Ventriculoperitoneal shunt malfunction from cerebrospinal fluid eosinophilia in children: case-based update

IntroductionMalfunction of cerebrospinal shunts is common and is due to multiple etiologies ranging from obstruction due to infiltrated brain tissue to mechanical disconnection.DiscussionWe review the differential diagnosis and recommended evaluation and treatment for cerebrospinal fluid (CSF) eosinophilia.Illustrative caseWe report a child who, following the use of an antibiotics-impregnated ventricular catheter, developed sterile ventriculoperitoneal shunt malfunction thought to be due to profound CSF eosinophilia. Following removal of the catheter, the eosinophilia spontaneously resolved, and at long-term follow up, the patient has a functioning non-antibiotic impregnated shunt catheter.ConclusionsPatients presenting with signs of shunt malfunction but without signs of CSF infection and with a raised CSF eosinophilia should be suspicious for cellular obstruction of their shunt system, i.e., sterile shunt malfunction.