Mustafa Nadi and Rajiv Midha
Mustafa Nadi, Navid Khezri, Tahani Ahmad, Michael Ellis, Eric Bouffet, James T. Rutka and Michael D. Taylor
Medulloblastoma is a highly malignant brain tumor of childhood. Although craniospinal dissemination within the subarachnoid space is common, invasion of the dural sinuses is rare. Here, the authors report on a 15-year-old girl who presented with a right cerebellar mass, obstructive hydrocephalus, and radiographic evidence of tumor invasion into the right transverse–sigmoid sinus junction. The patient underwent posterior fossa craniotomy, gross-total resection of the intraparenchymal component of the right cerebellar tumor, and coagulation of the tumor invading the transverse sinus. After pathological confirmation of anaplastic medulloblastoma, the patient underwent craniospinal radiation therapy and high-dose chemotherapy. At 2 years posttreatment, the child was neurologically intact with no radiographic evidence of residual disease or recurrence. The implications for disease prognosis and management are discussed.
Mustafa Nadi, Sudheesh Ramachandran, Abir Islam, Joanne Forden, Gui Fang Guo and Rajiv Midha
Supercharge end-to-side (SETS) transfer, also referred to as reverse end-to-side transfer, distal to severe nerve compression neuropathy or in-continuity nerve injury is gaining clinical popularity despite questions about its effectiveness. Here, the authors examined SETS distal to experimental neuroma in-continuity (NIC) injuries for efficacy in enhancing neuronal regeneration and functional outcome, and, for the first time, they definitively evaluated the degree of contribution of the native and donor motor neuron pools.
This study was conducted in 2 phases. In phase I, rats (n = 35) were assigned to one of 5 groups for unilateral sciatic nerve surgeries: group 1, tibial NIC with distal peroneal-tibial SETS; group 2, tibial NIC without SETS; group 3, intact tibial and severed peroneal nerves; group 4, tibial transection with SETS; and group 5, severed tibial and peroneal nerves. Recovery was evaluated biweekly using electrophysiology and locomotion tasks. At the phase I end point, after retrograde labeling, the spinal cords were analyzed to assess the degree of neuronal regeneration. In phase II, 20 new animals underwent primary retrograde labeling of the tibial nerve, following which they were assigned to one of the following 3 groups: group 1, group 2, and group 4. Then, secondary retrograde labeling from the tibial nerve was performed at the study end point to quantify the native versus donor regenerated neuronal pool.
In phase I studies, a significantly increased neuronal regeneration in group 1 (SETS) compared with all other groups was observed, but with modest (nonsignificant) improvement in electrophysiological and behavioral outcomes. In phase II experiments, the authors discovered that secondary labeling in group 1 was predominantly contributed from the donor (peroneal) pool. Double-labeling counts were dramatically higher in group 2 than in group 1, suggestive of hampered regeneration from the native tibial motor neuron pool across the NIC segment in the presence of SETS.
SETS is indeed an effective strategy to enhance axonal regeneration, which is mainly contributed by the donor neuronal pool. Moreover, the presence of a distal SETS coaptation appears to negatively influence neuronal regeneration across the NIC segment. The clinical significance is that SETS should only employ synergistic donors, as the use of antagonistic donors can downgrade recovery.
Daipayan Guha, Benjamin Davidson, Mustafa Nadi, Naif M. Alotaibi, Michael G. Fehlings, Fred Gentili, Taufik A. Valiante, Charles H. Tator, Michael Tymianski, Abhijit Guha and Gelareh Zadeh
A surgical series of 201 benign and malignant peripheral nerve sheath tumors (PNSTs) was assessed to characterize the anatomical and clinical presentation of tumors and identify predictors of neurological outcome, recurrence, and extent of resection.
All surgically treated PNSTs from the Division of Neurosurgery at Toronto Western Hospital from 1993 to 2010 were reviewed retrospectively. Data were collected on patient demographics, clinical presentation, surgical technique, extent of resection, postoperative neurological outcomes, and recurrence.
One hundred seventy-five patients with 201 tumors had adequate follow-up for analysis. There were 182 benign and 19 malignant PNSTs. Of the benign lesions, 133 were schwannomas, 21 of which were associated with a diagnosis of schwannomatosis. There were 49 neurofibromas, and 26 were associated with neurofibromatosis Type 1 (NF1). Patients presenting with schwannomas were significantly older than those with neurofibromas. Schwannomas were more readily resected than neurofibromas, with the extent of resection of the former influenced by tumor location. Patients with benign PNSTs typically presented with a painful mass and less frequently with motor deficits. The likelihood of worsened postoperative motor function was decreased in patients with fully resected tumors or preoperative deficits. Recurrence of schwannomas and neurofibromas were seen more frequently in patients diagnosed with NF3 and NF1, respectively. Subtotal resection was associated with the increased recurrence of all benign lesions.
Outcomes following resection of benign PNSTs depend on tumor histopathology, tumor location, and genetic predisposition syndrome. Gross-total resection should be attempted for benign lesions where possible. The management of malignant PNSTs remains challenging, requiring a multimodal approach.