Population demographics:
We retrospectively identified a total of 1058 mini-MDT records from this 30-month period, with 25 excluded due to incomplete or duplicated data. Of the 1033 records included, the mean age was 51.3 ± 18.3 years with females representing 65% of patients.
Over 99% of patients underwent an MRI brain, with 4 subjects requiring a CT brain due to severe claustrophobia, contraindications (e.g. permanent pacemaker) or patient preference.
As expected, many proformas had multiple 2WW referral criteria selected. Headache and symptoms raising suspicion of raised intracranial pressure represented the most frequent concern (headaches of recent onset n=662, posture related headache n=333, vomiting n=138, pulsatile tinnitus n=58 and papilloedema=10).
Prevalence of WMHs and cSVD:
Overall, 451 (43.7%) scans demonstrated evidence of WMHs with 60% of these scans deemed in keeping with cSVD (see Table 3). The prevalence of WMHs increased with age, from approximately 20% of patients under 50 years old to almost 90% of those over 80 years (see Figure 1a). Advancing age also appeared to correlate with increasing radiological burden of WMHs (see Figure 1b).
Table 3: Population demographics and prevalence of WMH by age group and radiological aetiology
|
Overall
|
Males
|
Females
|
WMHs by age group
|
<50 (%)
|
82 / 472 (17.4)
|
24 / 142 (16.9)
|
58 / 330 (17.6)
|
50 – 59 (%)
|
95 / 185 (51.4)
|
36 / 71 (50.7)
|
59 / 114 (51.8)
|
60 – 69 (%)
|
123 / 186 (66.1)
|
46 / 69 (66.7)
|
77 / 117 (65.8)
|
70 – 79 (%)
|
99 / 132 (75.0)
|
35 / 55 (63.7)
|
64 / 77 (83.1)
|
>80 (%)
|
52 / 58 (89.7)
|
23 / 25 (92.0)
|
29 / 33 (87.9)
|
WMHs by aetiology
|
Non specific (%)
|
174 (38.6)
|
63 (38.4)
|
111 (38.7)
|
Demyelinating (%)
|
9 (2.0)
|
4 (2.4)
|
5 (1.7)
|
Vascular (%)
|
268 (59.4)
|
97 (59.1)
|
171 (59.6)
|
WMHs by age group and aetiology
|
|
Non specific
|
Vascular
|
Demyelinating
|
<50 (%)
|
71 / 82 (86.6)
|
6 / 82 (7.3)
|
5 / 82 (6.1)
|
50 – 59 (%)
|
56 / 95 (59.0)
|
37 / 95 (38.9)
|
2 / 95 (2.1)
|
60 – 69 (%)
|
36 / 123 (29.3)
|
85 / 123 (69.1)
|
2 / 123 (1.6)
|
70 – 79 (%)
|
10 / 99 (10.1)
|
89 / 99 (89.9)
|
0 / 99 (0)
|
>80 (%)
|
1 / 52 (1.9)
|
51 / 52 (98.1)
|
0 / 52 (0)
|
Age also appeared to influence the radiological aetiology of WMHs (see Figure 2). Under the age of 50, WMHs were considered non-specific in 86% of scans where they were present, compared to <30% in those over 50. Indeed after age 50, the majority of WMHs were attributed to cSVD, rising to >90% of cases in patients over 70 years old.
There was no significant difference in the presence of overall WMHs (p=0.47) or cSVD (p=0.70) between males and females.
The proportion of patients with cSVD appeared higher in participants with WHO performance score >=1 (see Figure 3), indicating a degree of restricted activities. This was confirmed by Chi-squared test (p<0.001).
Risk factors for cSVD:
We performed logistic regression modelling to investigate which patient demographic factors impacted the likelihood of identifying cSVD. We found a significant relationship between age and presence of cSVD with a 14.5% increase in the odds ratio with each increased year of age (p<0.001). When we performed a sensitivity analysis whereby 10% of the radiological cSVD diagnoses were randomly inverted, age remained significant (p<0.001). Higher EST decile (indicative of higher levels of deprivation in terms of education, skills and training) was also associated with an increased risk of cSVD (p<0.05). Conversely, higher IMD decile was associated with a reduced risk of cSVD (p<0.05). HDD decile was non-significant (p=0.36). Patient sex (p=0.07) and WHO performance score (p=0.55) also did not reach statistical significance. Considering the magnitude of impact age had upon cSVD, we repeated a second model to only account for this factor. Whilst age remained a significant factor (p<0.001), AIC increased indicating that the additional demographic factors improved model fitting.
We also performed logistic regression modelling to identify whether any of the referral criteria were associated with cSVD. This revealed ‘headaches of recent onset’ (p<0.001) and ‘drowsiness’ (p<0.05) were associated with reduced cSVD prevalence. This was somewhat unexpected, as sleep disorders are well documented in cSVD.(30) Upon further inspection, it appeared these criteria were more common in younger patients and performing a conditional regression analysis adjusting for age reduced the significance of these findings.
Whilst the structured referral proforma does include designated fields for the recording of vascular risk factors and previous stroke, these were inconsistently documented and therefore excluded from our analysis.
Additional imaging findings:
In addition to WMHs, radiological abnormalities were identified on 438 (42.4%) scans (see Table 4). These were most commonly either ear, nose and throat abnormalities (e.g. sinus thickening), soft radiological signs of raised intracranial pressure (e.g. partially empty sella turcica, optic nerve tortuosity, enlarged optic nerve sheath or flattening of the optic nerve head) or vascular abnormalities (e.g. aneurysm, arteriovenous malformations or venous anomalies). Approximately 3% of scans demonstrated neoplastic disease (2.5% primary / 0.5% secondary brain tumours). Forty-five (4.4%) scans revealed >1 radiological abnormality.
Table 4: Additional radiological findings on routine 2WW brain imaging (soft signs of raised intracranial pressure suggestive of conditions such as idiopathic intracranial hypertension include a partially empty sella turcica, optic nerve tortuosity, enlarged optic nerve sheath and flattening of the optic nerve head)
Additional findings:
|
N (% of 1033 scans)
|
Recent infarct or haemorrhage
|
7 (0.7)
|
Neoplasm:
|
|
Primary brain tumour
|
26 (2.5)
|
- Of which are meningioma
|
18 (1.7)
|
Metastatic brain tumour
|
5 (0.5)
|
Cerebellar descent / tonsillar ectopia / Chiari malformation
|
38 (3.7)
|
ENT abnormality (e.g. sinus thickening)
|
81 (7.8)
|
Developmental brain anomaly
|
9 (0.9)
|
Pituitary signal change / suspected adenoma
|
19 (1.8)
|
Soft radiological signs of raised intracranial pressure
|
89 (8.6)
|
Microhaemorrhages or suggestive of cerebral amyloid angiopathy
|
11 (1.1)
|
Radiological signs of normal pressure hydrocephalus
|
7 (0.7)
|
Non-specific gliosis
|
44 (4.3)
|
Arachnoid cyst
|
11 (1.1)
|
Pineal cyst
|
18 (1.7)
|
Aneurysm / venous anomaly / AVM
|
46 (4.5)
|
Bone lesion
|
13 (1.3)
|