Transient mutism following posterior fossa surgery studied by single photon emission computed tomography (SPECT)

Abstract

Cerebellar mutism is a transient and not uncommon complication, following surgical resection of a tumor located in the posterior fossa. Children who develop this kind of mutism are conscious with good comprehension and no evidence of oral apraxia. It was described, for the first time, in children with cancer by Rekate et al. in 1985 [1].We have found a total of 87 cases in the English literature since 1985 [2-10], along with reports on two adults who were affected with cerebellar neoplasia [11,12].In our clinic, two of the medulloblastoma patients developed postoperative cerebellar mutism. The first was a 14-year-old girl; the second, an 8-year-old boy, was of particular interest because single photon emission tomography (SPECT) analysis in his case detected focal anatomic changes.He presented with headache and vomiting, visual disturbances, and nystagmus of 4 months' duration and magnetic resonance imaging (MRI) showed a tumor in the cerebellar vermis (floor of the fourth ventricle), extending down to the level of the first cervical vertebra. Obstructive hydrocephalus was also present.The neurosurgeon considered total resection impossible and two courses of preoperative chemotherapy (carboplatin 1,000 mg/m 2 etoposide 300 mg/m 2 , 21-28 days apart) were then administered. MRI performed 2 weeks after the second course showed tumor shrinkage of more than 50% and complete removal was then possible. Histology revealed a medulloblastoma. Four hours after surgery, the child spoke fluently, but 48 hr later developed mutism, and behavioral disturbances: refusal to eat, reaction of anger against the mother, decreased initiation of voluntary movements, and urinary incontinence with no obvious urologic or neurologic disorder. SPECT images revealed hypoperfusion in the left frontal and occipital zone and the right occipito-parietal zone (Figs. 1A and 2A,C).Neuro-psychological testing during the recovery period demonstrated poor initiation and completion of age appropriate motor and problem solving activities, despite improvement in overall mood.After a period of 90 days, the boy started to speak using single words, his speech rate was very slow, the words were spelled sound by sound with a strainedstrangled voice. The improvement was confirmed by SPECT images performed 6 months after the first. They revealed normal perfusion in the left frontal and right parieto-occipital regions and a reduction in the hypoperfusion in the left occipital region (Figs. 1B and 2B,D).Today, 20 months after neurosurgery, the child has not yet completely recovered fluent speech, and ataxia still persists. DISCUSSIONReversible alterations in regional cerebral blood flow (rCBF) can easily be detected by technetium-99m ethyl-cysteinate dimer (ECD) SPECT. Tc-ECD is a relatively small tracer (< 500 D), lipophylic, with a net charge of zero. It is able to cross the blood-brain barrier and is well distributed in the brain, but the radionuclide rapidly leaves the brain tissue. Ethyl-cysteinate dimer is a ligand that combines the features of high brain u...

Proximal dentatothalamocortical tract involvement in posterior fossa syndrome

“…To explain how a remote cerebellar injury may affect cortical functioning, a cerebello-cerebral diaschisis model has been proposed (Marien et al, 1996(Marien et al, , 2001Riva and Giorgi, 2000). Using diffusion tensor imaging, our findings further support this model and are not dissimilar from other studies that have utilized SPECT in patients with PFS (Sagiuchi et al, 2001;Clerico et al, 2002;Ersahin et al, 2002). These latter studies, as well as our current data, may suggest critical cortical regions involved in additional aspects of PFS such as apraxia and behavioural lability.…”

Posterior fossa syndrome in children following tumor resection: Knowledge update

“…[ 7 34 ] The syndrome is characterized most prominently by the absence or reduction in speech within 1–2 days of surgery without alteration in the level of consciousness. [ 6 12 28 ] Patients may retain the ability to produce speech immediately following surgery and become mute within an average of 2 days, but up to 7 days postoperatively. [ 12 29 ] Mutism is frequently accompanied by profound axial hypotonia and ataxia.…”

The Entity of Cerebellar Mutism Syndrome: A Narrative Review Centered on the Etiology, Diagnostics, Prevention, and Therapeutic Options

“…Mutism itself is inherently related to supratentorial dysfunction, mediated by crossed cerebello-cerebral diaschisis. This refers to a condition which is characterized by to an asymmetry of blood flow or metabolism in supratentorial structures contralateral to a remote cerebellar lesion [48,49]. Injury of the dentato-thalamocortical pathway is suggested to be the offending pathology of the crossed cerebello-cerebral diaschisis [49,50].…”