Aggravation of an injured dentato-rubro-thalamic tract in a patient with mild traumatic brain injury: A case report

Role of Diffusion Tensor Imaging in the Diagnosis of Traumatic Axonal Injury in Individual Patients with a Concussion or Mild Traumatic Brain Injury: A Mini-Review

Present review paper aims to understand role of diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) in diagnosis of traumatic axonal injury (TAI), induced by head trauma, in individual patients with a concussion or mild traumatic brain injury (mTBI). Precise information on presence and severity of TAI in brain is necessary for determining appropriate therapeutic strategies. Several hundred DTI-based studies have reported TAI in concussion or mTBI. Majority of these DTI-based studies have been performed in a group of patients, whereas case studies that have reported TAI in individual patients with a concussion or mTBI are fewer. Summary of these DTI-based studies for individual patients is as follows: DTI can be used as a non-invasive tool for determining presence and severity of TAI in individual patients with concussion or mTBI. However, for diagnosis of TAI in an individual patient, several conditions are required to be met: no past history of head trauma, presence of possible conditions for TAI occurrence during head trauma, development of new clinical features after head trauma, and DTI observed abnormality of a neural structure that coincides with a newly developed clinical feature. However, further studies for a more precise diagnosis of TAI in individual patients should be encouraged.

Injury of the dentato-rubro-thalamic tract in a patient with intentional tremor after mild traumatic brain injury: a case report

OBJECTIVES

We imaged the dentato-rubro-thalamic tract (DRTT) and cortico-ponto-cerebellar tract (CPCT) using diffusion tensor tractography (DTT) to evaluate the cortico-cerebellar-cortical circuit in a patient with tremor in both hands after mild TBI. We found bilateral DRTT injury in the DTT.

METHOD

A 50-year-old male presented with action tremor in both hands 1 week after mild TBI. One month before the visit, the patient had a head injury from a fall on a bus. The patient lost consciousness for 1 min and experienced post-traumatic amnesia for approximately 5 min after the accident. His Glasgow Coma Scale score was 15. The action tremor presented with a frequency of 3 Hz in both hands. No specific lesion was observed with a conventional brain MRI.

RESULTS

DTT, performed 1.5 months after TBI, showed that the right DRTT was not reconstructed and the left DRTT had thinned. However, CPCT integrity was well-preserved in both hemispheres. The tremor disappeared after oral treatment with 30 mg/day indenol. The patient's tremor would have been caused by disruption of the bilateral DRTT following mild TBI.

CONCLUSION

DRTT and CPCT analysis using DTT would be useful for diagnosing abnormal movement problems, including tremor and ataxia, in patients following mild TBI.

Injury of the dentatorubrothalamic tract in patients with post-traumatic tremor following mild traumatic brain injury: a case-control study

Post-traumatic movement disorder is one of the sequelae of traumatic brain injury. The dentatorubrothalamic tract (DRTT) is reported to be involved in the control of movement. Therefore, injury of the DRTT can be accompanied by abnormal movements, including ataxia, tremor, or dystonia. We investigated DRTT injuries in 27 patients who showed post-traumatic tremor in at least one of four extremities following mild traumatic brain injury. We classified DRTT injuries based on diffusion tensor tractography parameters and configuration: type A: the DRTT showed narrowing, type B: the DRTT showed partial tearing, and type C: the DRTT showed discontinuation. Fractional anisotropy and fiber number of the DRTT were significantly decreased in patients compared with the healthy controls. Based on our DRTT injury classification, among the 54 hemispheres of the 27 patients, type A injury occurred in 22 hemispheres (40.7%) of 17 patients, type B injury was present in 15 hemispheres (27.7%) of 10 patients, and type C injury was observed in 8 hemispheres (14.8%) of 6 patients. Our results suggest that diffusion tensor tractography-based evaluation of the DRTT would be useful when determining cause of post-traumatic tremor in patients with mild traumatic brain injury. The study protocol was approved by the Institutional Review Board of Yeungnam University Hospital (YUMC-2018-09-007) on September 5, 2018.

Comparison of posterior subthalamic area deep brain stimulation for tremor using conventional landmarks versus directly targeting the dentatorubrothalamic tract with tractography

OBJECTIVE

To compare posterior subthalamic area deep brain stimulation (PSA-DBS) performed in the conventional manner against diffusion tensor imaging and tractography (DTIT)-guided lead implantation into the dentatorubrothalamic tract (DRTT).

PATIENTS AND METHODS

Double-blind, randomised study involving 34 patients with either tremor-dominant Parkinson's disease or essential tremor. Patients were randomised to Group A (DBS leads inserted using conventional landmarks) or Group B (leads guided into the DRTT using DTIT). Tremor (Fahn-Tolosa-Marin) and quality-of-life (PDQ-39) scores were evaluated 0-, 6-, 12-, 36- and 60-months after surgery.

RESULTS

PSA-DBS resulted in marked tremor reduction in both groups. However, Group B patients had significantly better arm tremor control (especially control of intention tremor), increased mobility and activities of daily living, reduced social stigma and need for social support as well as lower stimulation amplitudes and pulse widths compared to Group A patients. The better outcomes were sustained for up to 60-months from surgery. The active contacts of Group B patients were consistently closer to the centre of the DRTT than in Group A. Speech problems were more common in Group A patients.

CONCLUSION

DTIT-guided lead placement results in better and more stable tremor control and fewer adverse effects compared to lead placement in the conventional manner. This is because DTIT-guidance allows closer and more consistent placement of leads to the centre of the DRTT than conventional methods.

Bidirectionality of the dentato-rubro-thalamo-cortical tract allows concurrent hypoperfusion in ipsilateral cerebellum and contralateral cerebral hemisphere: A case report

RATIONALE

The brain circulation of the dentato-rubro-thalamo-cortical tract (DRTT) has been reported for decade, but is rarely observed using nuclear medicine imaging tools, to analyze a patient with midbrain hemiatrophy syndrome. We present a case that revealed notable interruption in the middle of the DRTT. Finding out whether the superior cerebellar peduncle of the midbrain was injured was a decisive element for developing bidirectional effect of DRTT.

PATIENT CONCERNS

A 34-year-old right-handed female presented with progressive weakness and bradykinesia in the left-sided limbs for about 6 months. She had difficulty with hand dexterity for activities of daily life and general tasks. She reported poor balance during walking and sitting. Muscle strength was 3 in the left hand and 4 in the foot due to atrophy of left limbs. The circumference of 10 cm proximally/distally from the lateral epicondyle of the humerus was 25.7/23.8 cm at right and 24.2/20.8 cm at left in the upper limbs, and 15 cm proximally/distally from the lateral joint space was 42.1/35.0 cm at right and 43/30.8 cm at left in the lower limbs. The brain magnetic resonance imaging study revealed a small-sized right midbrain.

DIAGNOSIS

Based on the distinct features of limbs atrophy and the locations of the lesions on the magnetic resonance (MR) imaging, the patient was diagnosed with midbrain hemiatrophy syndrome.

INTERVENTIONS

The patient was only willing to accept physical and occupational training programs at our outpatient clinic.

OUTCOMES

We utilized serial anatomic and functional neuroimaging of the brain to survey the neurologic deficit. Brain perfusion single-photon emission computed tomography (SPECT) showed hypoperfusion over the left fronto-parietal regions, left anterior temporal region, and left occipital region, and also the left striatum and right cerebellum. Symptoms were gradually recovered with rehabilitation, and he was transferred to a rehabilitation facility on hospital day 40.

LESSONS

This is the first report to demonstrate concurrent hypoperfusion of ipsilateral cerebellum and contralateral cerebral hemisphere observed on SPECT images in a case of midbrain hemiatrophy syndrome. In our case, with midbrain hemiatrophy syndrome could be explained as mutual direction effect of DRTT.