Posterior Fossa Syndrome
Introduction
The development of mutism after resection of large pediatric vermian tumors was first noted anecdotally by Hirsch et al. (1979) and Sakai et al. (1980) and has remained a source of confusion and consternation for neurosurgeons caring for such children. Studies in our institution (Pollack et al., 1995) and elsewhere (Aguiar et al., 1993; Ammirati et al., 1989; Boratynski and Wocjan, 1993, Catsman-Berrevoets et al., 1992; Cochrane et al., 1994; Dailey et al., 1995; D'Avanzo et al., 1993; Dietze and Mickle, 1990–1991; Ferrante et al., 1990; Gaskill and Marlin, 1991–1992; Herb and Thyen, 1992; Humphreys, 1989; Nagatani et al., 1991; Rekate et al., 1985; Salvati et al., 1991; Van Calenbergh et al., 1995; Van Dongen et al., 1994; Volcan et al., 1986; Wisoff and Epstein, 1984) indicate that the development of mutism in this setting is not rare, occurring in as many as 15% of children with vermian tumors. In addition to the speech impairment, affected patients often exhibit a spectrum of characteristic neurobehavioral deficits (Cochrane et al., 1994; Dailey et al., 1995; Gaskill and Marlin, 1991–1992; Humphreys, 1989; Pollack et al., 1995; Rekate et al., 1985; Von Dongen et al., 1994; Volcan et al., 1986; Wisoff and Epstein, 1984), which may include eating dysfunction, emotional lability, impaired eye opening, incontinence, and, in some instances, decreased initiation of a wide range of voluntary activities. Fortunately, in most cases, these deficits resolve completely during a period of several weeks to months.
Despite the frequency and dramatic nature of this syndrome, the anatomical substrate for the speech and neuropsychiatric dysfunction has remained uncertain. However, the recent availability of high-resolution imaging techniques and the growing recognition of the complex interconnections between the cerebellum and higher cortical centers provide the basis for rational insights into the structural etiology for this phenomenon and potential ways for minimizing the frequency of this syndrome. This chapter reviews our experience with the diagnosis and treatment of such patients in the context of the existing neurosurgical and neuroanatomic literature, presents a hypothesis regarding the anatomical substrates for this unusual syndrome, and discusses ways in which the frequency of this problem may be decreased.
Section snippets
General Features
One hundred and forty-two children underwent resection of an infratentorial tumor between 1985 and 1994 at the Children's Hospital of Pittsburgh; 92 had lesions that primarily involved the vermis. Twelve of the children (8.5%) exhibited postoperative mutism in the absence of any obvious cause, such as profound neurological impairment as a result of the tumor, the surgical procedure, or meningitis (Table I). As noted later in the chapter, the spectrum of the syndrome in terms of the duration of
Clinical Features of the Syndrome
During the last decade, more than 50 cases of mutism and/or bizarre personality changes have been reported after the removal of posterior fossa mass lesions. These are reviewed in detail in Pollack et al. (1995). As with our own cases, these patients have generally been young and have had large midline cerebellar and fourth ventricular tumors that were resected via an inferior vermian incision. However, two of our cases and one of Dietze and Mickle (1990) are distinctive in that a superior
Acknowledgment
This work was supported in part by a grant from the National Institutes of Health (KO8NS01810).
References (58)
- et al.
Cerebellar mutism in an adult: Case report
Surg. Neurol.
(1994) - et al.
Posterior fossa medulloblastoma in childhood: Treatment results and a proposal for a new staging system
Int. J. Radiat. Oncol. Biol. Phys.
(1990) - et al.
The cerebellum and learning processes in animals
Brain Res. Rev.
(1990) - et al.
The human cerebro-cerebellar system: Its computing, cognitive, and language skills
Behav. Brain Res.
(1991) - et al.
Cognitive and language function of the human cerebellum
Trends Neurosci.
(1993) - et al.
Mutism after removal of a vermian medulloblastoma: Cerebellar mutism
Surg Neurol.
(1991) - et al.
Motor imagery activates the cerebellum regionally: A SPECT rCBF study with 99mTc-HMPAO
Cogn. Brain Res.
(1993) - et al.
Transient cercbellar mutism after posterior fossa surgery in an adult: Case report and review of the literature
Clin. Neurol. Neurosurg.
(1991) - et al.
Itracranial ependymoma: Long-term results of a policy of surgery and radiotherapy
Int. J. Radial. Oncol. Biol. Phys.
(1992) - et al.
Speech deficits in ischaemic cerebellar lesions
J. Neurol
(1992)