Comorbid Neurodegeneration in Primary Progressive Aphasia: Clinicopathological Correlations in a Single-Center Study

Table 3

Imaging correlates of dorsal and ventral stream impairment. Midsagittal area of segments from the corpus callosum, according to two widely used segmentation schemes W: Witelson [29]; H: Hofer and Frahm [30]. Values are in square millimeters as measured on the midsagittal plane. Probabilistic tractography: the waytotal values of superior longitudinal fascicle (SLF) and inferior longitudinal fascicle (ILF) as reported by FSL. SFL and ILF ppm: parts per million, the ratio of the waytotal of the tract to bilateral tracts in the areas related to ventral and dorsal stream multiplied by 10⁶. See the Methods section for the list of ventral and dorsal stream areas.

Case	PPA subtype	Midsagittal area of callosal segments				Probabilistic tractography results
		W2	H3	H4	H5	SLF	SLF ppm	ILF	ILF ppm	SLF/ILF ratio
1	nfvPPA	51.4	47.9	27.5	123.2	N/A	N/A	N/A	N/A	N/A
2	nfvPPA	80.8	72.7	37.2	164.3	N/A	N/A	N/A	N/A	N/A
3	nfvPPA	35.8	46.5	23.1	140.2	737	1.82	5865	14.48	0.126
4	nfvPPA	74.6	76.1	35.3	143.1	6707	20.87	3382	10.52	1.983
5	nfvPPA	67.2	77.0	37.0	164.5	23756	51.36	19106	41.31	1.243
6	progr. dysarthria, late nfvPPA	43.6	37.7	18.8	95.5	N/A	N/A	N/A	N/A	N/A
7	Mixed nfvPPA+svPPA	40.1	42.2	23.1	107.5	N/A	N/A	N/A	N/A	N/A
8	svPPA	63.9	62.0	29.1	110.9	38	0.10	10167	28.72	0.003
9	lvPPA	81.5	79.2	41.0	127.3	25379	82.80	29328	95.69	0.865