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Jonathan A. Forbes

OBJECTIVE

Active-duty neurosurgical coverage has been provided at Bagram Air Force Base in Afghanistan since 2007. Early operative logs were reflective of a large number of surgical procedures performed to treat battlefield injuries. However, with maturation of the war effort, the number of operations for battlefield injuries has decreased with time. Consequently, procedures performed for elective neurosurgical humanitarian care (NHC) increased in number and complexity prior to closure of the Korean Hospital in 2015, which resulted in effective termination of NHC at Bagram. Monthly neurosurgical caseloads for deployed personnel have dropped precipitously since this time, renewing a debate as to whether the benefits of providing elective NHC in Afghanistan outweigh the costs of such a strategy. To date, there is a paucity of information in the literature discussing the overall context of such a determination.

METHODS

The author retrospectively reviewed his personal database of all patients who underwent neurosurgical procedures at Bagram during his deployment there from April 17 to October 29, 2014. Standardized clinical parameters had been recorded in the ABNS NeuroLog system. All cases of nonelective surgical care for battlefield injuries were identified and excluded. Records of all other procedures, which represented elective NHC delivered during this period, were accessed to extract salient clinical and radiological data.

RESULTS

During the 6-month deployment, 49 patients (29 male and 20 female, age range 18 months to 63 years) were treated by the author in elective NHC. Procedures were performed for spinal degenerative disease (n = 28), cranial tumors (n = 11), pediatric conditions (n = 6), Pott’s disease (n = 2), peripheral nerve impingement (n = 1), and adult hydrocephalus (n = 1). The duration of follow-up ranged from 3 to 23 weeks. Complications referable to surgery included asymptomatic, unilateral lumbar screw fracture detected 3 months postoperatively and treated with revision of hardware (n = 1); wound infection requiring cranial flap explantation and staged cranioplasty (n = 1); and unanticipated return to the operating room for resection of residual tumor in a patient with a solitary metastatic lesion involving the mesial temporal lobe/ambient cistern (n = 1). There were no instances of postoperative neurological decline.

CONCLUSIONS

Elective NHC can be safely and effectively implemented in the deployed setting. Benefits of a military strategy that supports humanitarian care include strengthening of the bond between the US/Afghan military communities and the local civilian population as well as maintenance of skills of the neurosurgical team during the sometimes-lengthy intervals between cases in which emergent neurosurgical care is provided for treatment of battlefield injuries.

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Jonathan A. Forbes, Ahmed J. Awad, Scott Zuckerman, Kevin Carr and Joseph S. Cheng

Object

The authors' goal was to better define the relationship between biomechanical parameters of a helmeted collision and the likelihood of concussion.

Methods

The English-language literature was reviewed in search of scholarly articles describing the rotational and translational accelerations observed during all monitored impact conditions that resulted in concussion at all levels of American football.

Results

High school players who suffer concussion experience an average of 93.9g of translational acceleration (TA) and 6505.2 rad/s2 of rotational acceleration (RA). College athletes experience an average of 118.4g of TA and 5311.6 rad/s2 of RA. While approximately 3% of collisions are associated with TAs greater than the mean TA associated with concussion, only about 0.02% of collisions actually result in a concussion. Associated variables that determine whether a player who experiences a severe collision also experiences a concussion remain hypothetical at present.

Conclusions

The ability to reliably predict the incidence of concussion based purely on biomechanical data remains elusive. This study provides novel, important information that helps to quantify the relative insignificance of biomechanical parameters in prediction of concussion risk. Further research will be necessary to better define other factors that predispose to concussion.

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Jonathan A. Forbes, Andrea A. Brock, Mayshan Ghiassi, Reid C. Thompson, David S. Haynes and Betty S. Tsai

Jugulotympanic paragangliomas were first described approximately 75 years ago. Since that time, there has been considerable evolution in knowledge of tumor biology, methods of classification, and appropriate management strategies. This paper attempts to summarize these gains in information.

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Scott L. Zuckerman, Andrew Kuhn, Michael C. Dewan, Peter J. Morone, Jonathan A. Forbes, Gary S. Solomon and Allen K. Sills

Object

Sports-related concussions (SRCs) represent a significant and growing public health concern. The vast majority of SRCs produce mild symptoms that resolve within 1–2 weeks and are not associated with imaging-documented changes. On occasion, however, structural brain injury occurs, and neurosurgical management and intervention is appropriate.

Methods

A literature review was performed to address the epidemiology of SRC with a targeted focus on structural brain injury in the last half decade. MEDLINE and PubMed databases were searched to identify all studies pertaining to structural head injury in sports-related head injuries.

Results

The literature review yielded a variety of case reports, several small series, and no prospective cohort studies.

Conclusions

The authors conclude that reliable incidence and prevalence data related to structural brain injuries in SRC cannot be offered at present. A prospective registry collecting incidence, management, and follow-up data after structural brain injuries in the setting of SRC would be of great benefit to the neurosurgical community.

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Adib A. Abla, Scott D. Wait, Jonathan A. Forbes, Sandipan Pati, Roger E. Johnsonbaugh, John F. Kerrigan and Yu-Tze Ng

Object

In this paper, the authors' goal was to describe the occurrence of alternating hypernatremia and hyponatremia in pediatric patients who underwent resection of hypothalamic hamartomas (HHs) for epilepsy. Hypernatremia in patients after pituitary or hypothalamic surgery can be caused by diabetes insipidus (DI), whereas hyponatremia can occur due to a syndrome of inappropriate antidiuretic hormone, cerebral salt wasting, or excessive administration of desmopressin (DDAVP). The triphasic response after surgery in the pituitary region can also explain variations in sodium parameters in such cases.

Methods

One hundred fifty-three patients with HH who underwent surgery were enrolled in a prospective study to monitor outcomes. Of these, 4 patients (2.6%) were noted to experience dramatic alterations in serum sodium values. The medical records of these patients were identified and evaluated.

Results

Patients' ages at surgery ranged from 1.2 to 6.0 years. All patients were girls. Two patients had Delalande Type IV lesions (of 16 total Type IV lesions surgically treated) and 2 had Type III lesions (of 39 total Type III lesions). All patients had a history of gelastic seizures refractory to medication. Seizure frequency ranged from 3 to 300 per day. After surgery, all patients experienced hypernatremia and hyponatremia. The largest fluctuation in serum sodium concentration during hospitalization in a single patient was 53 mEq/L (range 123–176 mEq/L). The mean absolute difference in maximum and minimum sodium values was 38.2 mEq/L.

All patients exhibited an initial period of immediate DI (independent of treatment) after surgery followed by a period of hyponatremia (independent of treatment), with a minimum value occurring between postoperative Days 5 and 8. All patients then returned to a hypernatremic state of DI, and 3 patients still require DDAVP for DI management. A second occurrence of hyponatremia lasting several days without DDAVP administration occurred in 2 patients during their hospitalization between periods of hypernatremia. One patient stabilized in the normal range of sodium values prior to discharge from rehabilitation without the need for further intervention. At last follow-up, 3 patients are seizure-free.

Conclusions

Severe instability of sodium homeostasis with hypernatremia and hyponatremia is seen in up to 2.6% of children undergoing open resection of HH. This risk appears to be related to HH type, with a higher risk for Types III (2 [5.1%] of 39) and IV (2 [12.5%] of 16) lesions. Here, the authors describe alternating episodes of hypernatremia and hyponatremia in the postoperative period following HH surgery. Management of this entity requires careful serial assessment of volume status and urine concentration and will often require alternating salt replacement therapy with DDAVP administration.

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Malte Ottenhausen, Kavelin Rumalla, Andrew F. Alalade, Prakash Nair, Emanuele La Corte, Iyan Younus, Jonathan A. Forbes, Atef Ben Nsir, Matei A. Banu, Apostolos John Tsiouris and Theodore H. Schwartz

OBJECTIVE

Anterior skull base meningiomas are benign lesions that cause neurological symptoms through mass effect on adjacent neurovascular structures. While traditional transcranial approaches have proven to be effective at removing these tumors, minimally invasive approaches that involve using an endoscope offer the possibility of reducing brain and nerve retraction, minimizing incision size, and speeding patient recovery; however, appropriate case selection and results in large series are lacking.

METHODS

The authors developed an algorithm for selecting a supraorbital keyhole minicraniotomy (SKM) for olfactory groove meningiomas or an expanded endoscopic endonasal approach (EEA) for tuberculum sella (TS) or planum sphenoidale (PS) meningiomas based on the presence or absence of olfaction and the anatomical extent of the tumor. Where neither approach is appropriate, a standard transcranial approach is utilized. The authors describe rates of gross-total resection (GTR), olfactory outcomes, and visual outcomes, as well as complications, for 7 subgroups of patients. Exceptions to the algorithm are also discussed.

RESULTS

The series of 57 patients harbored 57 anterior skull base meningiomas; the mean tumor volume was 14.7 ± 15.4 cm3 (range 2.2–66.1 cm3), and the mean follow-up duration was 42.2 ± 37.1 months (range 2–144 months). Of 19 patients with olfactory groove meningiomas, 10 had preserved olfaction and underwent SKM, and preservation of olfaction in was seen in 60%. Of 9 patients who presented without olfaction, 8 had cribriform plate invasion and underwent combined SKM and EEA (n = 3), bifrontal craniotomy (n = 3), or EEA (n = 2), and one patient without both olfaction and cribriform plate invasion underwent SKM. GTR was achieved in 94.7%. Of 38 TS/PS meningiomas, 36 of the lesions were treated according to the algorithm. Of these 36 meningiomas, 30 were treated by EEA and 6 by craniotomy. GTR was achieved in 97.2%, with no visual deterioration and one CSF leak that resolved by placement of a lumbar drain. Two patients with tumors that, based on the algorithm, were not amenable to an EEA underwent EEA nonetheless: one had GTR and the other had a residual tumor that was followed and removed via craniotomy 9 years later.

CONCLUSIONS

Utilizing a simple algorithm aimed at preserving olfaction and vision and based on maximizing use of minimally invasive approaches and selective use of transcranial approaches, the authors found that excellent outcomes can be achieved for anterior skull base meningiomas.