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Smruti K. Patel and James K. Liu

Neurenteric cysts are rare and benign lesions that consist of ectopic alimentary tissue residing in the central nervous system. They tend to occur most frequently in an intraspinal rather than intracranial location. Intracranial neurenteric cysts are a rare occurrence in the pediatric population. These lesions typically present as unilateral cystic structures in the lower cerebellopontine angle and craniocervical junction. To the authors' knowledge, there have been no reported cases of bilateral localization of intracranial neurenteric cysts. In this report, they present an unusual case of a 10-year-old girl who was found to have bilateral intracranial neurenteric cysts at the pontomedullary junction. The patient was successfully treated with staged, bilateral far-lateral transcondylar resection of the cysts. The authors also provide a brief overview of the literature describing intracranial neurenteric cysts in children.

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Smruti K. Patel, William T. Couldwell, and James K. Liu

Max Brödel is considered the father of modern medical illustration. This report reviews his contributions to neurosurgery as a medical illustrator.

Max Brödel, a young artist from Leipzig, Germany, was hired at Johns Hopkins Hospital in 1894, where he illustrated an operative textbook of gynecology for Howard A. Kelly. Although Brödel did not have any formal medical training, he quickly acquired knowledge of anatomy, pathology, physiology, and surgery. Brödel's extraordinary illustrations were characterized by an aerial perspective that conveyed the surgeon's operative viewpoint and precise surgical anatomy. He masterfully incorporated tissue realism with cross-sectional anatomy to accentuate concepts while maintaining topographical accuracy. Brödel's reputation spread quickly and resulted in collaborations with prominent surgeons, such as Cushing, Halsted, and Dandy. Cushing, who also possessed artistic talent, became a pupil of Brödel and remained a very close friend.

In 1911, Brödel was appointed the director of the Department of Art as Applied to Medicine at Johns Hopkins, the first academic department of its kind in the world. For the next several decades, he trained generations of renowned medical illustrators. Just as Osler, Halsted, and Cushing passed their skills and knowledge to future leaders of medicine and surgery, Brödel did the same for the field of medical illustration. The advancement of neurosurgical education has been greatly facilitated by Max Brödel's artistic contributions. His unique ability to synthesize art and medicine resulted in timeless illustrations that remain indispensable to surgeons. The art produced by his legacy of illustrators continues to flourish in neurosurgical literature today.

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James K. Liu, Smruti K. Patel, Amanda J. Podolski, and Robert W. Jyung

Reconstruction of presigmoid dural defects after resection of acoustic neuromas via the translabyrinthine approach is paramount to prevent postoperative CSF leakage. However, primary dural reapproximation and achieving a watertight closure of the dural defect in this anatomical region are quite difficult. Standard closure techniques after the translabyrinthine approach often involve packing an abdominal fat graft that plugs the dural defect and mastoidectomy cavity. This technique, however, may pose the risk of direct compression of the fat graft on the facial nerve and brainstem. Nonetheless, even with the evolution in dural repair techniques, postoperative CSF leaks can still occur and provide a route for infection and meningitis. In this report, the authors describe a novel dural “sling” reconstruction technique using autologous fascia lata to repair presigmoid dural defects created after translabyrinthine resection of acoustic neuromas. The fascia lata is sewn to the edges of the presigmoid dural defect to create a sling to suspend the fat graft within the mastoidectomy defect. A titanium mesh plate embedded in porous polyethylene is secured over the mastoidectomy defect to apply pressure to the fat graft. In the authors' experience, this has been a successful technique for dural reconstruction after translabyrinthine removal of acoustic neuromas to prevent postoperative CSF leakage. There were no cases of CSF leakage in the first 8 patients treated using this technique. The operative details and preliminary results of this technique are presented.

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David C. Lobb, Smruti K. Patel, Brian S. Pan, and Jesse Skoch

OBJECTIVE

Patients presenting with head shape changes phenotypical for craniosynostosis may have incomplete fusion of the involved sutures. The surgical literature is lacking in appropriate management strategies for these patients. In this paper, the authors evaluate their experience with a novel treatment strategy: suturectomy of only the fused portion followed by helmeting therapy in patients with skull deformity secondary to incomplete suture synostosis.

METHODS

Patients with craniosynostosis with incomplete suture fusion requiring operative intervention between 2018 and 2020 were included for evaluation. Patients were selected for partial suturectomy if the patent portion of the suture had a normal appearance. All patients underwent craniectomy of the involved portion of the synostosed suture. Intraoperative ultrasound was used to reassess the degree of fusion at the time of surgery and incision planning. A 2- to 3-cm strip craniectomy was performed under direct visualization through a single minimal access incision. Postoperative helmeting was utilized for all patients. Demographic and perioperative data were collected, including laser scan data in the form of cranial index (CI) and cranial vault asymmetry (CVA), defined as the difference between two diagonal measurements, from the frontozygomaticus to the opposite eurion.

RESULTS

Four males and 1 female with a mean age of 2.8 months (range 1.1–3.9 months) at presentation were included. All patients had incomplete sagittal synostosis (one patient also had an incomplete left lambdoid synostosis and another had an incomplete left coronal synostosis). The mean age at surgery was 3.5 months (range 2.0–4.7 months) without any major complications. All patients were compliant with postoperative helmeting. The average age at the last follow-up was 12.8 months (range 5.3–23.7 months) with a mean follow-up duration of 9.3 months (range 0.5–19.6 months). Final laser scan evaluations were available for 3 patients and showed an improvement of the CI from an average of 71.3 (range 70–73) to 84.3 (range 82–86). The CVA improved from an average of 9.67 mm (range 2–22 mm) to 1.67 mm (range 1–2 mm).

CONCLUSIONS

Minimally invasive direct excision of the involved portion of fused cranial sutures followed by helmet therapy for phenotypical craniosynostosis is a safe and effective treatment strategy. This technique is suitable for very young patients and appears to offer similar outcomes to complete suturectomy. Further studies are required to see if this approach reduces the deformity severity for patients requiring vault remodeling later in life.

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Smruti K. Patel, Jorge Zamorano-Fernández, Carlie McCoy, and Jesse Skoch

OBJECTIVE

External magnetic forces can have an impact on programmable valve mechanisms and potentially alter the opening pressure. As wearable technology has begun to permeate mainstream living, there is a clear need to provide information regarding safety of these devices for use near a programmable valve (PV). The aim of this study was to evaluate the magnetic fields of reference devices using smartphone-integrated magnetometers and compare the results with published shunt tolerances.

METHODS

Five smartphones from different manufacturers were used to evaluate the magnetic properties of various commonly used (n = 6) and newer-generation (n = 10) devices using measurements generated from the internal smartphone magnetometers. PV tolerance testing using calibrated magnets of varying field strengths was also performed by smartphone magnetometers.

RESULTS

All tested smartphone-integrated magnetometers had a factory sensor saturation point at around 5000 µT or 50 Gauss (G). This is well below the threshold at which a magnet can potentially deprogram a shunt, based on manufacturer reports as well as the authors’ experimental data with a threshold of more than 300 G. While many of the devices did saturate the smartphone sensors at the source, the magnetic flux density of the objects decreases significantly at 2 inches.

CONCLUSIONS

The existence of an upper limit on the magnetometers of all the smartphones used, although well below the published deprogramming threshold for modern programmable valves, does not allow us to give precise recommendations on those devices that saturate the sensor. Based on the authors’ experimental data using smartphone-integrated magnetometers, they concluded that devices that measure < 40 G can be used safely close to a PV.

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Smruti K. Patel, Qasim Husain, Jean Anderson Eloy, William T. Couldwell, and James K. Liu

Developed over a century ago, the transsphenoidal approach to access lesions of the pituitary gland and sella turcica has transformed the field of neurosurgery, largely due to the work of Oskar Hirsch and Harvey Cushing. Furthermore, its use and modification in the early 1900s was perhaps one of Cushing's greatest legacies to skull base surgery. However, Cushing, who had worked relentlessly to improve the transsphenoidal route to the pituitary region, abandoned the approach by 1929 in his pursuit to master transcranial approaches to the suprasellar region. Hirsch and a few other surgeons continued to perform transsphenoidal operations, but they were unable to maintain the popularity of the approach among their peers.

During a time when transsphenoidal surgery was on the brink of extinction, a critical lineage of 3 key surgeons—Norman Dott, Gerard Guiot, and Jules Hardy—would resurrect the art, each working to further improve the procedure. Dott, Cushing's apprentice from 1923 to 1924, brought his experiences with transsphenoidal surgery to Edinburgh, Scotland, and along the way, developed the lighted nasal speculum to provide better illumination in the narrow working area. Guiot, inspired by Dott, adopted his technique and used intraoperative radiofluoroscopic technique for image guidance. Hardy, a fellow of Guiot, from Montreal, Canada, revolutionized transsphenoidal microsurgery with the introduction of the binocular microscope and selective adenomectomy.

The teachings of these pioneers have endured over time and are now widely used by neurosurgeons worldwide. In this paper, we review the lineage and contributions of Dott, Guiot, and Hardy who served as crucial players in the preservation of transsphenoidal surgery.

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James K. Liu, Lana D. Christiano, Smruti K. Patel, and Jean Anderson Eloy

Retrochiasmatic craniopharyngiomas are challenging tumors to remove given their deep location and proximity to critical neurovascular structures. Complete surgical removal offers the best chance of cure and prevention of recurrence. The endoscopic endonasal extended transsphenoidal approach offers direct midline access to the retrochiasmatic space through a transplanum transtuberculum corridor. Excellent visualization of the undersurface of the optic chiasm and hypothalamus can be obtained to facilitate bimanual extracapsular dissection to permit complete removal of these formidable tumors. In this report the authors review the endoscopic endonasal extended transsphenoidal approach, with specific emphasis on technical operative nuances in removing retrochiasmatic craniopharyngiomas. An illustrative intraoperative video demonstrating the technique is also presented.

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James K. Liu, Lana D. Christiano, Smruti K. Patel, R. Shane Tubbs, and Jean Anderson Eloy

Olfactory groove meningiomas represent 10% of intracranial meningiomas and arise in the midline of the anterior cranial fossa along the dura of the cribriform plate and planum sphenoidale. Hyperostosis of the adjacent underlying bone is common, and further extension into ethmoid sinuses and nasal cavity can occur in 15%–25% of cases. Radical tumor resection including the involved dural attachment and underlying hyperostotic bone offers the best chance of a Simpson Grade I resection to minimize recurrence. Incomplete removal of involved hyperostotic bone can result in tumor recurrence at the cribriform plate with extension into the paranasal sinuses. Resection has traditionally been performed using a bifrontal or pterional approach, both of which require some degree of brain retraction or manipulation to expose the tumor.

The endoscopic endonasal transcribriform approach offers the most direct and immediate exposure to the tumor without brain retraction and manipulation of neurovascular structures. An endonasal “keyhole craniectomy” is performed in the ventral skull base directly over the basal dural attachment, extending from the posterior wall of the frontal sinus to the planum sphenoidale and tuberculum sellae in the anteroposterior plane, and from one medial orbit to the other in the coronal plane. Excellent panoramic visualization of the keyhole skull base defect can be obtained with a 30° endoscope after performing a modified Lothrop procedure. Because the dural attachment is adjacent to the paranasal sinuses, early devascularization and total Simpson Grade I removal of the tumor including the dural attachment and underlying hyperostotic bone can be achieved in properly selected patients. This approach is also very suitable for meningiomas that have recurred or extended into the paranasal sinuses. Extracapsular, extraarachnoid dissection of the tumor from the frontal lobes and neurovascular structures can be performed using conventional bimanual microsurgical techniques.

In this report, we review the surgical technique and describe our operative nuances for removal of olfactory groove meningiomas, including recurrent tumors with extension into the nasal cavity, using a purely endoscopic endonasal transcribriform approach. In addition, we discuss the advantages, limitations, patient selection, and complications of this approach. We specifically highlight our technique for multilayer reconstruction of large anterior skull base dural defects using fascia lata and acellular dermal allograft supplemented by bilateral vascularized pedicled nasoseptal flaps. Three new cases of endoscopically resected olfactory groove meningiomas are also presented.

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James K. Liu, Lana D. Christiano, Smruti K. Patel, R. Shane Tubbs, and Jean Anderson Eloy

Tuberculum sellae meningiomas frequently extend into the optic canals. Radical tumor resection including the involved dural attachment, underlying hyperostotic bone, and intracanalicular tumor in the optic canal offers the best chance of a Simpson Grade I resection to minimize recurrence. Decompression of the optic canal with removal of the intracanalicular tumor also improves visual outcome since this portion of the tumor is usually the cause of asymmetrical visual loss.

The purely endoscopic endonasal extended transsphenoidal approach offers a direct midline trajectory and immediate access to tuberculum sellae meningiomas without brain retraction and manipulation of neurovascular structures. Although the endoscopic approach has been previously criticized for its inability to remove tumor within the optic canals, complete Simpson Grade I tumor removal including intracanalicular tumor, dural attachment, and involved hyperostotic bone can be achieved in properly selected patients. Excellent visualization of the suprasellar region and the inferomedial aspects of both optic canals allows for extracapsular, extraarachnoid dissection of the tumor from the critical structures using bimanual microsurgical dissection.

In this report, the authors describe the operative nuances for removal of tuberculum sellae meningiomas with optic canal involvement using a purely endoscopic endonasal extended transsphenoidal (transplanum transtuberculum) approach. They specifically highlight the technique for endonasal bilateral optic nerve decompression and removal of intracanalicular tumor to improve postoperative visual function, as demonstrated in 2 illustrative cases. Special attention is also given to cranial base reconstruction to prevent CSF leakage using the vascularized pedicled nasoseptal flap.

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Smruti K. Patel, Yair M. Gozal, Mohamed S. Saleh, Justin L. Gibson, Michael Karsy, and George T. Mandybur

OBJECTIVE

Spinal cord stimulation has been shown to improve pain relief and reduce narcotic analgesic use in cases of complex refractory pain syndromes. However, a subset of patients ultimately undergoes removal of the spinal cord stimulator (SCS) system, presumably because of surgical complications or poor efficacy. This retrospective study addresses the paucity of evidence regarding risk factors and underlying causes of spinal cord stimulation failures that necessitate this explantation.

METHODS

In this retrospective single-center review, 129 patients underwent explantation of SCS hardware during a 9-year period (2005–2013) following initial placement at the authors’ institution or elsewhere. Medical history, including indication of implantation, device characteristics, revision history, and reported reasons for removal of hardware, were reviewed.

RESULTS

The 74 (57%) women and 55 (43%) men were a median of 49 years old (IQR 41–61 years) at explantation; the median time to explantation was 20 months (IQR 7.5–45.5 months). Thoracic or upper lumbar leads were placed in 89.9% of patients primarily for the diagnosis of postsurgical failed–back surgery syndrome (70.5%), chronic regional pain syndrome (14.7%), and neuropathic pain (8.5%). More than half of patients were legally disabled. Initial postoperative reduction in pain was reported in 81% of patients, and 37.8% returned to work. Among 15 patients with acute postsurgical complications (12 infections, 2 hemorrhages, 1 immediate paraplegia), the median time to removal was 2 months. Primary reasons for hardware removal were lack of stimulation efficacy (81%), electrode failure due to migration (14%), and allergic reactions to implanted hardware in 2 patients. The 72 patients who underwent formal psychiatric evaluation before implantation were affected by high rates of major depression (64%), anxiety (34%), posttraumatic stress disorder (PTSD) (12%), drug or alcohol abuse (12%), and physical or sexual abuse (22%).

CONCLUSIONS

The authors’ findings provide insight regarding the mechanisms of spinal cord stimulation failure that resulted in total removal of the implanted system. The relationship between spinal cord stimulation failure and certain psychiatric disorders, such as PTSD, depression, and anxiety, is highlighted. Ultimately, this work may shed light on potential avenues to reduce morbidity and improve patient outcomes.