We describe a case of a large, petrous meningioma associated with tonsillar herniation and cervical syringomyelia. The patient, a 53-year-old woman, had a 6-month history of a dull, aching pain in the occipital region associated with numbness in the right C2 dermatome and left gaze evoked nystagmus. Magnetic resonance imaging (MRI) revealed a large tumor in the right posterior fossa associated with moderate supratentorial hydrocephalus. Secondary tonsillar herniation and cervical syringomyelia extending from C2 to C6 were also identified. The tumor, later confirmed to be a meningioma originating from the petrous region, was resected completely via a retrosigmoid approach. Postoperative MRI demonstrated total resolution of the tonsillar herniation and cervical syringomyelia. The radiological features, potential pathophysiological mechanisms, and treatment strategies are discussed in relation to the recent literature. In this interesting case report, a patient with a large posterior fossa meningioma presented with a Chiari I malformation and cervical syringomyelia. The Chiari malformation and syrinx resolved after the tumor was removed and a decompressive craniectomy, C1-C2 laminectomy, and duraplasty were performed. As the authors noted, this triad is rare, despite the incidence of posterior fossa meningiomas. Consequently, this patient's posterior fossa may already have been small. The authors treated both pathologies within the same surgical setting. Not surprisingly, these abnormalities resolved completely. Mr. Fox and colleagues present a well-written and well-illustrated case report along with a thorough review of the literature highlighting the potential for tumor-associated hindbrain herniation to lead to secondary spinal cord syrinx formation. While a rare association, it is one that should be recognized by skull base surgeons, particularly to avoid the mistake of initiating direct treatments for the syrinx, which almost always resolves over time once the hindbrain herniation has been reduced and normal flow of cerebrospinal fluid (CSF) and pressure equilibration dynamics have been restored. Indeed, we are increasingly recognizing that spinal cord syrinxes are almost always secondary phenomena. They usually improve or resolve after successful treatment of their primary cause. This holds true for lysing spinal canal arachnoid adhesions for post-traumatic or postmeningitic syrinxes; releasing caudal cord tension for tethered cord syrinxes (e.g., thickened filum, lipomeningocele, or scarred myelomeningocele repair); removing the spinal cord tumor for tumor-associated syrinxes; posterior fossa decompression of Chiari malformation-induced syrinx; anterior decompression for ventral compression or instability-induced syrinx (e.g., platybasia, C1-C2 rheumatoid arthritis); removing the shunt for lumboperitoneal shunt-induced syrinxes; and shunting the ventricles for hydrocephalus-induced hindbrain herniation leading to spinal cord syrinx. Removing a mass lesion (e.g., tumor) leading to hindbrain herniation should now be added to that list. Restoring normal flow of CSF and pressure equilibration dynamics throughout the craniospinal axis should be the goal. Primarily shunting or fenestrating a spinal cord syrinx should become a rare procedure, reserved for the small subset of cases where chronicity of the condition does not allow sufficient spontaneous resolution.

In exercising humans, cardiac output (CO) increases, with minor increases in pulmonary artery pressure (PAP). It is unknown if the CO is accommodated via distention of already perfused capillaries or via recruitment of nonconcomitantly perfused pulmonary capillaries. Ten subjects (9 female) performed symptom-limited exercise. Six had resting mean PAP (PAPm) <20 mmHg, and four had PAPm between 21 and 24 mmHg. The first-pass pulmonary circulatory metabolism of [³H]benzoyl-Phe-Ala-Pro (BPAP) was measured at rest and at peak exercise, and functional capillary surface area (FCSA) was calculated. Data are means ± SD. Mean pulmonary arterial pressure rose from 18.8 ± 3.3 SD mmHg to 28.5 ± 4.6 SD mmHg, CO from 6.4 ± 1.6 to 13.4 ± 2.9 L/min, and pulmonary artery wedge pressure from 14 ± 3.3 to 19.5 ± 5 mmHg (all P ≤ 0.001). Percent BPAP metabolism fell from 74.7 ± 0.1% to 67.1 ± 0.1%, and FCSA/body surface area (BSA) rose from 2,939 ± 640 to 5,018 ± 1,032 mL·min⁻¹·m⁻² (all P < 0.001). In nine subjects, the FCSA/BSA-to-CO relationship suggested principally capillary recruitment and not distention. In subject 10, a marathon runner, resting CO and FCSA/BSA were high, and increases with exercise suggested distention. Exercising humans demonstrate pulmonary capillary recruitment and distention. At moderate resting CO, increasing blood flow causes principally recruitment while, based on one subject, when exercise begins at high CO, further increases appear to cause distention. Our findings clarify an important physiologic question. The technique may provide a means for further understanding exercise physiology, its limitation in pulmonary hypertension, and responses to therapy.