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Nancy J. Fischbein, William P. Dillon, Charles Cobbs and Philip R. Weinstein

Object

Alteration of cerebrospinal fluid (CSF) flow has been proposed as an important mechanism leading to the development of syringomyelia. We hypothesize that a “presyrinx” condition due to potentially reversible alteration in normal CSF flow exists and that its appearance may be due to variations in the competence of the central canal of the spinal cord.

Methods

Five patients with clinical evidence of myelopathy, no history of spinal cord trauma, enlargement of the cervical spinal cord with T1 and T2 prolongation but no cavitation, evidence for altered or obstructed CSF flow, and no evidence of intramedullary tumor or a spinal vascular event underwent MR imaging before and after intervention that alleviated obstruction to CSF flow.

Results

Preoperatively, all patients demonstrated enlarged spinal cords and parenchymal T1 and T2 prolongation without cavitation. Results of magnetic resonance (MR) imaging examinations following intervention in all patients showed resolution of cord enlargement and normalization or improvement of cord signal abnormalities. In one patient with severe arachnoid adhesions who initially improved following decompression, late evolution into syringomyelia occurred in association with continued CSF obstruction.

Conclusion

Nontraumatic obstruction of the CSF pathways in the spine may result in spinal cord parenchymal T2 prolongation that is reversible following restoration of patency of CSF pathways. We refer to this MR appearance as the “presyrinx” state and stress the importance of timely intervention to limit progression to syringomyelia.

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Samuel F. Ciricillo, William P. Dillon, Matthew E. Fink and Michael S. B. Edwards

✓ The case of a young girl with a pericallosal venous malformation associated with multiple cryptic vascular malformations (CVM's) is described. The presenting cryptic malformation, which hemorrhaged, was completely excised, but the venous malformation was not. Routine follow-up magnetic resonance images obtained over the past 9 years have documented the development of multiple new cryptic malformations along the radicles of the venous malformation. Magnetic resonance imaging and cerebral angiography revealed venous outflow obstruction at the junction of the venous malformation with the straight sinus. The association of CVM's with anomalous venous drainage patterns and the role of venous hypertension in the pathogenesis of cryptic malformations are discussed. This case suggests that CVM's associated with a venous malformation may recur and new ones may develop if the venous malformation is not excised, particularly if venous hypertension is also present. The likelihood of a surgical cure in these patients may depend on complete excision of both anomalies, which is rarely feasible because of the potentially devastating results of resecting a venous malformation. Alternative treatments for patients with both types of lesions are discussed.

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Griffith R. Harsh, Charles B. Wilson, Grant B. Hieshima and William P. Dillon

✓ A patient with trigeminal neuralgia and hemifacial spasm was evaluated using multiplanar magnetic resonance (MR) imaging with gadolinium enhancement. Preoperative images demonstrated massively ectatic vertebral and basilar arteries and their distortion of the brain stem and the trigeminal and facial nerves. Surgical manipulation included selective trigeminal rhizotomy, cushioning of the residual nerve at the point of maximal distortion by the underlying basilar artery, and microvascular decompression of the seventh nerve from the anterior inferior cerebellar artery which was being pushed dorsomedially by the vertebral artery. Postoperatively, the patient had neither trigeminal neuralgia nor facial spasm. Gadolinium-enhanced MR imaging not only excludes other etiologies such as tumor or arteriovenous malformation, but also demonstrates cranial nerve compression by ectatic vertebral and basilar arteries. The choice of preoperative imaging modality is discussed and the literature concerning the etiology of tic convulsif is reviewed.

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Alfredo Quiñones-Hinojosa, Steven G. Ojemann, Nader Sanai, William P. Dillon and Mitchel S. Berger

Object. Broca identified the posterior third of the inferior frontal gyrus as a locus essential for the production of fluent speech. The authors have conducted this retrospective analysis in an attempt to find readily identifiable landmarks on magnetic resonance (MR) imaging that correspond to intraoperative cortical stimulation-induced speech arrest. These landmarks demonstrate novel structural—functional relationships that can be used preoperatively to predict the location of the Broca area.

Methods. Using a neuronavigation system, sites where stimulation produced speech arrest (Broca area) were recorded in a consecutive series of patients undergoing awake tumor resections in the perisylvian territory of the dominant hemisphere. The authors reviewed 33 consecutive patients by projecting the MR imaging data sets and marking the site where the Broca area was identified. Sulcus topography was analyzed with respect to this site by scrolling into neighboring planes and classifying the frontal operculum into one of the four schemes of sulcus variability described by Ebeling, et al. The following categories of frontal opercula were found: 18 (69%) of 26 were Type I, eight (31%) of 26 were Type III, and seven cases eluded classification because of sulcal effacement. For patients with Type I anatomy, the Broca area was adjacent to, and distributed evenly around, the inferior precentral sulcus (IPS). Quantitatively, the site of speech arrest was located a mean of 2.4 ± 0.25 cm from the anteroinferior aspect of the pars opercularis, where it abuts the subarachnoid space surrounding the apex of the pars triangularis. For all patients with Type III anatomy, the Broca area was adjacent to the accessory sulcus that lies immediately posterior to the IPS. In these patients the mean distance from the anterior inferior pars opercularis was 2.3 ± 0.29 cm. The mean distance from the Broca area to the edge of the tumor for the 26 patients with clear sulcal anatomy was 1.29 ± 0.12 cm.

Conclusions. The results indicate a correlation between the structure of the frontal operculum as seen on MR imaging and the functional localization of speech arrest in the dominant hemisphere. Additionally, sulcal landmarks that can be used preoperatively to predict the location of the Broca area within the inferior frontal gyrus are described based on the patient population. This information will allow the surgeon to determine if an awake craniotomy is necessary to identify the Broca area when planning a surgical procedure near the dominant frontal operculum.

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Devin K. Binder, Vahé Sarkissian, William P. Dillon and Philip R. Weinstein

✓ Spontaneous intracranial hypotension (SIH) is an increasingly recognized syndrome associated with a specific set of clinical and imaging findings; however, determining the site of spinal cerebrospinal fluid (CSF) leakage in these patients is often difficult, and indications for surgical intervention need to be better defined. The authors report on a 55-year-old woman who presented with posture-related headache, disorientation, and memory impairment. Imaging features were consistent with SIH. Computerized tomography myelography demonstrated a large T2–3 anterior transdural osteophyte associated with a CSF fistula. After an unsuccessful trial of conservative therapy, the patient underwent median sternotomy, T2–3 discectomy and removal of osteophyte, which allowed adequate exposure for primary dural repair. Postoperatively, there was immediate and prolonged resolution of all of her symptoms. This case of SIH was caused by transdural penetration by an anterior osteophyte and CSF leakage in the upper thoracic spine, which was treated effectively by anterior exposure and primary dural repair. Aggressive surgical intervention may be required to treat upper thoracic CSF leaks refractory to other measures.

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Arnold M. Meirowsky, William F. Caveness, James D. Dillon, Berkley L. Rish, Jay P. Mohr, J. Philip Kistler and George H. Weiss

✓ The records of 101 casualties of the war in Vietnam have been analyzed, with particular attention to missile wounds of the brain complicated by a cerebrospinal fluid (CSF) fistula. Fifty-four developed CSF drainage at the wound site, 30 presented with rhinorrhea, and 23 with otorrhea. Fifty of the 101 men developed infection, an incidence of 49.5%.

The occurrence of a fistula in vertex wounds can usually be traced to failure to close the dura, or to achieve watertight closure of the dura primarily, or by graft. Approximately two-thirds of compound basilar fractures, complicated by rhinorrhea or otorrhea, are due to direct fractures of the anterior, middle, or posterior fossa. The remaining one-third are due to elusive “discrete” fractures of the base of the skull, occurring at a distance from the entry wound, and not in continuity with the fracture of the vault. While direct basilar fractures can readily be recognized, facilitating repair of the dura overlying the basilar fractures, “discontinuous” fractures pose a challenging diagnostic problem. More commonly occurring in vertex wounds crossing the midline, discontinuous fractures producing rhinorrhea or otorrhea may be identified with the aid of tomograms of the base of the skull. Their early diagnosis may well prove to be a significant factor in the reduction of morbidity and mortality of missile wounds of the brain complicated by a CSF fistula.

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Berkley L. Rish, J. Daniel Dillon, William F. Caveness, Jay P. Mohr, J. Phillip Kistler and George H. Weiss

✓ A craniotomy debridement technique was recommended for penetrating craniocerebral injuries as early as 1940, in World War II. However, with due consideration for the bacterial contamination of penetrating injuries, the safety of this technique was questionable. The technique has been recommended in each succeeding war, but no data substantiating the safety or eventual sequelae have been available. Analysis of the data from the large Head Injury Registry of Vietnam casualties indicates that, in properly selected cases, debridement by craniotomy technique can be safe and efficacious.

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William F. Caveness, Arnold M. Meirowsky, Berkeley L. Rish, Jay P. Mohr, J. Philip Kistler, J. Daniel Dillon and George H. Weiss

✓ The development, recession, and residua of posttraumatic epilepsy follow natural laws that are imperfectly defined. However, studies from World War I, World War II, the Korean conflict, and the Vietnam War demonstrate the following patterns: 1) The onset of seizures is significantly related to local brain destruction and its location, and to diffuse brain damage, reflected by alteration in consciousness. 2) The incidence of seizures has remained the same from one war to another, in spite of marked improvement in patient transport, surgical techniques, medical management, and the prophylactic use of anticonvulsants in Vietnam. 3) After injuries incurred in combat and support activities, the onset of new cases of epilepsy rises sharply, with approximately 5% having a seizure in the first week, 10% in the first 3 months, 16% in the first 6 months, 23% in the first year, 29% in the first 2 years; after that there is a low, but protracted rate of new cases of epilepsy. 4) Those cases that occur in the first week are less influenced by the agent of injury or local brain damage, thereafter there is a sharp divergence with the more extensive injuries providing the greater number of patients with seizures. 5) In the population at risk, 65% to 75% never have a seizure. In those that do, the development varies in degree, adjudged from frequency of seizures. The latter ranges from a single seizure to a number that defies an accurate count. 6) As new patients with seizures accumulate, earlier patients cease having seizures. Within 5 to 10 years, one-half of the patients have ceased having seizures, with or without therapy. Half of the remainder, about 8% of the injured, have intractable seizures. 7) While there is a clear correlation between severity of injury and onset of seizures, there is no correlation between severity of injury and cessation of attacks. However, there is a correlation between the attack frequency and persistence of seizures. 8) From the preceding, two principal determinants are evident: the constitutional tendency toward seizures (probably a multifactorial genetic trait), and the brain damage. In onset of seizures, both play a part, the constitutional factor apparently determining severity of attacks. In cessation or persistence of seizures, the constitutional factor plays the dominant role.

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Alex Mamourian, Roger Bird, Pamela W. Schaefer, Scott W. Atlas, William P. Dillon, James M. Provenzale, Charles L. Truwit and Donald W. Chakeres