David M. Katz, Jonathan D. Trobe, Karin M. Muraszko, and Robert C. Dauser
✓ Four patients who developed increased intracranial pressure from ventricular shunt failure suffered a delay in diagnosis because magnetic resonance imaging of the brain did not show ventriculomegaly and because ophthalmic findings were initially overlooked or misinterpreted. None of the patients had the conventional manifestations of shunt failure: severe headache, nausea, vomiting, and depressed consciousness. Three patients suffered marked, permanent vision loss from chronic papilledema. These cases affirm that increased intracranial pressure may occur in shunt dependency without producing either conventional clinical symptoms or signs on imaging of the brain. Because ophthalmic manifestations may be the major clues to diagnosis, and because irreversible loss of vision is possible if these clues are overlooked, consideration should be given to periodic ophthalmological examination of shunt-dependent patients.
John M. Mesa, Frank Fang, Karin M. Muraszko, and Steven R. Buchman
Successful surgical repair of unicoronal plagiocephaly remains a challenge for craniofacial surgeons. Many of the surgical techniques directed at correcting the stigmata associated with this craniofacial deformity (for example, ipsilateral supraorbital rim elevation [vertical dystopia], ipsilateral temporal constriction, C-shaped deformity of the face, and so on) are not long lasting and often result in deficient correction and the need for secondary revision surgery. The authors posit that the cause of this relapse was intrinsic deficiencies of the current surgical techniques. The aim of this study was to determine if correction of unilateral coronal plagiocephaly with a novel hypercorrection surgical technique could prevent the relapse of the characteristics associated with unicoronal plagiocephaly.
The authors performed a retrospective analysis of 40 consecutive patients who underwent surgical repair of unicoronal plagiocephaly at their institution between 1999 and 2009. In all cases, the senior author (S.R.B.) used a hypercorrection technique for surgical reconstruction. Hypercorrection consisted of significant overcorrection of the affected ipsilateral frontal and anterior temporal areas in the sagittal and coronal planes. Demographic, perioperative, and follow-up data were collected for comparison. The postsurgical appearance of the forehead was documented clinically and photographically and then evaluated and scored by 2 independent graders using the expanded Whitaker scoring system. A relapse was defined as a recurrence of preoperative features that required secondary surgical correction.
The mean age of the patients at the time of the operation was 13 months (range 8–28 months). The mean follow-up duration was 57 months (range 3 months to 9.8 years). The postsurgical hypercorrection appearance persisted on average 6–8 months but gradually dissipated and normalized. No patients exhibited a relapse of unicoronal plagiocephalic characteristics that required surgical correction. In all cases the aesthetic results were excellent. Only 3 patients required reoperation for the management of persistent calvarial bone defects (2 cases) and removal of a symptomatic granuloma (1 case).
Our study demonstrates that patients who undergo unicoronal plagiocephaly repair with a hypercorrection surgical technique avoid long-term relapse. Our results suggest that the surgical technique used in the correction of unilateral coronal synostosis is strongly associated with the prevention of postsurgical relapse and that the use of this novel method decreases the need for surgical revision.
Mark R. Proctor, R. Michael Scott, W. Jerry Oakes, and Karin M. Muraszko
Implications for diagnosis and treatment
Edward H. Oldfield, Karin Muraszko, Thomas H. Shawker, and Nicholas J. Patronas
✓ The mechanisms previously proposed for the progression of syringomyelia associated with Chiari I malformation of the cerebellar tonsils are controversial, leave many clinical observations unexplained, and underlie the prevalence of different operations currently used as initial treatment. To explore the mechanism of syringomyelia progression in this setting, the authors used anatomical and dynamic (phase-contrast and phase-contrast cine) magnetic resonance (MR) imaging, and intraoperative ultrasonography to examine the anatomy and dynamics of movement of the cerebellar tonsils, the wall of the spinal cord surrounding the syrinx, and the movement of cerebrospinal fluid (CSF) and syrinx fluid at rest, during the respiratory and cardiac cycles, and during Valsalva maneuver in seven affected patients.
In all patients the cerebellar tonsils occluded the subarachnoid space at the level of the foramen magnum. Syringomyelia extended from the cervical to the lower thoracic segment of the spinal cord. No patient had evidence of a patent communication between the fourth ventricle and the syrinx on anatomical MR images, dynamic MR images, or intraoperative ultrasound studies. Dynamic MR images of three patients revealed abrupt downward movement of the spinal CSF and the syrinx fluid during systole and upward movement during diastole, but limited movement of CSF across the foramen magnum during the cardiac cycle. Intraoperative ultrasound studies demonstrated abrupt downward movement of the cerebellar tonsils during systole that was synchronous with sudden constriction of the spinal cord and syrinx. Decompression of the foramen magnum was achieved via suboccipital craniectomy, laminectomy of C-1 and C-2, and dural grafting, leaving the arachnoid intact. Immediately after surgery, the pulsatile downward thrust of the tonsils and constriction of the spinal cord and syrinx disappeared. Syringomyelia resolved within 1 to 6 months after surgery in all patients.
Observations by the authors suggest the following previously unrecognized mechanism for progression of syringomyelia associated with occlusion of the subarachnoid space at the foramen magnum. The brain expands as it fills with blood during systole, imparting a systolic pressure wave to the intracranial CSF that is accommodated in normal subjects by sudden movement of CSF from the basal cisterns to the upper portion of the spinal canal. With obstruction to rapid movement of CSF at the foramen magnum, the cerebellar tonsils, which plug the subarachnoid space posteriorly, move downward with each systolic pulse, acting as a piston on the partially isolated spinal CSF and producing a systolic pressure wave in the spinal CSF that acts on the surface of the spinal cord. This causes progression of syringomyelia by abruptly compressing the cord and propelling the fluid in the syrinx longitudinally with each pulse, and may be responsible for the origin and maintenance of syringomyelia by the pulsatile pressure waves forcing CSF into the cord through the perivascular and interstitial spaces. Effective treatment occurs when the systolic pressure wave transmitted by the cerebellar tonsils is eliminated by relieving the obstruction to rapid movement of subarachnoid CSF across the foramen magnum. The presence of this mechanism can be detected preoperatively on dynamic MR images and during surgery on ultrasound studies by the pulsatile excursion of the wall of the spinal cord surrounding the syrinx and by its immediate disappearance and the expansion of the syrinx during forced inspiration after decompression of the tonsils. Effective treatment is achieved with bone and dural decompression of the foramen magnum alone, without entering the arachnoid.
Tae Sung Park
Ryszard M. Pluta, Alois Zauner, Jay K. Morgan, Karin M. Muraszko, and Edward H. Oldfield
✓ Although proliferative arteriopathy has been postulated to play a role in the etiology of vasospasm after subarachnoid hemorrhage (SAH), histological and morphological studies examining cerebral vasospasm have produced conflicting results. To help settle this controversy, the authors used an in vivo label of cell division, bromodeoxycytidine, to assess cell proliferation in a primate model of SAH.
Fifteen cynomolgus monkeys received a clot of either whole blood (11 animals) or red blood cells (four animals) placed around the right middle cerebral artery (MCA). On the day of surgery continuous intravenous infusion of bromodeoxycytidine was begun and continued until the animal was sacrificed immediately after arteriography on Day 7, 12, or 27 following surgery. Sections from the right and left MCA's were stained with a monoclonal antibody against bromodeoxcytidine, and labeled cells were counted.
Arteriographic evidence of vasospasm occurred in nine monkeys on Day 7. On Day 12 and Day 27 no monkeys had persistent vasospasm. Placement of subarachnoid clot around the right MCA increased proliferative activity across all layers of the arterial wall. Most of the labeled cells were in the adventitia and the endothelium. Although there were more dividing cells in all layers of the right MCA than the left MCA (p < 0.01), the number of stained cells per section was limited (range 0.1 to 21.2, mean 8) and the occurrence of vasospasm was not associated with the number of dividing cells in the right MCA on Day 7, 12, 27, or for all days combined (p > 0.6).
Cerebral vasospasm after SAH was not associated with the extent of proliferation of cells in the vessel wall, nor could the intensity of the limited proliferative changes have been responsible for narrowing of the vessel diameter.
Tethered cord release
Joseph H. Piatt Jr.
Wajd N. Al-Holou, Karin M. Muraszko, Hugh J. Garton, Steven R. Buchman, and Cormac O. Maher
After primary repair of a myelomeningocele or a lipomyelomeningocele, patients can present with symptoms of secondary tethered cord syndrome (TCS). After surgical untethering, a small percentage of these patients can present with multiple repeat TCS. In patients presenting with secondary or multiple repeat TCS, the role as well the expected outcomes of surgical untethering are not well defined.
Eighty-four patients who underwent spinal cord untethering after at least 1 primary repair were retrospectively evaluated using scaled and subjective outcome measures at short-term and long-term follow-up visits. Outcomes were analyzed for predictive measures using multivariate logistic regression.
Surgical untethering was performed in 66 patients with myelomeningoceles and 18 patients with lipomyelomeningoceles. Fourteen patients underwent multiple repeat spinal cord untethering. Patients were followed up for an average of 6.2 years. Most patients had stability of function postoperatively. Motor function and weakness improved in 7 and 16% of patients at 6 months, respectively, and 6 and 19% of patients at long-term follow-up evaluation, respectively. Of the patients who presented with back pain, 75% had improvement in symptoms at 6 months postoperatively. Younger age at untethering was significantly associated with worse long-term neurological outcomes. The number of previous untethering procedures, original diagnosis, sex, anatomical level, and degree of untethering had no effect on surgical outcomes.
Patients presenting with secondary or multiple repeat TCS may benefit from surgical untethering.