Biomedical subjects

R Shane Tubbs

Publications and source records attributed to R Shane Tubbs.

At least 109 records · Page 6Linked to original sources

PubMed2005

Anatomic landmarks for nerves of the neck: a vade mecum for neurosurgeons.

Anatomic landmarks are often quite useful in localizing structures within the human body, especially in the surgical realm. We have reviewed the medical literature and multiple texts of surgery and anatomy and culled together many anatomic landmarks regarding important nerves of the neck. This region is complicated by formidable anatomy, and a single collection of the relationships of the nerves in this region is lacking in the literature. It is our hope that this collection will serve to assist the surgeon who operates in this region of the body.

Humans↗

PubMed2005

The triangle of the vertebral artery.

OBJECTIVE: Neurosurgical procedures such as proximal brachial plexus repair, scalenotomy, and direct isolation of the proximal vertebral artery require a good working knowledge of the triangle of the vertebral artery. This deep triangle of the neck is bound by the subclavian artery and the anterior scalene and longus cervicis muscles. In addition to the vertebral artery, many important structures are found in this area, such as the ganglionated sympathetic chain and certain cervical spinal nerves. METHODS: Twenty formalin-fixed cadavers were used for this study. Dissection of this triangle was performed, and measurements were made not only of parts of its borders, but also distances from these borders to neurologically important structures within its confines, such as the C8 spinal nerve. RESULTS: In all specimens, the middle scalene muscle was noted to form part of the posterior wall of the triangle. The mean height of the triangle was found to be 3.2 cm, and the mean width of its base was 1.3 cm. We observed that the C8 spinal nerve had a mean distance of 1.2 cm inferior to the apex of the triangle and that the C7 spinal nerve was found inside the triangle in 5% of sides. If the phrenic nerve entered the triangle, it was never found more than 6 mm medial to the anterior scalene muscle. The vertebral artery always traveled intimately along the lateral border of the longus cervicis muscle, and its lateral edge ranged 5 to 8 mm medial to the medial edge of the anterior scalene muscle. CONCLUSION: The C7 spinal nerve was observed in the triangle of the vertebral artery. In addition, the posterior border of the triangle of the vertebral artery was clearly defined in this study, and the middle scalene muscle could be used as a landmark. These data, coupled with our quantitation of parts and structures within the triangle, may assist neurosurgeons who operate on this area of the neck.

Aged↗

PubMed2005

Polymerase chain reaction for the rapid detection of cerebrospinal fluid shunt or ventriculostomy infections.

OBJECTIVE: Infection after cerebrospinal fluid (CSF) shunts or ventriculostomies is a common complication associated with significant morbidity and mortality. Polymerase chain reaction (PCR) is a powerful molecular technique that allows rapid and precise amplification of bacterial deoxyribonucleic acid (DNA) and has proven a powerful tool in the detection of a wide variety of clinically important infectious diseases. We analyzed specimens of CSF derived from ventriculoperitoneal shunts or external ventricular drains by using both conventional cultures and PCR and report herein our preliminary results. METHODS: We selected 86 CSF samples from adult patients who underwent either shunt tap or routine surveillance cultures of their ventriculostomy. These specimens were chosen from a larger group of 300 specimens that were routinely collected (many serially) in our clinical practice. They were chosen because clinical suspicion of infection was increased because of either patient signs and symptoms (fever, stiff neck, lethargy, worsening neurological examination) or preliminary laboratory analysis of CSF data (increased white blood cell count, increased protein level, decreased glucose). We considered this subgroup optimal to efficiently initiate our investigation of the correlation of PCR and culture results. CSF was increased by using standard culture techniques and by using PCR. Samples of CSF that were to undergo PCR had DNA extracted, purified, and amplified for 16S rRNA using primers 16S-Forward and 16S-Reverse of conserved sequence regions of all bacteria. DNA was PCR-amplified for 30 cycles. One microliter of the first PCR product was subjected to nested PCR using primers specific for gram-positive and gram-negative bacteria. Samples were also subjected to PCR amplification for specific detection of Propionibacterium acnes, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus using specific primers for 16S rRNA Propionibacterium, nuclease gene of Staphylococcus, and Mec gene of methicillin-resistant Staphylococcus aureus. RESULTS: For 18 of 86 specimens (21%), both the culture and PCR were positive. For 30 of 86 specimens (35%), both the PCR and culture results were negative. For 42 of 86 specimens (49%), cultures were negative and PCR was positive. There were no positive culture results with negative PCR results. Most negative culture/positive PCR cases occurred after prolonged intravenous antibiotics. Of the 56 PCR-positive specimens, 30 were positive for Propionibacterium acnes, whereas 40 were positive for Staphylococcus aureus. Of the Staphylococcus aureus-positive specimens, two were positive for methicillin resistant-Staphylococcus aureus. Among the 56 PCR-positive specimens, 30 were positive for both Propionibacterium acnes and Staphylococcus aureus; gram-negative organisms were not detected by any method in these specimens. CONCLUSION: These preliminary data suggest that PCR is a highly sensitive, rapid, and potentially promising modality for the detection and treatment of CSF shunt ventriculostomy infection.

Adult↗

PubMed2005

Vagus nerve stimulation for induced spinal cord seizures: insights into seizure cessation.

OBJECT: Vagus nerve stimulation is known to decrease the frequency, duration, and intensity of some types of intracranial seizures in both humans and animals. Although many theories abound concerning the mechanism for this action, the true cause remains speculative. To potentially elucidate a pathway in which vagus nerve stimulation aborts seizure activity, seizures were initiated not in the cerebral cortex but in the spinal cord and then vagus nerve stimulation was performed. METHODS: Ten pigs were anesthetized and placed in the lateral position, and a small laminectomy was performed in the lumbar region. Topical penicillin, a known epileptogenic drug to the cerebral cortex and spinal cord, was applied to the dorsal surface of the exposed cord. With the exception of two animals that were used as controls, once seizure activity was discernible via motor convulsion or increased electrical activity the left vagus nerve, which had been previously isolated in the neck, was stimulated. Following multiple stimulations of the vagus nerve and with seizure activity confirmed, the cord was transected in the midthoracic region and vagus nerve stimulation was performed. Vagus nerve stimulation resulted in cessation of spinal cord seizure activity in all (87.5%) but one experimented animal. Transection of the spinal cord superior to the site of seizure induction resulted in the ineffectiveness of vagus nerve stimulation to cause cessation of seizure activity in all study animals. CONCLUSIONS: The effects of vagus nerve stimulation on induced spinal cord seizures involve descending spinal pathways. The authors believe that this experiment is the first to demonstrate that spinal cord neuronal hyperactivity can be suppressed by stimulation of a cranial nerve. These data may aid in the development of alternative mechanisms for electrical stimulation in patients with medically intractable seizures. Further studies are now necessary to isolate which specific tracts, nuclei, and neurotransmitters are involved in this process.

Animals↗

PubMed2005

Referred shoulder pain from ventriculoperitoneal shunts. Report of three cases.

The authors report on three pediatric patients with ventriculoperitoneal (VP) shunts who presented with chronic right shoulder pain. Imaging revealed that the distal peritoneal catheter was positioned between the right hemidiaphragm and liver. Following surgical repositioning of the distal tubing, all patients experienced resolution of their shoulder pain, which has not recurred. Although seemingly rare, referred shoulder pain from a VP shunt should be added to the list of complications seen with this method of cerebrospinal fluid diversion. The clinician who cares for patients with VP shunts may wish to evaluate cases of shoulder pain without obvious neural or musculoskeletal cause by performing imaging of the distal shunt tubing.

Abdominal Cavity↗

PubMed2005

Transient ventriculoperitoneal shunt dysfunction in children with myelodysplasia and urinary bladder infection. Report of three cases.

The authors present three children born with myelomeningocele and hydrocephalus. Each presented with symptoms/signs of ventriculoperitoneal shunt malfunction. All patients at the time of presentation exhibited significant urinary bladder infections and were appropriately treated for their infection. No patient was found to have an underlying shunt infection. All patients without medically threatening symptoms were carefully observed and noted to have resolution of their shunt dysfunction symptoms/signs following treatment of their urinary bladder infections and thus did not undergo a shunt operation. Based on the courses of these patients, we believe that significant urinary bladder infection in patients with myelodysplasia in whom a shunt has been placed may often be enough to bring a subclinical shunt malfunction to clinical attention or even to be the cause of temporary distal peritoneal shunt malabsorption. Although the exact mechanism for this dysfunction is unclear, treatment of the bladder infection may address the symptomatic shunt dysfunction in some patients so as to avoid operative intervention. We emphasize, however, that careful observation of these patients should be performed during hospitalization because they often rely on adequate cerebrospinal fluid diversion. Only patients with mild symptomatology should be observed first as the initial line of treatment.

Adolescent↗

PubMed2005

Self-mutilation in a child with a tethered spinal cord. Case report.

Self-mutilation after deafferentation injuries has rarely been reported in humans. The authors report on a 16-year-old girl who was born with a myelomeningocele. In adolescence it was noted that concurrent with her spinal cord becoming symptomatically tethered she began to self-mutilate her digits. A rare manifestation of the tethered spinal cord may be dysesthesias that led to self-mutilation.

Adolescent↗

PubMed2005

Surgical anatomy of the dorsal scapular nerve.

OBJECT: There is a paucity of literature regarding the surgical anatomy of the dorsal scapular nerve (DSN). The aim of this study was to elucidate the relationship of this nerve to surrounding anatomical structures. METHODS: Ten formalin-fixed human cadavers (20 sides) were dissected, and measurements made between the DSN and related structures. The nerve pierced the middle scalene muscle at a mean distance of 3 cm from its origin from the cervical spine and was more or less centrally located at this exit site. It lay a mean distance of 1.5 cm medial to the vertebral border of the scapula between the serratus posterior superior, posterior scalene, and levator scapulae muscles. It was found to have a mean distance of 2.5 cm medial to the spinal accessory nerve as it traveled on the anterior border of the trapezius muscle. The nerve intertwined the dorsal scapular artery in all specimens and was found along the anterior border of the rhomboid muscles. On 19 sides the DSN originated solely from the C-5 spinal nerve, and on one side it arose from the C-5 and C-6 spinal nerves. CONCLUSIONS: Knowledge of the anatomy of the DSN will aid the surgeon who wishes to explore and decompress this structure.

Accessory Nerve↗

PubMed2005

Surgical anatomy of the axillary nerve within the quadrangular space.

OBJECT: There is a paucity of literature regarding the surgical anatomy of the quadrangular space (QS), which is a potential site of entrapment for the axillary nerve. Muscle hypertrophy of this geometrical area and fascial bands within it have been implicated in compression of the axillary nerve. METHODS: Fifteen human cadavers (30 sides) were dissected for this study. Measurements of the QS and its contents were made. The mean height of this space was 2.5 cm and the mean width 2.5 cm; its mean depth was 1.5 cm. The axillary nerve was always the most superior structure in the space, and in all cases the nerve and artery hugged the surgical neck of the humerus just superior to the origin of the lateral head of the triceps brachii muscle. This arrangement placed the axillary nerve in the upper lateral portion of the QS in all cadaveric specimens. The nerve branched into its muscular components within this space in 10 sides (33%) and posterior to it in 20 sides (66%). The cutaneous component of the axillary nerve branched from the main trunk of the nerve posterior to the QS in all specimens. Fascial bands were found in this space in 27 (90%) of 30 sides. CONCLUSIONS: Knowledge of the anatomy of the QS may aid the surgeon who wishes to explore and decompress the axillary nerve within this geometrical confine.

Aged↗

PubMed2005

Unusual findings during abdominal placement of a ventriculoperitoneal shunt: report of three cases.

The authors present three cases of infants born with myelodysplasia. Each infant underwent closure of a myelomeningocele and within 2 to 4 days placement of a ventriculoperitoneal (VP) shunt. In each case, on opening the peritoneal cavity, the authors observed egress of a dark or creamy dark fluid. None of the patients had a history of abdominal birth trauma. The decision was made to continue the procedures and send samples of the unusual fluids to the laboratory for culture and analysis. The cultures proved to be nondiagnostic and the characteristics of the fluid samples were most consistent with those of blood-tinged chyle. The authors hypothesize that, occasionally, the mechanical tautness that is created with repair of myelomeningoceles is sufficient to rupture small lymphatic vessels and accompanying blood vessels of the abdomen. An alternative hypothesis is that abdominal compression due to closure of the myelomeningocele may temporarily compress the liver, leading to raised intraportal pressures and resulting in weeping of chyle from the gastrointestinal tract. This abnormal fluid accumulation did not lead to chronic ascites, VP shunt infection, or dysfunction at long-term follow-up examination and abdominal visceral function has not been an issue.

Ascitic Fluid↗

PubMed2005

Supraplacode spinal cord transection in paraplegic patients with myelodysplasia and repetitive symptomatic tethered spinal cord.

OBJECT: The authors describe the technique of transecting the spinal cord in children born with myelomeningocele who have undergone multiple detherings and are functionally paraplegic. METHODS: The authors' technique involves identifying the neural placode and sectioning the normal spinal cord just superior to this site. No postoperative complications have been identified in 14 patients undergoing this procedure over an 11-year period. No patient at last follow up was found to have symptoms referable to a tethered spinal cord. The advantage of this procedure is to excise the normally pia-coated cord, which is unlikely to retether compared with the neural placode, which is often covered with scar tissue and does not have a well-formed pial surface--hence, predisposing it to frequent dorsal adhesions. CONCLUSIONS: The authors believe that this technique is of benefit in a small, carefully selected group of myelodysplastic patients with repetitive tethering of the spinal cord.

Adolescent↗

PubMed2005

An unusual presentation of achondroplasia. Case report.

The authors present a case of an adolescent with achondroplasia and symptoms of neurogenic claudication who, interestingly, also presented with intermittent priapism. Both the neurogenic claudication and priapism were relieved following a thoracolumbar laminectomy. To our knowledge, this is the first report of a dwarf with thoracolumbar spinal canal stenosis presenting with priapism.

Achondroplasia↗

PubMed2005

Beckwith-Wiedemann syndrome in a child with Chiari I malformation. Case report.

The authors present the case of a child diagnosed as having Beckwith-Wiedemann syndrome and Chiari I malformation. Hemihypertrophy is associated with Beckwith-Wiedemann syndrome and has been described in conjunction with Chiari I malformation. The authors hypothesize that the hemihypertrophy that may involve the skull base and Chiari I malformation found in their patient are not spurious findings but are pathologically related, perhaps by slight dysmorphologies of the posterior cranial fossa.

Arnold-Chiari Malformation↗

PubMed2005

Anatomical landmarks for the lumbar plexus on the posterior abdominal wall.

OBJECT: Reports describing surgical landmarks with which to identify the branches of the lumbar plexus found on the posterior abdominal wall are lacking in the English-language literature. METHODS: The authors examined 22 sides from six female and five male cadavers. Measurements were made between the branches of the lumbar plexus and various bone landmarks such as the midline vertebral bodies, supracristal plane--a horizontal line connecting the superior-most aspect of the left and right iliac crests approximating the LA-5 vertebrae--and anterior superior iliac spine (ASIS). The mean distances from the midline and as they emerged through or lateral to the psoas major muscle to the subcostal, iliohypogastric, ilioinguinal, lateral femoral cutaneous, genitofemoral, and femoral nerves, were 5.5, 6, 6.5, 6, 4.5, and 4.5 cm, respectively. At a vertical line through the midpoint between the ASIS and the midline, the subcostal, iliohypogastric, and ilioinguinal nerves were superior to the supracristal plane at mean distances of 8, 4, and 5 cm, respectively. Inferior to the supracristal plane and in a vertical line through a midpoint between the ASIS and the midline, the lateral femoral and femoral nerves were found to have mean distances of 5 and 5.5 cm, respectively. The obturator nerve had a mean distance of 3 cm lateral to the midline. Additionally, the lateral femoral cutaneous nerve had a mean distance of 1.5 cm inferomedial to the ASIS. CONCLUSIONS: A good working knowledge of the locations and anatomy of the nerves of the lumbar plexus on the posterior abdominal wall is necessary for the surgeon who operates in this region. The measurements provided herein will aid the surgeon who wishes to expose or avoid these nerves, thus precluding injury.

Abdominal Wall↗

PubMed2005

The filum terminale externum.

OBJECT: The filum terminale externum (FTE) is the extradural component of the filum terminale internum and little attention has been dedicated to this structure in the literature. The authors theorized that the rare intrasacral ependymomas may originate from ependymal cell collections within the FTE. METHODS: To address this hypothesis, the FTE was dissected and analyzed histologically in 15 adult cadavers. None of the specimens was found to harbor ependymal or other glial cell collections. CONCLUSIONS: The authors found previously undescribed smooth-muscle cells within the FTE. Furthermore, histological analysis identified adipose, nerve, bone, and cartilage cells.

Adipose Tissue↗

PubMed2005

Superficial landmarks for the spinal accessory nerve within the posterior cervical triangle.

OBJECT: The spinal accessory nerve (SAN) within the posterior cervical triangle (PCT) is the most commonly iatrogenically injured nerve in the body. Nevertheless, there is a paucity of published information regarding superficial landmarks for the SAN in this region. Additional identifiable landmarks of this nerve may assist the surgeon in identifying it for repair, use of it in peripheral nerve neurotization, or avoiding it as in proximal brachial plexus repair. The present study was undertaken to provide reliable superficial landmarks for the identification of the SAN within the PCT. METHODS: The PCT was dissected in 30 cadaveric sides. Measurements were made between the SAN and surrounding landmarks. The mean distances between the entry site of the SAN into the trapezius and a midpoint of the clavicle, mastoid process, acromion process, and lateral aspect of the sternocleidomastoid (SCM) muscle were 6, 7, 5.5, and 3.5 cm, respectively. The mean distances between the angle of the mandible and the mastoid process and the exit point of the SAN from the posterior border of the SCM muscle were 6 and 5 cm, respectively. The mean width and length of the SAN were 3 and 3.5 cm, respectively. CONCLUSIONS: It is the authors' hope that these data will aid those who may need to locate or avoid the SAN while undertaking surgery in the PCT and thus decrease morbidity that may follow manipulation of this region.

Accessory Nerve↗

PubMed2005

Severe bilateral atrophy of the spinati muscles in a cadaver.

During the routine dissection of a 62-year-old male cadaver, bilateral atrophy of the supra and infraspinatus muscles was observed. The suprascapular nerves, cervical spinal cord and surrounding muscles were found to be normal. We propose that, in the face of normal histology and other normal shoulder girdle muscles and normal nerves, this case represents an instance of Parsonage-Turner syndrome. To our knowledge, this is the first report of bilateral spinati atrophy in a cadaver.

Cadaver↗

PubMed2005

Unilateral agenesis of the facial artery with compensation by a giant transverse facial artery.

During routine dissections carried out in the course of our medical gross anatomy work, an unusual structure was found unilaterally on the left side of an adult male cadaver. Upon investigation, this was determined to be a hugely dilated transverse facial artery. Also noted was the complete absence of the ipsilateral facial artery. To our knowledge, this is the first report of complete agenesis and not simply diminution of the facial artery with compensatory enlargement of the transverse facial artery.

Dilatation, Pathologic↗