Clinical Reasoning: An unusual lung mass causing focal weakness

Intraoperative visualization of cranial nerve schwannomas using second-window indocyanine green: A case series

BACKGROUND

Second Window Indocyanine Green (SWIG) is a novel intraoperative imaging technique that uses near-infrared (NIR) light for intra-operative tumor visualization using the well-known fluorophore indocyanine green (ICG). Because schwannomas often incorporate the nerve into the encapsulated tumor and impinge on surrounding neural structures, SWIG is a promising technique to improve tumor resection while sparing the nerve.

OBJECTIVE

To demonstrate the use of SWIG in resection of cranial nerve schwannomas.

METHODS

Three patients with cranial nerve schwannomas (i.e., trigeminal, vestibular, and vagus) underwent SWIG-guided resection. During surgery, NIR visualization was used intermittently used to detect fluorescence to guide resection. Signal-to-background ratio was then calculated to quantify fluorescence.

RESULTS

Patients were infused with ICG at a dose of 5.0 mg/kg 24 hours before surgery. Each patient achieved total or near-total resection and relief of symptoms with lack of recurrence at six-month follow-up. The average SBR calculated was 3.79, comparable to values for SWIG-guided resection of other brain and spine tumors.

CONCLUSION

This case series is the first published report of trigeminal and vagus nerve schwannoma resection using the SWIG technique and suggests that SWIG may be used to detect all schwannomas, alongside many other types of brain tumor. This paper also demonstrates the importance of preoperative ICG infusion timing and discusses the inverse pattern of NIR signal that may be observed when infusion occurs outside of the optimal timing. This provides direction for future studies investigating the administration of SWIG to resect cranial nerve schwannomas and other brain tumors.

Isolated schwannoma of the urinary bladder: a case report and review of the literature

The urinary bladder schwannoma is an extremely rare primary urologic tumor. Schwannoma arises from the Schwann's cells in the nerve sheaths and is almost associated with von Recklinghausen's disease. We report a case of schwannoma in a 35-year old female who presented with urinary frequency for 2 months with absence of evidence of von Recklinghausen disease and successfully treated with transurethral resection of bladder lesion (TUR_B). To the best of our knowledge, this represents only the 10^th case of benign schwannoma of the urinary bladder in a patient without von Recklinghausen disease. We report a case of an isolated schwannoma of the urinary bladder, and also searched the English literature as we had access to bladder schwannoma.

Management of extremity neurilemmomas: clinical series and literature review. Ann Plast Surg. 2013;71 Suppl 1:S37-S42. [PMID: 24284739 DOI: 10.1097/sap.0000000000000042]

BACKGROUND

Delicate enucleation of neurilemmoma preserves most of nerve fascicles and causes minimal nerve function impairment. Accurate preoperative diagnosis of neurilemmoma is based on clinical findings and image studies.

MATERIALS AND METHODS

Between November 2003 and February 2013, operations for the treatment of neurilemmoma were performed on 14 patients (12 men and 2 women) at our institution. The image studies in this series were collected. The tumor mass was approached by splitting the epineurium. In a few cases, enucleation of the neurilemmoma caused some fascicles loss, but reconstruction with sural nerve grafts preserved nerve function.

RESULTS

Before surgery, 7 patients received computed tomographic scan, 4 patients underwent magnetic resonance imaging, and 3 patients received sonography. Six patients presented with motor or sensory deficits immediately after tumor enucleation. Three patients recovered completely from the neurological defects with or without nerve reconstruction.

CONCLUSIONS

Our results indicate that neurilemmoma can be removed by delicate enucleation with an acceptable risk of injury to the nerve trunk.