Neuropsychological Outcome of AVM Treatment

Abstract

Neurological sequalae of the treatment of brain AVMs has been extensively studied, where each patient could be appropriately informed about the possible surgical risk of AVM resection according to the Spetzler-Martin grading system. However, only few reports have systemically evaluated neuropsychological sequalae in a population of AVM patients. The main factors influencing neuropsychological outcome in patients with AVMs are:

• 1. Haemorrhagic presentation with possible focal neurological and cognitive domain deficit according to lesion location

• 2. Frequency of seizures and severity of epilepsy

• 3. Steal phenomenon

• 4. Type and duration of symptoms and initial level of consciousness

We evaluated the neuropsychological outcome of our patients treated for brain AVMs using standardised neuropsychological tests and then compared these results with those of a control group chosen from a local background population. Furthermore, we have compared neuropsychological functions across treatment modalities.

The final patient cohort included 39 males and 27 females with a mean age of 38 ± 16 years. Microsurgical resection was performed in 35 patients, endovascular embolisation in 17 and Leksell Gamma Knife (LGK)/conservative management (observation) in 14. Thirty-six malformations were localised in the dominant hemisphere. Thirty malformations were localised in the non-dominant hemisphere. Twenty-six malformations were in the frontal lobe, 19 in the temporal lobe and 15 in the parietal and occipital lobes. The remaining six AVM s were in deep structures. Thirty-two AVMs were Spetzler-Martin grades I&II, 18 were grade III and 16 were grades IV&V. Clinical presentation was haemorrhage in 31 cases (intracerebral haemorrhage in 25, intraventricular haemorrhage in 10 and subarachnoid haemorrhage in 17). Seizure was the presenting feature in 21 cases. Complete obliteration of AVMs was achieved in 41 patients: 33 patients with microsurgical resection, 5 with embolisation 2 after LGK and 1 after spontaneous obliteration.

A control group comprised ten presumably healthy subjects (age 44 ± 10 years) without any neurologic disease.

Neuropsychological testing was performed using a test battery constructed specifically for this study consisting of the following standard tests:

• Verbal/Language intelligence was tested by Vana’s intelligence test (VIT)

• Frontal/Execution functions were tested by the Czech version of the FAS test and the Trail making test, part B

• Attention and processing speed was measured by the Trail making test, part A

• Nonverbal intelligence was measured by the Test of intellectual potential (TIP)

• Visuospatial functions by Cubes analysis, a subtest of the visual object and space perception (VOSP) battery

• Verbal memory and fluency was measured by the Auditory-verbal learning test (AVLT) and Verbal fluency tests

Patients harbouring non-obliterated high-grade AVMs (S-M IV–V) scored worse than patients harbouring non-obliterated AVMs S-M grade I–III. This finding could be explained by the steal phenomenon. No differences in neuropsychological testing were found when the results were compared based on the nidus location. These facts lends support to an active treatment policy for cerebral AVMs. Those patients in whom treatment achieved complete obliteration scored similarly to the background population, suggesting that active AVM treatment doesn’t cause deterioration in neuropsychological performance. Furthermore, there was no difference between the various treatment modalities. More than 90% of the AVM obliteration rate favors microsurgery as the treatment of choice if the AVM could be safely resected.