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Mark Gregory Bigder and Anthony M. Kaufmann

OBJECT

Microvascular decompression (MVD) surgery for hemifacial spasm (HFS) is potentially curative. The findings at repeat MVD in patients with persistent or recurrent HFS were analyzed with the aim to identify factors that may improve surgical outcomes.

METHODS

Intraoperative findings were determined from review of dictated operative reports and operative diagrams for patients who underwent repeat MVD after prior surgery elsewhere. Clinical follow-up was obtained from the hospital and clinic records, as well as telephone questionnaires.

RESULTS

Among 845 patients who underwent MVD performed by the senior author, 12 had been referred after prior MVD for HFS performed elsewhere. Following repeat MVD, all patients improved and complete spasm resolution was described by 11 of 12 patients after a mean follow-up of 91 ± 55 months (range 28–193). Complications were limited to 1 patient with aggravation of preexisting hearing loss and mild facial weakness and 1 patient with aseptic meningitis without sequelae. Significant factors that may have contributed to the failure of the first surgery included retromastoid craniectomies that did not extend laterally to the sigmoid sinus or inferiorly to the posterior fossa floor in 11 of 12 patients and a prior surgical approach that focused on the cisternal portion of the facial nerve in 9 of 12 patients. In all cases, significant persistent neurovascular compression (NVC) was evident and alleviated more proximally on the facial root exit zone (fREZ).

CONCLUSIONS

Most HFS patients will achieve spasm relief with thorough alleviation of NVC of the fREZ, which extends from the pontomedullary sulcus root exit point to the Obersteiner-Redlich transition zone.

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Frederick A. Zeiler and Anthony M. Kaufmann

Repair of anterior skull base defects with vascularized grafts poses a significant challenge, given the location and small number of adequately sized vessels for free-flap anastomosis. This is particularly the case in the setting of redo surgery or in patients with preexisting soft-tissue trauma. Even more difficult is achieving a vascularized bone flap closure of such bony defects. The authors report a novel technique involving a rotational temporal bone flap with a temporalis muscle vascularized pedicle, which was used to repair an anterior fossa bony and soft-tissue defect created by recurrent malignancy.

A 55-year-old man with history of scalp avulsion during a motor vehicle accident, anterior fossa/nasopharyngeal malignant neuroendocrine carcinoma postresection, and bone flap infection presented with a recurrence of his skull base malignancy. The tumor was located in the anterior fossa, extending interhemispherically and down through the cribriform plate, ethmoid air cells, and extending into the nasopharyngeal cavity. Resection of the recurrent tumor was performed. The bony defect in the anterior skull base was repaired with a novel vascularized rotational temporal bone flap, with acceptable separation of the nasopharynx from the intracranial cavity.

The vascularized rotational temporal bone flap, in which a temporalis muscle pedicle is used, provides a novel and easily accessible means of vascularized bone closure of anterior skull base defects without the need for microsurgical free-flap grafting.

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Anthony M. Kaufmann and Angela V. Price

Peter Jannetta was a neurosurgery resident when he proposed the neurovascular compression theory. He built upon the astute observations of Dandy, Gardner, and others who, in the era before the operating microscope, had successfully ventured into the posterior fossa. In 1965, Jannetta performed cranial nerve microdissections for dental students and identified the trigeminal portio intermedia. He proposed that preservation of these sensory fibers may avoid complete facial numbness, and together with Robert Rand developed a subtemporal transtentorial approach for selective rhizotomy for trigeminal neuralgia (TN). Such rash surgery, using an operating microscope, was then forbidden at their University of California, Los Angeles center, so they collaborated with John Alksne to perform the first surgery at Harbor General Hospital. Upon visualizing the trigeminal nerve root, Jannetta was surprised to see a pulsating superior cerebellar artery compressing the nerve and said “That’s the cause of the tic.” He also hypothesized that alleviating the observed vascular cross-compression may be curative.

A few months later, while assessing a patient with hemifacial spasm, Jannetta had the epiphany that this was the same disease process as TN, but instead affecting the facial nerve. The patient consented to what would become Jannetta’s first microvascular decompression procedure. The senior faculty members who had forbidden such surgery were away, so the supervising neurosurgeon, Paul Crandall, granted the approval to perform the surgery and assisted. Via a retromastoid approach with the patient in the sitting position and using the operating microscope, Jannetta identified and alleviated the culprit neurovascular compression, with a cure resulting.

Jannetta presented his neurovascular compression theory and operative findings to the neurosurgical patriarchy of the time. Elders of the field were generally not inclined to accept the bold speculations of an untested neurosurgeon, and were often determined to discredit the new “cure” of the old diseases. Over decades of refining his surgical technique, documenting the outcomes, and enduring the skepticism he often faced, Jannetta’s theory and his microvascular decompression procedure withstood critical analysis and have become recognized as one the great discoveries and advances in neurosurgery and medicine.

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Marshall Wilkinson and Anthony M. Kaufmann

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Marshall F. Wilkinson, Tumul Chowdhury, W. Alan Mutch and Anthony M. Kaufmann

OBJECTIVE

Hemifacial spasm (HFS) is a cranial nerve hyperactivity disorder characterized by unique neurophysiological features, although the underlying pathophysiology remains disputed. In this study, the authors compared the effects of desflurane on facial motor evoked potentials (MEPs) from the spasm and nonspasm sides of patients who were undergoing microvascular decompression (MVD) surgery to test the hypothesis that HFS is associated with a central elevation of facial motor neuron excitability.

METHODS

Facial MEPs were elicited in 31 patients who were undergoing MVD for HFS and were administered total intravenous anesthesia (TIVA) with or without additional desflurane, an inhaled anesthetic known to centrally suppress MEPs. All measurements were completed before dural opening while a consistent mean arterial blood pressure was maintained and electroencephalography was performed. The activation threshold voltage and mean amplitudes of the MEPs from both sides of the face were compared.

RESULTS

There was a significantly lower mean activation threshold of facial MEPs on the spasm side than on the nonspasm side (mean ± SD 162.9 ± 10.1 vs 198.3 ± 10.1 V, respectively; p = 0.01). In addition, MEPs were also elicited more readily when single-pulse transcranial electrical stimulation was used on the spasm side (74% vs 31%, respectively; p = 0.03). Although desflurane (1 minimum alveolar concentration) suppressed facial MEPs on both sides, the suppressive effects of desflurane were less on the spasm side than on the nonspasm side (59% vs 79%, respectively; p = 0.03), and M waves recorded from the mentalis muscle remained unchanged, which indicates that desflurane did not affect the peripheral facial nerve or neuromuscular junction.

CONCLUSIONS

Centrally acting inhaled anesthetic agents can suppress facial MEPs and therefore might interfere with intraoperative monitoring. The elevated motor neuron excitability and differential effects of desflurane between the spasm and nonspasm sides support a mechanism of central pathophysiology in HFS.

Clinical trial registration no.: B2012:099 (clinicaltrials.gov)

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Andrew D. Firlik, Howard Yonas, Anthony M. Kaufmann, Lawrence R. Wechsler, Charles A. Jungreis, Melanie B. Fukui and Robert L. Williams

Object

The purpose of this study was to determine whether cerebral blood flow (CBF) measurements in acute stroke could be correlated with the subsequent development of cerebral edema and life-threatening brain herniation.

Methods

Twenty patients with aggressively managed acute middle cerebral artery (MCA) territory strokes who underwent xenon-enhanced computerized tomography (Xe-CT) CBF scanning within 6 hours of onset of symptoms were retrospectively reviewed. The relationship among CBF and follow-up CT evidence of edema and clinical evidence of brain herniation during the 36 to 96 hours following stroke onset was analyzed.

Initial CT scans displayed abnormal findings in 11 patients (55%), whereas the Xe-CT CBF scans showed abnormal findings in all patients (100%). The mean CBF in the symptomatic MCA territory was 10.4 ml/100 g/minute in patients who developed severe edema compared with 19 ml/100 g/minute in patients who developed mild edema (p < 0.05). The mean CBF in the symptomatic MCA territory was 8.6 ml/100 g/minute in patients who developed clinical brain herniation compared with 18 ml/100 g/minute in those who did not (p < 0.01). The mean CBF in the symptomatic MCA territory that was 15 ml/100 g/minute or lower was significantly associated with the development of severe edema and herniation (p < 0.05).

Conclusions

Within 6 hours of acute MCA territory stroke, Xe-CT CBF measurements can be used to predict the subsequent development of severe edema and progression to clinical life-threatening brain herniation. Early knowledge of the anatomical and clinical sequelae of stroke in the acute phase may aid in the triage of such patients and alert physicians to the potential need for more aggressive medical or neurosurgical intervention.

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Zachary J. Tempel, Srinivas Chivukula, Edward A. Monaco III, Greg Bowden, Hideyuki Kano, Ajay Niranjan, Edward F. Chang, Penny K. Sneed, Anthony M. Kaufmann, Jason Sheehan, David Mathieu and L. Dade Lunsford

OBJECT

Gamma Knife radiosurgery (GKRS) is the least invasive treatment option for medically refractory, intractable trigeminal neuralgia (TN) and is especially valuable for treating elderly, infirm patients or those on anticoagulation therapy. The authors reviewed pain outcomes and complications in TN patients who required 3 radiosurgical procedures for recurrent or persistent pain.

METHODS

A retrospective review of all patients who underwent 3 GKRS procedures for TN at 4 participating centers of the North American Gamma Knife Consortium from 1995 to 2012 was performed. The Barrow Neurological Institute (BNI) pain score was used to evaluate pain outcomes.

RESULTS

Seventeen patients were identified; 7 were male and 10 were female. The mean age at the time of last GKRS was 79.6 years (range 51.2–95.6 years). The TN was Type I in 16 patients and Type II in 1 patient. No patient suffered from multiple sclerosis. Eight patients (47.1%) reported initial complete pain relief (BNI Score I) following their third GKRS and 8 others (47.1%) experienced at least partial relief (BNI Scores II–IIIb). The average time to initial response was 2.9 months following the third GKRS. Although 3 patients (17.6%) developed new facial sensory dysfunction following primary GKRS and 2 patients (11.8%) experienced new or worsening sensory disturbance following the second GKRS, no patient sustained additional sensory disturbances after the third procedure. At a mean follow-up of 22.9 months following the third GKRS, 6 patients (35.3%) reported continued Score I complete pain relief, while 7 others (41.2%) reported pain improvement (BNI Scores II–IIIb). Four patients (23.5%) suffered recurrent TN following the third procedure at a mean interval of 19.1 months.

CONCLUSIONS

A third GKRS resulted in pain reduction with a low risk of additional complications in most patients with medically refractory and recurrent, intractable TN. In patients unsuitable for other microsurgical or percutaneous strategies, especially those receiving long-term oral anticoagulation or antiplatelet agents, GKRS repeated for a third time was a satisfactory, low risk option.