Degeneration of an injured spinothalamic tract in a patient with mild traumatic brain injury

Partial isolated tear of the popliteus tendon following an in-car traffic accident: A rare cause of knee pain: A CARE-compliant case report

RATIONALE

Lesions caused by traffic accidents are often microscopic and minimal; therefore, their diagnosis can be easily overlooked. Moreover, when it is a rarely reported type of lesion, it can be even more easily undiagnosed. Isolated popliteal injuries are uncommon and have rarely been reported.

PATIENT CONCERNS

In this case study, we describe a right partially isolated popliteus tendon rupture that was undiagnosed for 2 years in a patient with posterior knee pain after an in-car traffic accident. A 49-year-old female patient presented with right knee pain that had persisted for 2 years and was initiated after an in-car traffic accident. The patient's right knee pain aggravated while standing and walking. Six months after the accident, her pain was confined to the posterolateral aspect of the knee and subsequently spread throughout her right knee. The pain score was 4 on a numerical rating scale. Physical examination revealed tenderness in the posterolateral corner of the right knee. Additionally, right knee pain was reported in the terminal range of knee flexion during the passive range of motion test. Radiographs of the right knee showed normal findings.

DIAGNOSES

A T2-weighted proton density sagittal and coronal knee magnetic resonance imaging revealed a partial-thickness tear with intrasubstance ganglion cysts at the musculotendinous junction of the popliteus tendon. No other abnormalities were observed in the patient.

INTERVENTION

Conservative treatment involved strengthening exercises and functional rehabilitation programs.

OUTCOMES

Six months later, the knee pain almost completely subsided.

LESSONS

Musculoskeletal injuries caused by traffic accidents are frequently overlooked. Therefore, a detailed examination should be conducted for an accurate diagnosis. Clinicians should consider the possibility of popliteal tendon injuries in patients with posterior knee pain.

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.

Diagnostic sensitivity of traumatic axonal injury of the spinothalamic tract in patients with mild traumatic brain injury

Diffusion tensor tractography (DTT) can detect traumatic axonal injury (TAI) in patients whose conventional brain magnetic resonance imaging results are negative. This study investigated the diagnostic sensitivity of TAI of the spinothalamic tract (STT) in patients with a mild traumatic brain injury (TBI) suffering from central pain symptoms, using DTT.Thirty-five patients with central pain following mild TBI and 30 healthy control subjects were recruited for this study. After DTT-based reconstruction of the STT, we analyzed the STT in terms of configuration (narrowing and/or tearing) and the DTT parameters (fractional anisotropy and tract volume).Thirty-three (94.3%) patients had at least 1 DTT parameter value at 1 standard deviation below the control group value, and 20 (57.1%) patients had values at 2 standard deviations, below the control group value. All 35 patients showed STT abnormalities (tearing, narrowing, or both) on DTT.A high diagnostic sensitivity of TAI of the STT in patients with mild TBI was achieved. However, the small number of subjects who visited the university hospital and the limitations of DTT should be considered when generalizing the results of this study.

The Usefulness of Diffusion Tensor Tractography in Diagnosing Neuropathic Pain: A Narrative Review

Diffusion tensor tractography (DTT) is derived from diffusion tensor imaging. It has allowed visualization and estimation of neural tract injury, which may be associated with the pathogenesis of neuropathic pain (NP). The aim of the present study was to review DTT studies that demonstrated the relationship between neural injuries and NP and to describe the potential use of DTT in the evaluation of neural injuries that are involved in the pathophysiological process of NP. A PubMed search was conducted for articles published until July 3, 2020, which used DTT to investigate the association between neural injuries and NP. The key search phrase for identifying potentially relevant articles was (diffusion tensor tractography AND pain). The following inclusion criteria were applied for article selection: (1) studies involving patients with NP and (2) studies in which DTT was applied for the evaluation of NP. Review articles were excluded. Altogether, 108 potentially relevant articles were identified. After reading the titles and abstracts and assessment of eligibility based on the full-text articles, 46 publications were finally included in our review. The results of the included studies suggested that DTT may be beneficial in identifying the pathophysiological mechanism of NP of various origins including central pain caused by brain injuries, trigeminal neuralgia, sciatica, and some types of headache. Further studies are needed to validate the efficacy of DTT in investigating the pathophysiology of other types of NP.

Abdominal pain due to the spinothalamic tract injury in patients with mild traumatic brain injury: a case report

Background

We report on a patient with a mild traumatic brain injury (TBI) who developed abdominal pain due to spinothalamic tract (STT) injuries revealed by diffusion tensor tractography (DTT).

Case presentation

A 53-year-old female patient suffered head trauma resulting from a backward fall. While bathing at a public bathhouse, she fell backward and struck the occipital area of her head against the floor. After the head trauma, she experienced pain in the abdomen and in both hands and feet. She underwent evaluations including conventional brain MRI, abdominal and pelvic ultrasonography, and stomach and intestine endoscopy. No abnormality was observed in her brain or abdomen. In addition, her abdominal pain had not been relieved by medical management. When she came to our hospital 4 years after the head trauma, her pain characteristics and severity were as follows: intermittent pain without allodynia or hyperalgesia; squeezing and warm creeping-like pain in the abdomen (visual analog scale score: 7); tingling pain in both hands and feet (visual analog scale score: 7). She was prescribed pregabalin and gabapentin, and her abdominal and limb pain was well-controlled at a tolerable level. On DTT 4 years after head trauma, the upper portion of the spinothalamic tracts (STTs) in both hemispheres showed partial tearing.

Discussion and conclusions

Injury of the STT was demonstrated by using DTT in a patient who showed abdominal pain that was refractory to medical management following mild TBI. Our results suggest that central pain due to STT injury might be suspected in patients with abdominal pain that is refractory to medical management following TBI.

Myelin Damage in Diffuse Axonal Injury

Diffuse axonal injury (DAI) is characterized by delayed axonal disconnection. Although the effect of DAI on axonal pathology has been well documented, there is limited information regarding the role of myelin in the pathogenesis of DAI. We used a modified Marmarou method to create a moderate DAI model in adult rat and examined the corpus callosum and brain stem for myelin pathology and dynamic glial responses to DAI. During the first week following DAI, Luxol Fast Blue staining and western blot analysis for MBP showed significant loss of myelin in the corpus callosum and the brain stem. Increased apoptosis of mature oligodendrocyte, as depicted by its marker CC-1, was observed. Conversely, there was an increased number of Olig2-positive cells accompanied by hypertrophic microglia/macrophage and mild reactive astrocytes. Electron microscopy revealed degenerating axons in the corpus callosum and marked myelin abnormalities in the brain stem in the early stage of DAI. Brain stem regions exhibited myelin intrusions or external protrusions with widespread delamination and myelin collapse, leading to degeneration of accompanying axons. Our results show distinct pathologic processes involving axon and myelin between the corpus callosum and the brain stem in DAI. Oligodendrocyte selective vulnerability and subsequent demyelination may contribute to axonal degeneration in the brain stem. Defining the cause of ongoing oligodendrocyte death and promoting myelin regeneration may provide important targets for therapeutic interventions of DAI.

Injury of auditory radiation and sensorineural hearing loss from mild traumatic brain injury

OBJECTIVES

We report on a patient with sensorineural hearing loss from injury of the auditory radiation following mild TBI, diagnosed by diffusion tensor tractography (DTT).

METHOD

A 35-year-old female patient suffered head trauma. While walking in a crosswalk, her left lumbar area was hit by a turning car and she fell to the ground. She was pulled behind the car for several meters while her occipital area repeatedly hit the ground. She complained that she began to feel hearing impairment approximately two weeks after the head trauma, that aggravated over time. Approximately 1.5 years after head trauma, when she visited a university hospital for evaluation of the brain, she complained of severe hearing impairment. To characterize the patient's hearing loss, pure tone audiometry was evaluated in a sound proof room to screen her hearing status for the frequencies 250-8000 Hz. A pure tone threshold in the range of 41-60 dB HL was considered moderate sensorineural hearing loss and 61-80 dB HL severe. However, no abnormality was observed in either ear on physical examination. The patient was diagnosed with bilateral moderate sensorineural hearing loss.

RESULTS

On 1.5 year DTT, the auditory radiation was narrowed in both hemispheres.

CONCLUSION

Neural injury of the auditory radiation was demonstrated in a patient with sensorineural hearing loss following mild TBI, using DTT.

Delayed-Onset Central Pain due to Degeneration of Ischemic Transcallosal Fibers After Corpus Callosum Hemorrhage

AIMS

A patient developed delayed-onset central pain due to degeneration of the spinothalamic tract resulting from degeneration of the ischemic transcallosal fibers, in the aftermath of a corpus callosum (CC) hemorrhage. The detection and diagnosis of these lesions using diffusion tensor tractography are described.

METHODS

A 59-yr-old man underwent conservative management for hemorrhages in the CC and lateral ventricle that resulted from hitting his head against a wall while falling. He began to feel pain in his right upper and lower extremities approximately 1½ yrs after the initial injury. The pain was characterized as constant tingling, numb, and cool sensation without allodynia or hyperalgesia (visual analogue scale score, 5).

RESULTS

Disruption of transcallosal fibers in the genu and isthmus of the CC was observed on diffusion tensor tractography 1 mo after the initial injury. By 3 yrs, the diffusion tensor tractography showed that transcallosal fibers in the isthmus (67.8%-77.9%) of the CC had disappeared, and the left spinothalamic tract had become thinner.

CONCLUSION

The results suggest that central pain can occur without direct injury of the spinothalamic tract and point up the need for evaluation of the spinothalamic tract and transcallosal fibers in patients with a CC lesion who complain of central pain.

Central post-stroke pain due to injury of the spinothalamic tract in patients with cerebral infarction: a diffusion tensor tractography imaging study

Many studies using diffusion tensor tractography (DTT) have demonstrated that injury of the spinothalamic tract (STT) is the pathogenetic mechanism of central post-stroke pain (CPSP) in intracerebral hemorrhage; however, there is no DTT study reporting the pathogenetic mechanism of CPSP in cerebral infarction. In this study, we investigated injury of the STT in patients with CPSP following cerebral infarction, using DTT. Five patients with CPSP following cerebral infarction and eight age- and sex-matched healthy control subjects were recruited for this study. STT was examined using DTT. Among DTT parameters of the affected STT, fractional anisotropy and tract volume were decreased by more than two standard deviations in two patients (patients 1 and 2) and three patients (patients 3, 4, and 5), respectively, compared with those of the control subjects, while mean diffusivity value was increased by more than two standard deviations in one patient (patient 2). Regarding DTT configuration, all affected STTs passed through adjacent part of the infarct and three STTs showed narrowing. These findings suggest that injury of the STT might be a pathogenetic etiology of CPSP in patients with cerebral infarction.

Relation between injury of the periaqueductal gray and central pain in patients with mild traumatic brain injury: Observational study

The periaqueductal gray (PAG) plays a pivotal role in pain modulation. We attempted to examine the relation between injury of the PAG and central pain in patients with mild traumatic brain injury (TBI).Sixty-one patients with mild TBI with central pain and 31 healthy control subjects were recruited for this study. Visual analog scale (VAS) was used for evaluation of central pain. The region of interest was defined for the PAG and the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured.The FA value was significantly lower in the patient group than in the control group (P < 0.05). However, no significant difference in the ADC value was observed between the patient and control groups (P > 0.05). VAS score of the patient group showed significant moderate negative correlation with the FA (r = -0.38), while no significant correlation was observed between VAS score and the ADC value (P < 0.05).We demonstrated injury of the PAG in patients with central pain following mild TBI and the degree of injury of the PAG was closely related to the degree of central pain.