Results, SPECT Brain Perfusion Findings in Mild / Moderate Traumatic Brain Injury

SPECT BRAIN PERFUSION FINDINGS IN MILD OR MODERATE TRAUMATIC BRAIN INJURY

RESULTS:

The patient population included 135 males, 93 females. the age ranged from 11- 88 years (mean 40.8). The etiology of brain trauma was a history of: MVA 103/228 (45%), blow to the head 82/228 (36%) and fall 43/228 (19%).

The most common complaints were characteristic of the post-concussion syndrome (PCS): headaches 139/228 (60.9%); dizziness 61/228 (26.7%); memory problems 63/228 (27.6%); sleep disorders 20/228 (8.7%), concentration problems 19/228 (8.3%); visual problems 18/228 (7.9%); balance problems 10/228 (4.4%); depression 6/228 (2.6%); and, hearing problems 5/228 (2.2%). Normal studies accounted for 52/228 (23%), Fig. 1 and abnormal studies (176/228) (77%). The total number of lesions (hypoperfusion) in 176 abnormal SPECT brain perfusion studies were 612 averaging 3.5 lesions per patient and were distributed as follows: basal ganglia and thalami (BG) 338 (55.2%) Fig 3; frontal lobes 146 (23.8%) Fig. 2; temporal lobes 80 (13%); parietal lobes 20 (3.7%); insular and/or occipital lobes together 28 lesions (4.6%). A pattern of diffuse supratentorial hypoperfusion was observed in a total of 35 patients (20%). The insular and occipital abnormalities were grouped together because of the small number of lesions. Of considerable interest and significance is the finding that BG abnormalities were more common than the previously recognized frontal lobes (p=0.006) and temporal lobes abnormalities (p= 0.0003).

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Association of the patients’ most common complaints and abnormal SPECT:

The association of presenting symptoms with abnormal SPECT was as follows: dizziness 51/61 (84%); headaches 103/139 (74%); and memory problems 46/63 (73%). Overall BG abnormalities were most common. The average number of lesions for given symptoms was as follows: headaches 188 lesions were detected in 103 abnormal SPECT studies (1.83 lesion/ abnormal study); dizziness: 95 lesions in 51 abnormal SPECT (1.86 lesion/ abnormal study); memory problems: 115 lesions for 46 abnormal SPECT (2.5 lesion / abnormal study ). For the main presenting symptoms of headache, dizziness, and memory problems, frontal lobe abnormalities were: 0.63, 0.73, and 0.78 lesion / abnormal study, respectively; temporal lobe abnormalities were: 0.46, 0.63, and 0.65 lesions/ abnormal study; respectively; parietal abnormalities: 0.15, 0.1 and 0.15 lesion/ abnormal study, respectively. Association of memory problems with BG abnormalities were significantly higher than in those with complaints of headache (p =0.0005), and in those patients complaining of dizziness (p=0.003) .

Differences Between Early and Delayed Imaging:

SPECT brain perfusion was done in 122/228 (53.5% ) of cases within 3 months from the date of the accident, and the rest 106/228 ( 46.5% ) had the study over 3 months from the date of the injury and less than 3 years. There were 382 lesions in 92 studies of patients who were imaged within 3 months from the date of trauma (average 4.2 lesions per study) and 230 lesions in 84 who were imaged after 3 months from the date of trauma (average 2.7 lesion per study). Diffuse supratentorial hypoperfusion was noticed in 12 (15%) in those patients imaged within 3 month versus 23 (24%) in those imaged more than 3 month. This might indicate that diffuse supratentorial hypoperfusion could be due to the facts that has been previously reported in the literature that brain injury following traumatic brain injury is a progressive process. There was a significant difference when patients were imaged earlier < 3 month from the time of the accident versus when imaged late > 3 month from the date of the injury. Early imaging identified more lesions than delayed imaging with a p=0.0011. Because the 2 groups compared are different, we realized that this is not the ideal way of evaluating early versus delayed imaging. It is possible that patients with late examination had different neuropathology or subjective complaints warranting study but not necessarily involving lesions manifested by hypoperfusion. Longitudinal follow up of the two groups is recommended, which is currently under limited investigation in our lab. However, because the large number of studies reviewed in our series makes the assumption based on our results plausible .

Association with Loss of Consciousness:

Loss of consciousness (LOC) status was reported to be positive in 121/228 (53%) and negative in 41/228 (18%) (status was not reported in the medical records for the remainder in 66 patients(29%). The results for patients with reports of no history of LOC are: 28/41 (68%) of the SPECT studies were read as abnormal and 13/41 (32%) was read as normal. Reports of focal hypoperfusion abnormalities were as follows: frontal lobes 13/28 (46%); basal ganglia 14/28 (50%);. temporal lobes 5/28 (18%); and, parietal 4/28 (14%). SPECT brain perfusion abnormalities can therefore occur in the absence of LOC. In this subset of patients' CT results were available in 32/41, all reported to be negative. This further confirms that SPECT brain perfusion is more sensitive in detecting lesions post mild traumatic brain injury. This subgroup of patients without LOC has been the subject of a separate publication ⁽³³⁾.

Intraobserver Agreement:

The intraobserver agreement was 92% for the frontal and temporal, 88% for the parietal , 78 % for the basal ganglia and 100% for the diffuse supratentorial hypo-perfusion.

Figure I is an example of a normal study. Figure II is an example of bilateral frontal and parietal hypo-perfusion and Figure III is an example of bilateral basal ganglia and thalamic hypo-perfusion.

Drawbacks of the Study:

One of our disappointments - although this was not the objective of this presentation - was our inability to compare the SPECT findings to CT findings. Data of CT findings were obtained from the referring physician, patient, or medical record in 162/228. All were either normal, or with no significant findings. Most were not available for us to review. The rest 66/228 it was unknown if the patient had a CT and if the patient did have one, the results were not known. We generally assume that patients who were referred for a SPECT brain perfusion study had no abnormalities on CT. We therefore have concluded that a comparison between the CT findings and SPECT brain perfusion would be unreliable in this report.

Another drawback is the findings were not correlated with Neuropsychologic analysis which were not available to us.