Posterior fossa arachnoid cyst masking a delayed diagnosis of hyperparathyroidism in a child.

Background. Primary hyperparathyroidism in childhood is a very rare entity, often being diagnosed late after the onset of its presenting symptoms. It most commonly affects patients in their fourth decade of life and beyond. The inclusion of primary hyperparathyroidism in the differential diagnosis is necessary when evaluating patients presenting with nonspecific symptoms such as polyuria, fatigue, weight loss, abdominal pain, nausea, and vomiting. Methods. We report the case of an eleven-year-old girl presenting with three years history of headaches, visual disturbance, along with episodes of emotional lability. Neuroimaging confirmed a large posterior fossa arachnoid cyst. It was decided to manage this lesion conservatively with surveillance. Only after further hospital admissions with recurrent loss of consciousness, dizziness, and nausea to add to her already existing symptoms, a full biochemical and endocrine assessment was performed to look for more specific causes for her presentation. These pointed to a diagnosis of primary hyperparathyroidism. Conclusions. The inclusion of primary hyperparathyroidism in the differential diagnosis should be considered when evaluating paediatric patients presenting with nonspecific (neurological, gastrointestinal, and renal) symptoms in order to establish a prompt diagnosis of the disorder and to avoid severe complications of prolonged hypercalcaemia and end-organ damage.

Infantile clivus chordoma without clivus involvement: case report and review of the literature.

BACKGROUND: We present a giant clival chordoma with disseminated disease but without involvement of the clivus. To our knowledge, this is the youngest child and only the second case, presenting without base of skull involvement, in paediatric literature and the fourth reported case of a chordoma in a patient with tuberous sclerosis. DISCUSSION: We discuss the subtle presentation, difficulties in diagnosis and management and also review the literature.

Peroperative determination of safe superior transarticular screw trajectory through the lateral mass.

STUDY DESIGN: Computerized anatomic reconstruction of the dry axis vertebra was performed to determine radiologic guidelines for safe superior transarticular screw trajectory. OBJECTIVES: To reconstruct the transarticular screw trajectory, using computer-aided design techniques, and develop a technique that provides real-time intraoperative guidance during screw placement. SUMMARY OF BACKGROUND DATA: A recent osteometric study of 50 dry specimens of the axis noted significant vertebral artery groove anomalies in 22% of specimens. There are presently no anatomic or radiologic guidelines to help surgeons avoid an enlarged vertebral groove, despite the fact that a safe screw trajectory through the lateral mass is primarily dependent on the its depth and the internal height of the lateral mass. METHODS: Using computer-aided design techniques, we re-analyzed the vertebral grooves of 50 dry specimens and mapped minimum and corrected safe superior trajectories for any given depth of this groove. This knowledge was extrapolated to spiral computed tomographic scan data, which was used to develop the clinical method for safe superior trajectory. Real-time fluoroscopy was used to apply the method intraoperatively. RESULTS: Internal height less than 2.1 mm or values less than 0.85 for the ratio of the mean internal height over the mean vertebral groove depth would result in unacceptable risk to vertebral artery injury and improper screw purchase. With every 0.5-mm increase in groove depth, the angle of trajectory increases by 1 degree at a pedicle length of 30 mm. There is an inverse linear relation between the superior angle of trajectory and the pedicle length (2 degrees = 5 +/- 0.5 mm). Screw diameter-dependent trajectory correction is required (3.5 mm = 7 degrees). CONCLUSIONS: Before atlantoaxial transarticular surgery, vertebral groove depth should be evaluated and a safe screw trajectory angle should be plotted to determine anatomic suitability. This trajectory angle can be used with intraoperative real-time fluoroscopy to guide the surgeon during screw insertion.

Radiological and anatomical evaluation of the atlantoaxial transarticular screw fixation technique.

Sixty-one patients treated with C1-2 transarticular screw fixation for spinal instability participated in a detailed clinical and radiological study to determine outcome and clarify potential hazards. The most common condition was rheumatoid arthritis (37 patients) followed by traumatic instability (15 patients). Twenty-one of these patients (one-third) underwent either surgical revision for a previously failed posterior fusion technique or a combined anteroposterior procedure. Eleven patients underwent transoral odontoidectomy and excision of the arch of C-1 prior to posterior surgery. No patient died, but there were five vertebral artery (VA) injuries and one temporary cranial nerve palsy. Screw malposition (14% of placements) was comparable to another large series reported by Grob, et al. There were five broken screws, and all were associated with incorrect placement. Anatomical measurements were made on 25 axis bones. In 20% the VA groove on one side was large enough to reduce the width of the C-2 pedicle, thus preventing the safe passage of a 3.5-mm diameter screw. In addition to the obvious dangers in patients with damaged or deficient atlantoaxial lateral mass, the following risk factors were identified in this series: 1) incomplete reduction prior to screw placement, accounting for two-thirds of screw complications and all five VA injuries; 2) previous transoral surgery with removal of the anterior tubercle or the arch of the atlas, thus obliterating an important fluoroscopic landmark; and 3) failure to appreciate the size of the VA in the axis pedicle and lateral mass. A low trajectory with screw placement below the atlas tubercle was found in patients with VA laceration. The technique that was associated with an 87% fusion rate requires detailed computerized tomography scanning prior to surgery, very careful attention to local anatomy, and nearly complete atlantoaxial reduction during surgery.